Background The change in venous oxygen saturation occurs earlier, and even its reduction is faster than arterial oxygen saturation. The aim of this study was to validate SvO2 and PvO2 for O2 content measurement in children hospitalized with respiratory distress. Materials and Methods In this cross-sectional study, 80 children who were admitted with respiratory distress were included in the study according to the study inclusion and exclusion criteria. Baseline characteristics such as age and gender were recorded in the data collection form, designed by the researcher. In order to determine the amount of SaO2 and PaO2 the arterial blood sample was prepared, venous blood sample was prepared to determine the amount of hemoglobin, SvO2 and PvO2. The gold standard for the determination of O2 content was the arterial blood sample. All samples were examined by a blood gas analyzer and then calculated using the formula of O2 content values. For SvO2 and PvO2 validation, we used diagnostic analysis methods including sensitivity, specificity, positive and negative predictive values. Cut-point value for SvO2 and PvO2 were 76. 50 and 44. 30, respectively. Results In this study, the patients’ mean age was 5. 15 ± 4. 20 years. 62. 5% (n=50) were male and 38. 5% (n=30) were female. The values of arterial and venous O2 content were 14. 13 ± 3. 05 and 11. 95 ± 3. 04 from a total of 80 patients. SvO2 and PvO2 for measuring O2 content had a sensitivity of 80. 5 and 71. 80%, respectively, and specificity of 80. 5 and 78%, respectively. Conclusion SvO2 and PvO2 have good validity for evaluating O2 content in patients admitted to PICU. So that SvO2 had a sensitivity and specificity of over 80%, and PvO2 had a sensitivity and specificity of over 70%.

This paper reports a CFD modeling study on the possibility of using high temperature and low oxygen content exhaust gases as oxidant for combustion in an industrial furnace by a written computer program. Under these conditions, the predicted results for the flow and heat transfer properties are compared with those under the several cases of conventional and highly preheated and diluted air combustion (HPDAC) conditions. Although the calculation procedure is a two dimensional one with the vorticity and stream function as the main hydrodynamic variables; its results can yet be also valid for the three dimensional case. Because of the weakness of the standard or other traditional k-e models in predicting the spreading rate of axisymmetric jets, and also for the sake of economy and lack of boundary conditions, here the turbulent transport properties are obtained from an algebraic formula. An infinitely single-step chemical reaction (physically controlled) and a model known as "four flux" are considered as combustion and radiation models, respectively. The qualitative and quantitative verification of high temperature and low oxygen content air/exhaust gases combustions and conventional (low and high air temperature) combustions results have been checked and compared, respectively, with those reported in the literature. Finally, in this investigation three modified concepts and new formulas have been proposed and used to define the gas temperature uniformity, the chemical flame size and the maximum flame temperature as the HPDAC’S main unique features achievement criteria.

The possible ductility troughs of tough pitch copper containing various oxygen contents were identified to determine the safe and unsafe thermomechanical processing domains. Tensile and compression tests were conducted in temperature range of 300-800°, C. The critical strain of single/multiple peaks dynamic recrystallization decreased by increasing oxygen content up to 220 ppm, and again increased with further increment up to 390 ppm. The non-uniform elongation region increased by increasing the temperature, and above 500°, C, it was the dominant portion of the tensile curves. The long post-uniform elongation was attributed to the occurrence of dynamic recrystallization which increased the resistance of the material to localized necking. Two ductility troughs (unsafe thermomechanical processing regions) were recognized at temperatures of 400±, 50°, C and 600±, 50°, C. The ductility drop regions shifted to lower temperatures with an increase in the strain rate. The variation of the oxygen content, however, did not have significant effects on the position of ductility drops. The current work also explores the fracture surface characteristics of the tensile tested specimens.

The influence of initial moisture content on wood decay at different levels of atmospheric oxygen concentration was studied. Three fungi, Coriolus versicolor (C. versicolor) a white rot, Coniophora puteana (C. puteana) a brown rot, and Chaetomium globosum (C. globosum) a soft rot, were chosen. The mycelia of the fungi were inoculated in to mini blocks of Fagus sylvatica (beech) and Pinus sylvestris (Scots pine). Incubation was conducted under four levels of oxygen concentration (1,5,10, and 21% O2) at 22o C. At low oxygen concentrations, an increase of moisture content had a negative effect on the wood decay process by both the Basidiomycetes (C. versicolor and C. puteana) in Scots pine and beech. In air, the effect of initial moisture content on wood decay by these fungi depended on the characteristics of the fungi and the wood species (such as fungal biology and physiology). When C. globosum was used as a colonizer, increasing moisture content generally increased weight loss in the wood blocks (especially in beech). When the moisture content in the wood blocks was increased, more sporulations by C. globosum were also observed on the wood samples. However, the role of oxygen in inceasing wood decay was more important than the moisture content effect.

Rotating detonation engines (RDEs) are an advanced propulsion technology utilizing detonation combustion. RDEs have shown significant potential for substantially enhancing the performance of conventional propulsion systems due to their inherent advantages such as rapid energy release, high thermal efficiency, and a compact reaction zone. Based on these strengths, we conducted experimental investigations of a disk-shaped rotating detonation engine to examine the influences of the oxygen content on the operation characteristics of the engine. The results demonstrate that oxygen enrichment significantly altered the evolution process of rotating detonation waves (RDWs), with dual-wave modes exhibiting higher initiation probability under oxygen-enriched conditions. The results of a quantitative analysis revealed that increasing oxygen content of 21% to 30% increased the velocity of the detonation wave by 11-17% for a single-wave mode and 5-7% for a dual-wave mode. The results of parametric studies demonstrate that increased mass flow rate enhanced the propagating stability of rotating detonation waves, which reduced fluctuations in their parameters. Increasing oxygen content conversely decreased the RDWs’ propagation stability, particularly at low flow rates in single-wave mode. Increasing the oxygen content facilitated the formation of multiple waves, which reduced critical mass flow rate as well as the lean limit of the equivalent ratio for multi-wave modes. Furthermore, oxygen enrichment markedly diminished the lean limit of engine’s operation equivalent ratio, which broadened the stable operating envelope. In contrast with pure air, the lean operation limit of equivalent ratio declined by roughly 25%-59% under oxygen-enriched air conditions. The results of this study demonstrate that oxygen content critically influences the RDWs’ propagation mode in disk-shaped structure as well as the parameters of the detonation waves and the engine’s operation envelope of the engine. These findings offer a deeper understanding of rotating detonation wave propagation and establish a foundation for advancing rotating detonation combustion applications.