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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]

Copyright of Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu is the property of Chinese Journal of Tissue Engineering Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

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]

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]

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]

Copyright of Chinese Journal of Refrigeration Technology is the property of Shanghai Society of Refrigeration and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Copyright of Journal of Anhui Agricultural Sciences is the property of Journal of Anhui Agricultural Sciences Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

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]

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]

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]

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]

Copyright of Shandong Medical Journal is the property of Shandong Medical Health Newspapers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Molecular oxygen is a primary oxidant that is involved in the formation of active oxygen species and in the oxidation of lipids and proteins. Thus, controlling oxygen partial pressure (concentration) in the human organism, tissues, and organs can be the first step in protecting them against oxidative stress. However, it is not an easy task because oxygen is necessary for ATP synthesis by mitochondria and in many biochemical reactions taking place in all cells in the human body. Moreover, the blood circulatory system delivers oxygen to all parts of the body. The eye lens seems to be the only organ that is protected from the oxidative stress through the regulation of oxygen partial pressure. The basic mechanism that developed during evolution to protect the eye lens against oxidative damage is based on the maintenance of a very low concentration of oxygen within the lens. This antioxidant mechanism is supported by the resistance of both the lipid components of the lens membrane and cytosolic proteins to oxidation. Any disturbance, continuous or acute, in the working of this mechanism increases the oxygen concentration, in effect causing cataract development. Here, we describe the biophysical basis of the mechanism and its correlation with lens transparency. [ABSTRACT FROM AUTHOR]

Gas tungsten arc welding (GTAW) is commonly used for joining pipelines; however, it often leads to discoloration in the heat-affected zone (HAZ). In this study, 316L pipes were welded with different concentrations of oxygen present in the argon purge gas during welding. The objective of this study was to investigate the effect of oxygen concentration in the protective gas on the pitting corrosion resistance of welded pipes. The experimental results showed that the thickness of the oxide layer formed in the HAZ depends on the concentration of oxygen in the protective gas. Increasing the oxygen concentration in the protective gas resulted in an increase in pitting corrosion resistance until a critical value, beyond which the resistance decreased. The results showed that the thickness of the oxide layer formed in the HAZ depends on the concentration of oxygen in the protective gas. Increasing the oxygen concentration in the protective gas increased the pitting corrosion resistance until a critical value, beyond which the resistance decreased due to the formation of iron oxide. This study provides valuable insights for improving the corrosion resistance of welded pipes in the oil and gas industry. [ABSTRACT FROM AUTHOR]

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 (P<0.01). Onehalf of the zygotes were cultured under normal temperature (38.5°C) during the culture period, and the other half of the zygotes were heat stressed at 41°C for six hours. Then they transferred into the normal culture conditions for the rest of the period using 0, 10-6, and 10-9 M of melatonin (Group IV). Under normal temperature (38.5°C), melatonin at 10-9 M was beneficial for in vitro development and DNA integrity. Under heat stress at 41°C, melatonin at 10-6 and 10-9 M was useful for in vitro development and DNA integrity (P<0.05). Supplementation of melatonin to embryo culture medium did not alter the caspase 3 and 7 activities (P>0.05). In conclusion, melatonin prevents the adverse effects of heat stress and O2 tension on preimplantation bovine embryos in vitro. [ABSTRACT FROM AUTHOR]

Smoldering is slow, low-temperature, and flameless burning of porous fuel, and it is also an emerging method for energy conversion and waste removal. However, smoldering combustion is an incomplete combustion process, so the pollutions resulted from smoldering emissions are significant concerns. This work explores the flaming of emission gases from the smoldering wood chips (200 kg/m3) under different oxidizer flow velocities (4 mm/s-24 mm/s) and oxygen concentrations (14%-21%) through porous media. Once ignited on the top, the smoldering front first propagates downward (1st stage, opposed) to the bottom and then propagates upward (2nd stage, forward). We found that during the 1st-stage downward smoldering propagation, a stable flame of smoldering emissions could be piloted and sustained. The critical smoldering burning rate for maintaining a stable flame remains constant at 10–12 g/m2∙s. To reach such a minimum smoldering burning rate, the required opposed flow velocity increases from 6 to 24 mm/s, as the oxygen concentration decreases from 21 to 14%. A simplified heat transfer process is proposed to reveal the limiting conditions for the co-existence of flaming and smoldering. This work enriches strategies for the clean treatment of smoldering emissions and promotes an energy-efficient and environment-friendly method for biowaste removal. [ABSTRACT FROM AUTHOR]

Capillary biofilm reactors (CBRs) are attractive for growing photoautotrophic bacteria as they allow high cell‐density cultivation. Here, we evaluated the CBR system's suitability to grow an artificial consortium composed of Synechocystis sp. PCC 6803 and Pseudomonas sp. VBL120. The impact of reactor material, flow rate, pH, O2, and medium composition on biomass development and long‐term biofilm stability at different reactor scales was studied. Silicone was superior over other materials like glass or PVC due to its excellent O2 permeability. High flow rates of 520 μL min−1 prevented biofilm sloughing in 1 m capillary reactors, leading to a 54% higher biomass dry weight combined with the lowest O2 concentration inside the reactor compared to standard operating conditions. Further increase in reactor length to 5 m revealed a limitation in trace elements. Increasing trace elements by a factor of five allowed for complete surface coverage with a biomass dry weight of 36.8 g m−2 and, thus, a successful CBR scale‐up by a factor of 25. Practical application: Cyanobacteria use light energy to upgrade CO2, thereby holding the potential for carbon‐neutral production processes. One of the persisting challenges is low cell density due to light limitations and O2 accumulation often occurring in established flat panel or tubular photobioreactors. Compared to planktonic cultures, much higher cell densities (factor 10 to 100) can be obtained in cyanobacterial biofilms. The capillary biofilm reactor (CBR) offers good growth conditions for cyanobacterial biofilms, but its applicability has been shown only on the laboratory scale. Here, a first scale‐up study based on sizing up was performed, testing the feasibility of this system for large‐scale applications. We demonstrate that by optimizing nutrient supply and flow conditions, the system could be enlarged by factor 25 by enhancing the length of the reactor. This reactor concept, combined with cyanobacterial biofilms and numbering up, holds the potential to be applied as a flexible, carbon‐neutral production platform for value‐added compounds. [ABSTRACT FROM AUTHOR]

Copyright of Journal of New Medicine is the property of Sun Yat Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Additive manufacturing processes are among the most innovative manufacturing processes of this century. Powder-based direct metal deposition (DMD) is one of these processes. In the DMD process, local shielding takes place via the powder nozzle. The process is therefore critical for oxidation, especially for materials with an affinity for oxidation such as titanium, aluminum and their alloys. In order to study the oxidation behavior in more detail, the present gas dynamics must be further understood. Wirth and Wegener have made a first approach with their gas flow simulation. In this study, a measurement method for spatial oxygen concentration determination is presented. It can be shown that the spatial oxygen concentration follows the nozzle geometry. Furthermore, the coaxial nozzle is superior to the three-jet nozzle with respect to a low oxygen concentration from a carrier gas to shielding gas volume flow ratio of equal to or greater than 0.4. Finally, it can be shown that the use of a shielding gas chamber eliminates the optimization of the gas flow settings. [ABSTRACT FROM AUTHOR]

The genetic disorder, ataxia‐telangiectasia (A‐T), is caused by loss of the homeostatic protein kinase, ATM, and combines genome instability, tissue degeneration, cancer predisposition, and premature aging. Primary fibroblasts from A‐T patients exhibit premature senescence when grown at ambient oxygen concentration (21%). Here, we show that reducing oxygen concentration to a physiological level range (3%) dramatically extends the proliferative lifespan of human A‐T skin fibroblasts. However, they still undergo senescence earlier than control cells grown under the same conditions and exhibit high genome instability. Comparative RNA‐seq analysis of A‐T and control fibroblasts cultured at 3% oxygen followed by cluster analysis of differentially expressed genes and functional enrichment analysis, revealed distinct transcriptional dynamics in A‐T fibroblasts senescing in physiological oxygen concentration. While some transcriptional patterns were similar to those observed during replicative senescence of control cells, others were unique to the senescing A‐T cells. We observed in them a robust activation of interferon‐stimulated genes, with undetected expression the interferon genes themselves. This finding suggests an activation of a non‐canonical cGAS‐STING‐mediated pathway, which presumably responds to cytosolic DNA emanating from extranuclear micronuclei detected in these cells. Senescing A‐T fibroblasts also exhibited a marked, intriguely complex alteration in the expression of genes associated with extracellular matrix (ECM) remodeling. Notably, many of the induced ECM genes encode senescence‐associated secretory phenotype (SASP) factors known for their paracrine pro‐fibrotic effects. Our data provide a molecular dimension to the segmental premature aging observed in A‐T patients and its associated symptoms, which develop as the patients advance in age. [ABSTRACT FROM AUTHOR]

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Coal spontaneous combustion (CSC) is one of the main sources of greenhouse gases (GHGs) emission. In order to understand the GHGs emissions law of the heating and quenching processes in the coal low-temperature oxidation stage, three kinds of coal samples with different degrees of metamorphism were selected to investigate the influence of particle size and oxygen concentration on GHGs emissions. Compared with the heating process, the greenhouse effect of CSC under different inerting conditions was determined. The results showed that the CO2 and CH4 were the mainly GHGs in the initial stage of the coal oxidation, which were emitted from the oxidation and desorption of coal, while the particle size of coal displayed the opposite effect on GHGs. By comparison with the heating process, the average emission factor and total emission of CO2 of 1/3 JM, the average emission factor and total emission of CH4 of HM with 21% O2 were higher in the quenching process. Meanwhile, with the decrease in oxygen concentration, the emission rate, average emission factor and total emission of GHGs decreased, and the greenhouse effect of CSC became weaker. Among them, the highest inerting rates of GHGs of HM, 1/3 JM and WYM reached 81.5%, 64.8% and 77.7%, respectively. In addition, the oxygen concentration was linearly positively correlated with the total emissions of CO2 and CH4, and conformed to the quadratic polynomial function with the equivalent CO2 emission factor. However, due to the strong displacement effect of N2, the emission rate, average emission factor and total emission of CH4 of WYM and 1/3 JM with 0% O2 were higher than those with 7% O2, and it is shown that inert gases can weaken the coal oxidation, diminished GHGs emissions, reduced the greenhouse effect of CSC on the environment, and enhanced the desorption of gases in coal. The research results have important practical significance for improving the incomplete emissions of GHGs in the low-temperature oxidation process, and evaluating the emission reduction effect of CSC prevention. [ABSTRACT FROM AUTHOR]

To investigate the release characteristics of potassium during biomass combustion, experimental studies were conducted on three typical biomass fuels in a reactor with a fixed-bed system. The effects of fuel type, combustion temperature, exposure time, oxygen concentration, and water-washing pretreatment were evaluated. The results show that the K release ratio in corn straw increases with the increment in exposure time when the temperature is between 700 and 900 °C. When burned at 900 °C for 40 min, 17.73% of K is released in the volatile combustion stage, while only 2.62% is released in the char combustion stage. When burned at 700–900 °C, the K release ratios in both corn and wheat straw improve slightly with the elevation in oxygen concentration. Water washing significantly reduces the ratio and the amount of K release from corn straw during combustion. The effect of temperature and atmosphere on K release from the water-washed sample is similar to that for the raw sample. [ABSTRACT FROM AUTHOR]

The demand for natural cosmetics has steadily increased in recent years. However, challenges occur especially in quality preservation regarding oxidative spoilage of natural cosmetic products, as the use of synthetic preservatives and antioxidants is limited. Therefore, it is important to find nature-based ingredients to ensure shelf life in natural cosmetic formulations. As a result, potential is seen in the use of plant-based antioxidant extracts. The aim of this work was to determine the suitability of the method combination by measuring the antioxidant activity, oxygen concentration, and volatile oxidation products via gas chromatography (hexanal) for the characterization of the influence of some plant extracts on the oxidative stability of natural cosmetic emulsions. Plant extracts of Riesling (Vitis vinifera) pomace, apple (Malus domestica) pomace, coffee (Coffea arabica) grounds, cocoa (Theobroma cacao) husk, and coffee (Coffea arabica) powder extract were incorporated in stable O/W emulsion formulations, while an emulsion without extract functioned as blank. Afterwards, the emulsions were subjected to 3-month accelerated storage tests with and without light exposure. Their oxygen uptake was investigated, and headspace gas chromatography measurements were performed to detect the fatty acid oxidation products formed during oxidative processes in the samples. The results showed that all emulsion samples under light exposure had a higher oxygen uptake and an increase in the characteristic fatty acid oxidation products compared with those stored under light exclusion. However, differences in oxygen uptake under light exposure were observed depending on the plant extract. Therefore, for O/W emulsions, the daily oxygen consumption rate correlated exponentially with the antioxidant activity, and the hexanal concentration correlated linearly with the daily oxygen consumption rate. [ABSTRACT FROM AUTHOR]

Background: Clinicians favour low oxygen concentrations when resuscitating preterm infants immediately after birth despite inconclusive evidence to support this practice. Prospective meta‐analysis (PMA) is a novel approach where studies are identified as eligible for inclusion in the meta‐analysis before their results are known. Aims: To explore whether high (60%) or low (30%) oxygen is associated with greater efficacy and safety for the initial resuscitation (immediately after birth) of preterm infants born at <29 weeks' gestation. Methods: We will conduct a prospective meta‐analysis (PMA) with individual participant data (IPD). We will perform a systematic search to identify ongoing RCTs including infants <29 weeks' gestation randomised to high (60%) or low (30%) oxygen for initial resuscitation after birth. IPD will be sought for all infants randomised for the purpose of meta‐analysis. We will employ a one‐stage random‐effects approach to IPD meta‐analysis. Potential heterogeneity and the differential effect of high or low oxygen will be explored through subgroup and interaction analyses. The primary outcome of this study is all‐cause mortality prior to hospital discharge. There will be a follow‐up analysis of neurodevelopmental outcomes once available. Results/Conclusion: The results of neonatal outcomes at hospital discharge are expected by 2025, and neurodevelopmental outcomes by 2027. [ABSTRACT FROM AUTHOR]

In this study, a ground-based washing inerting (GBWI) method was proposed, and the application of GBWI in the field of fire prevention and explosion suppression of unmanned aerial vehicle (UAV) fuel tanks was studied using a volume of fluid (VOF) two-phase flow model at a given typical flight envelope. The variation in oxygen concentration in tank ullage during flight was calculated considering the entrance of ambient air and the escape of dissolved oxygen from the fuel. The results indicate that the oxygen concentration in the ullage increases with increasing initial oxygen concentration in the ullage and the initial fuel load after GBWI. In the climb and cruise stages, the oxygen concentration in the ullage increases slowly, while in the tactical descent stage, the oxygen concentration in the ullage increases rapidly, easily exceeding the limiting oxygen concentration (LOC) of aviation fuel combustion. To expand the application range of GBWI, an optimization scheme of nitrogen filling protection was proposed so that the GBWI could meet the requirements of an inert tank at different fuel loads and initial oxygen concentrations in the ullage. Compared with a traditional on-board inert gas generation system (OBIGGS), the optimized GBWI method could greatly reduce the fuel compensation loss and improve the maneuverability of UAVs at the same time. [ABSTRACT FROM AUTHOR]

Post fuel is injected to avoid plugging of diesel particulate filters (DPF). However, at advanced post fuel injection timings, the post fuel is partially oxidized in the cylinder under the high temperature conditions and the hydrocarbon supplied to DOC is not sufficient to regenerate the DPF. In this paper, partial oxidation phenomena at advanced post fuel injection timings were investigated with an engine and a high pressure-temperature optical constant volume chamber. In the engine experiments, the oxidation ratio of the post fuel was calculated from the exhaust gas composition. When the post fuel is injected at 30 CA ATDC, 83% of the post fuel is oxidized, however when the injection timing is 60 CA ATDC, the oxidation ratio of the post fuel becomes 2.2% and there is a 40.9% fuel loss mostly due to oil dilution. The reaction speed, in-cylinder temperature, and oxygen concentration (mol/m3) at the post fuel injection timing are related to the partial oxidation ratio of the post fuel. In the experiments with the constant volume chamber, the spray behaviors at the post fuel injections were observed. The ignition delay becomes longer with lower in-cylinder temperature and lower oxygen concentration, and the spray dilution of the post fuel during the ignition delays affects the heat release and the location where the partial oxidation in the chamber occurs. Based on the experimental data of engine speed, oxygen concentration, and in-cylinder temperature at the start of post fuel injection, an experimental formula for the post fuel oxidation ratio based on the Arrhenius equation was suggested by multiple regression analysis of the engine test data. [ABSTRACT FROM AUTHOR]

Purpose: Determining the variation law of the oxygen concentration in the ullage space of the fuel tank is the key to the design of the inert system. Among various factors affecting the oxygen concentration in the ullage space of the fuel tank, the temperature difference between day and night shows particular importance while relevant analysis and calculation are scarce. Design/methodology/approach: This study establishes a theoretical simulation model of the central wing fuel tank of an aircraft according to the relevant provisions of day-night temperature variation in FAR25 airworthiness regulations, verifies the model with the existing experimental data and discusses the corresponding relationship between the oxygen concentration in the ullage space of the fuel tank and the day-night temperature difference. The influence of day and night temperature difference, fuel type, fuel load rate, initial oxygen concentration, dissolved oxygen evolution and other factors on the oxygen concentration in the ullage space of the fuel tank were analyzed, and the limit of initial oxygen concentration of the fuel tank before the shutdown at night meeting the requirements of the airworthiness provisions was proposed. Findings: The results show that the temperature difference between day and night, fuel load rate, initial oxygen concentration and other factors have different effects on the oxygen concentration in the ullage space of fuel tank. The initial oxygen concentration limit before shutdown shall be 2% below the 12% oxygen concentration stipulated by FAA. Research limitations/implications: The research results in this paper will be of good reference value to the design of the inert system and the calculation of the flammability exposure evaluation time. This paper aims to be good reference of the design of the inert system and the calculation of the flammability exposure evaluation time. Originality/value: The research results of this paper can provide practical guidance for the current civil airworthiness certification work. [ABSTRACT FROM AUTHOR]

The formation of embryoid bodies (EBs) from human pluripotent stem cells resembles the early stages of human embryo development, mimicking the organization of three germ layers. In our study, EBs were tested for their vulnerability to chronic exposure to low doses of MeHgCl (1 nM) under atmospheric (21%O2) and physioxia (5%O2) conditions. Significant differences were observed in the relative expression of genes associated with DNA repair and mitophagy between the tested oxygen conditions in nontreated EBs. When compared to physioxia conditions, the significant differences recorded in EBs cultured at 21% O2 included: (1) lower expression of genes associated with DNA repair (ATM, OGG1, PARP1, POLG1) and mitophagy (PARK2); (2) higher level of mtDNA copy number; and (3) higher expression of the neuroectodermal gene (NES). Chronic exposure to a low dose of MeHgCl (1 nM) disrupted the development of EBs under both oxygen conditions. However, only EBs exposed to MeHgCl at 21% O2 revealed downregulation of mtDNA copy number, increased oxidative DNA damage and DNA fragmentation, as well as disturbances in SOX17 (endoderm) and TBXT (mesoderm) genes expression. Our data revealed that physioxia conditions protected EBs genome integrity and their further differentiation. [ABSTRACT FROM AUTHOR]

Copyright of Mining & Metallurgy (10057854) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Six groups of cellulose-water-oxygen simulation models with oxygen concentrations of 0%, 2%, 4%, 6%, 8%, and 10% were established by molecular dynamics software to analyze the effect of oxygen concentration on the mechanical properties of wood cellulose during water vapor heat treatment in terms of the number of hydrogen bonds, the diffusion coefficient of water molecules, the mean square displacement of cellulose chains, and mechanical parameters. The results showed that the diffusion coefficient of water molecules increased steadily as oxygen concentration increased, which affected cell size and density to some extent. The mean square displacement of the cellulose chain at a higher oxygen concentration was larger than at a lower oxygen concentration, indicating that the cellulose chain became more unstable at high oxygen concentration. This trend was consistent with the amount of hydrogen bonds inside the cellulose chains. The analysis of mechanical parameters showed that Young's modulus and shear modulus showed a trend of increasing and then decreasing with increasing oxygen concentration, and wood cellulose had good resistance to deformation and rigidity at 2% oxygen concentration. Therefore, during the heat treatment of wood, appropriately increasing the oxygen concentration will potentially improve the rigidity and distortion resistance of wood. [ABSTRACT FROM AUTHOR]

Residual coal is easily submerged and damaged by groundwater. In the course of mining underlying coal seam, coal belonging to the overlying gob area tends to spontaneously combust during draining water. To explore the effect of micro-functional group transformation in immersed coal on the coal spontaneous combustion (CSC) traits during the low-temperature oxidation process (LTO), the migrant law of special functional groups under varying oxygen concentration (Co) of immersed coal was discussed by infrared spectroscopy. The endothermal and exothermal properties of the function group inside of coal were studied via thermal analysis. It is shown that the higher Co, the more oxygenic function groups on the soaked, and by contrasted with the Co of 18% the 14% has a small increase and the chain length is shortened. The temperature increment together with the Co content determines the functional group content, the pyrolysis process produces some function group. The lower the Co, endothermic coefficient decreases and endothermic temperature increases, the higher the ignition temperature of coal oxy-combustion, the lower the total heat release. And the speed of the oxygen-absorbing weight gain and the conversion of the functional group would be improved followed by the burnout temperature rising. Below 14% Co, the oxidative combustion process will be greatly inhibited. Those findings complement a theoretical basis for preventing long-term water-soaked coal oxidative spontaneous combusting in shallow buried coal seams. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) techniques such as laser powder bed fusion (LPBF) and directed energy deposition (DED) are viable methods to produce large-size bulk metallic Glass (BMG) components. Even though BMGs with low glass forming abilities (GFA) can potentially be manufactured via AM, the resultant build undergoes partial devitrification, structural relaxation, cracking, or picks up oxygen (O). O pick-up is a serious issue for AM fabricated BMGs as it causes embrittlement and affects its potential use as a structural material. Here, a detailed review of the O pick-up in BMGs during AM fabrication is provided. The effect of O on the propensity of crystal nuclei formation and the glass forming ability of BMGs is critically discussed. Thereafter, the effect of on the mechanical properties of BMGs, and how it affects its structural performance are reviewed. Above a certain threshold, which could be composition-specific, O improves the strength of the BMG but diminishes its fracture, fatigue, and plasticity. These discussions will lead to the formulation of some future directions of research in AM fabrication of BMGs that have both scientific and technological relevance. [ABSTRACT FROM AUTHOR]

To study the transformation and release of fuel K, the combustion of corn stalk and wheat straw were performed in a reactor with a fixed bed between 400–1000°C. Measurements of weight and elemental composition, chemical fractionation analysis, and low‐temperature ashing coupled with X‐ray diffraction (XRD) analysis were conducted on biomass and residual samples. The effects of biomass species, temperature and duration time of combustion, oxygen concentration, and pretreatment of water washing were evaluated. The results show that compared with wheat straw, corn stalk has a lower K release, which is much more sensitive to the combustion temperature than to the oxygen concentration. The inorganic potassium occurs as KClO3 and KClO4 in wheat straw and KCl and KClO4 in corn stalk. K2SO4 appears through sulphation of KCl as combustion happens at 800°C or above. When the combustion temperature reached 900°C for corn stalk and 1000°C for wheat straw, some KCl changed into K2Si2O5, which contains insoluble K. K2Ca(SO4)2 appears as corn stalk and wheat straw are burnt at 1000 and 900°C, respectively. Along with the proceeding of wheat straw combustion, more ion‐exchangeable and water‐soluble K transform to the insoluble K with the increasing temperature. The pretreatment of water washing removes nearly all the water‐soluble K from the corn stalk and significantly decreases the K release from 3.26–0.27 mg g−1 in quantity and from 26.74%–14.84% in ratio at 1000°C, respectively. [ABSTRACT FROM AUTHOR]