Saturated Oxygen Concentration Research Articles

Changes in physicochemical parameters of the alpine/mountain stream influenced by summer flash flood in Tatra Mountains (Western Carpathians)

taChanges to the physicochemical parameters of water in alpine/mountain streams can provide evidence of ongoing natural and anthropogenic processes in their catchment. In this study, we analysed a mountain stream (Javorinka) on the north-eastern side of the Tatra Mountains (Western Carpathians), which is minimally influenced by human activity. The stream was monitored weekly for 5 years (2017–2021) and evaluated for its seasonal variations in physicochemical parameters. These seasonal variations were influenced by the large summer flash flood in July 2018. We hypothesise that floods are essential for the oligotrophic profile of alpine/mountain streams. To support this idea, our main objective was to compare the seasonal trends of the main physicochemical parameters in the stream before and after floods or periods of high flow. We found evidence to support our hypothesis. For example, there was a significant decrease in the chemical consumption of oxygen and ammonia, and, conversely, an increase in the ratio of saturated oxygen and nitrate concentrations. Stream bed erosion also resulted in increased phosphates (over the next 2 years) and high enrichment of the water by dissolved solids in the spring. Interestingly outside of the main objectives, we observed a significant decrease in sulphates, especially in the summer and autumn of 2020 and 2021, which may be related to suppressed emissions due to the restriction of the COVID-19 lockdown. The observed trends and their changes therefore support the idea that alpine/mountain streams are excellent indicators of ongoing environmental processes, and that occasional summer flash floods support the oligotrophic profile of the stream system.

Corrosion effect analysis on thermal-hydraulics of LBE/water spiral tube steam generator under oxygen-controlled environment

The advancement of utilizing liquid Lead-Bismuth Eutectic (LBE) as a cooling medium is hindered by its pronounced corrosive properties. The impact of LBE corrosion on the performance of heat exchangers is significant over the long term, however, this aspect has been largely overlooked in previous studies. Historically, there has been a dearth of LBE corrosion models that account for flow accelerated corrosion. Concurrently, precise numerical models and coupling methods for comprehending the interplay between LBE corrosion and thermal-hydraulics have not been developed. Nevertheless, these contents are pivotal for the advancement of liquid LBE cooling mediums. To delve into the flow and heat transfer characteristics of heat exchangers subjected to LBE corrosion, enhancements were made to capture the accelerated removal effect of LBE corrosion flow. Subsequently, a bidirectional coupling model encompassing LBE corrosion and flow heat transfer was formulated. The Computational Fluid Dynamics (CFD) method was employed to simulate the corrosion and flow heat transfer in a spiral tube steam generator under conditions of saturated oxygen concentration and an oxygen-controlled environment. The results indicate that the corrosion of liquid LBE forms an oxidation layer, which hinders the heat transfer in the spiral tube steam generator. This leads to a significant increase in the wall friction coefficient and a decrease in the surface Nusselt number. However, it does not have a significant effect on the water side evaporation process of the spiral tube steam generator. The implementation of an oxygen-controlled environment can effectively reduce the influence of LBE corrosion on the flow heat transfer of the spiral tube steam generator. Especially under high temperature conditions, it can reduce the near wall temperature of LBE change by up to 57.5% and the outlet temperature change by up to 61.5%. The oxygen-controlled environment results in prolonged local hypoxia time, with a more pronounced effect at higher temperatures.

Corrosion behavior of AlCrFeTiNb and AlCrFeTiNb/(AlCrFeTiNb)N coatings in flowing lead–bismuth eutectic alloy with saturated oxygen concentration at 550 ℃

Corrosion behavior of AlCrFeTiNb and AlCrFeTiNb/(AlCrFeTiNb)N coatings in flowing lead–bismuth eutectic alloy with saturated oxygen concentration at 550 ℃

Enhancing oxygen scavenging properties of erythorbic acid through transition metal catalysis

The presence of oxygen in pipelines used in power plants and the oil industry requires vigilant attention and utilization of oxygen scavenging to prevent the deleterious effects of corrosion. This study aims to investigate the efficacy of four transition metal catalysts (manganese, copper, nickel, and chromium) on the effectiveness of erythorbic acid as an oxygen scavenger. The experimental approach involved injecting varying concentrations (5 ppm, 10 ppm, and 20 ppm) of transition metal catalyst solutions with erythorbic acid at concentrations of 20 ppm, 50 ppm, and 100 ppm, while maintaining a controlled temperature of 25 °C and a pH of 9.0 at a saturated oxygen concentration. The outcome of the study demonstrated that nickel and chromium did not improve the oxygen removal rate, while copper exhibited notable results compared to the control catalyst (manganese). Specifically, the copper (I) chloride solution proved to be the most efficient in reducing dissolved oxygen content to levels below 20 ppb.

Natural hypoxic conditions do not affect the respiration rates of the cold-water coral Desmophyllum pertusum (Lophelia pertusa) living in the Angola margin (Southeastern Atlantic Ocean)

Large, well-developed and flourishing reefs dominated by the cold-water coral Desmophyllum pertusum have recently been discovered along the Angola margin in the southeastern Atlantic Ocean living under very low oxygen concentrations (0.6–1.5 mL L−1). This study assessed the respiration rates of this coral in a short-term (10 days) aquarium experiment under naturally low oxygen concentrations (1.4 ± 0.5 mL L−1) as well as under saturated oxygen concentrations (6.1 ± 0.6 mL L−1). We found no significant difference in respiration rates between the two oxygen concentrations. Furthermore, the respiration rates of D. pertusum were in the same order of magnitude as those of the same species living under normoxic conditions in other areas. This work expands the current knowledge on the metabolic activity of cold-water corals under hypoxic conditions, evidencing that low oxygen conditions are not a general limiting factor for the overall distribution of D. pertusum.

Corrosion Behavior of Ti3SiC2 in Flowing Liquid Lead-Bismuth Eutectic at 500 °C.

MAX phases are promising candidate structural materials for lead-cooled fast reactors (LFRs) and accelerator-driven sub-critical systems (ADSs) due to their excellent corrosion resistance in liquid LBE. In this work, one of the typical MAX phases, Ti3SiC2, was exposed to the flowing LBE with a saturated oxygen concentration at 500 °C for up to 3000 h. The corrosion behaviors, including the evolution of the corrosion layer, mechanical properties and wettability, were evaluated via X-ray diffraction, a scanning electron microscope equipped with an energy-dispersive X-ray, a microhardness test and contact angle measurement. The results reveal that a corrosion structure with a duplex layer was formed on the sample surfaces. The outer layer was a diffusion layer, which always remained thin (<3 μm) during the whole test due to the erosion effect caused by the flowing LBE. The inner layer was the stable protective oxide layer, and its thickness increased with exposure time. The growth of the corrosion structure improved the microhardness and reduced the wettability with regard to LBE, which was beneficial to inhibiting further surface corrosion of Ti3SiC2.

Auto-floating oxygenic microalgal-bacterial granular sludge

As an emerging green wastewater treatment technology, the microalgal-bacterial granular sludge (MBGS) process has attracted increasing interest under the current situation of global climate change. However, little information is available for its performance in treating municipal wastewater under outdoor conditions. Thus, this study evaluated the behaviors of MBGS for treating simulated and real municipal wastewater under natural diel conditions. The results showed that a significant accumulation of oxygen bubbles during daily operation led to the auto-floating of the conventional settable MBGS. The removal of organics was relatively stable during day-night cycles, while the removals of total nitrogen and total phosphorus were dependent on the saturated oxygen concentration over 10 mg/L in MBGS system. Furthermore, oxygen bubbles generated by photosynthesis of microalgae (Scenedesmaceae and Cyanobacteria) due to microalgae phototaxis were found to be attached onto the surface of granules, causing the auto-flotation of MBGS. The formation process of the auto-floating oxygenic MBGS was clarified and further analysis suggested that the non-aerated settable MBGS would be able to auto-float at an average outdoor light intensity of 140 μ mol/m2/s. Overall, the auto-floating oxygenic MBGS process was demonstrated to be feasible for real municipal wastewater treatment, even under rainy and cloudy days, advancing the knowledge and adding theoretical basis for its further applications.

Stability and corrosion behavior of AlO<sub><i>x</i></sub> coating on T91 steel and SIMP steel in static liquid Pb-Bi eutectic at 600 ℃

Ferritic/martensitic steels, such as T91 steel and SIMP steel, are chosen as the main candidates of structural materials for the Generation IV lead-cooled fast reactors and accelerator driven system. However, the compatibility between container steel and liquid Pb-Bi eutectic (LBE) at high temperature limits their applications. The corrosion of ferritic/martensitic steels is serious in LBE at 600 ℃. In order to avoid corroding the ferritic/martensitic steels in LBE, it is proposed to coat AlO<sub><i>x</i></sub> (<i>x </i>< 1.5) on the steel surface. The AlO<sub><i>x</i></sub> coating is conducted on T91 steel and SIMP steel by magnetron sputtering. In this exploratory work, the corrosion results of AlO<sub><i>x</i></sub> coating steel are compared with the corrosion results of the uncoated steel in LBE with a saturated oxygen concentration at 600 ℃ for 300 h and 700 h. The results show that the AlO<sub><i>x</i></sub> coating can effectively prevent the iron chromium and oxygen from diffusing, so the oxide scale of the coated steel is thinner than that of the uncoated steel. However, the coating cracks after 700 h corrosion in LBE. Meanwhile, T91 steel and SIMP steel also suffer serious oxidative corrosion, indicating that the coating can protect the substrate from being corroded by 600 ℃ static LBE in a short time. However, the coating cannot keep stable for a long time in LBE at 600 ℃. This may be due to the weak film base bonding force of AlO<sub><i>x</i></sub> coating prepared under the experimental conditions, or a large number of metal aluminum and structural defects existing in AlO<sub><i>x</i></sub> coating. It is needed to further study the stability of AlO<sub><i>x</i></sub> coating in LBE at elevated temperature.

Wetting Behavior of LBE on Corroded Candidate LFR Structural Materials of 316L, T91 and CLAM.

In this work, the wetting behaviors of lead-bismuth eutectic (LBE) on corroded 316L, T91, and CLAM surfaces were studied. The wettability of LBE on virgin and corroded surfaces were tested at 450 °C by using the sessile-drop (SD) method after immersing the samples in LBE with saturated oxygen concentration for 400, 800, and 1200 h at 450 °C. Additionally, the morphology, as well as element distribution of the corrosion structure, were characterized by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the virgin samples of three materials are non-wetting to LBE, and the formation of corrosion structures further reduces the wettability. Besides, the thickness of the corrosion layer formed on the 316L surface grew more slowly than the other two steel, which results in better corrosion resistance of austenitic steel 316L than that of ferritic/martensitic steels T91 and CLAM at 450 °C. Meanwhile, the morphology and distribution of corrosion products are important factors affecting the wettability of the steel surface. The formation of corrosion products with high roughness as well as disorder results in a significant reduction in surface wettability.

Postnatal administration of systemic steroids increases severity of retinopathy in premature infants

Postnatal systemic steroids are known to increase the risk of developing retinopathy of prematurity (ROP). However, whether the total dosage and type of postnatal systemic steroids are related to the development and severity of ROP in premature infants remains unclear. This study was conducted to identify the risk factors for ROP and investigate the relationship between photocoagulation (PC)-demanding severe ROP and the postnatal dosage of any type of systemic steroids. A total of 75 infants born at <28 weeks of postmenstrual age (PMA) were enrolled. The number of PC procedures for ROP was evaluated as the objective variable. This study analyzed the following independent variables: gestational age; birth weight; sex; Apgar scores; duration of mechanical ventilation; duration of nasal intermittent positive pressure ventilation; mean saturation and mean oxygen concentration administration until 36 weeks of PMA; total accumulation dosage of hydrocortisone, dexamethasone, and systemic steroids; dosage number of times of erythropoietin; total dosage of red cell concentrates (RCC); incidence of necrotizing enterocolitis (NEC) and focal intestinal perforation; sepsis; bronchopulmonary dysplasia (BPD); and intraventricular hemorrhage (IVH). Logistic regression was used to estimate the relative risk (odds ratio (OR)) associated with risk factors for PC-demanding severe ROP. Compared with infants in the non-PC group, PC-treated infants had younger gestational age, longer mechanical ventilation periods, and higher dosage of systemic steroids and dexamethasone. Multivariate logistic regression analysis revealed total dosage of systemic steroids as the only risk factor for PC-demanding severe ROP. Based on receiver operating characteristic (ROC) curve analysis, a cutoff value of 8.95mg/kg of postnatal systemic steroid administration was identified as a useful marker to predict PC-demanding severe ROP. By focusing on the method of systemic steroid administration and avoiding excessive doses for infants born at <28 weeks of PMA, preventing the development of severe ROP is possible.

Corrosion properties of Ti3SiC2 and Ti3AlC2 in static liquid lead–bismuth eutectic at 500°C

AbstractFor lead‐cooled fast reactors and accelerator‐driven subcritical systems, the surface corrosion behavior of candidate structural materials in lead–bismuth eutectic (LBE) is a key issue, which determines whether the material is applicable. The candidate materials of two typical MAX phases, Ti3SiC2 and Ti3AlC2, were immersed in static LBE with saturated oxygen concentration at 500°C for up to 3000 h. The corrosion behaviors of Ti3SiC2 and Ti3AlC2 were analyzed by scanning electron microscope, energy‐dispersive X‐ray, X‐ray diffraction, and Raman spectra. The experimental results showed that elements interdiffusion between LBE and sample matrix occurred on both Ti3SiC2 and Ti3AlC2 surfaces, which led to the formation of the diffusion layer. The dominant component of the diffusion layer is PbTiO3, which makes the corroded surface fragile in a stress environment. Besides, there were differences in structures of corroded sample surfaces between Ti3SiC2 and Ti3AlC2. The corrosion layer of Ti3SiC2 consisted of two layers, while only one single layer formed on Ti3AlC2 surfaces. The stable oxide layer consisting of SiO2 and TiO2 can protect Ti3SiC2 samples from further LBE corrosion and maintain the integrity of the surfaces. For Ti3AlC2 samples, it is hard to form a continuous Al2O3 protective layer, thus no stable oxide layer was detected on the corroded surfaces. Compared with Ti3AlC2, Ti3SiC2 showed better corrosion resistance in LBE.

Zooplankton of the low-oxygen waters of Bahia Callao (Central Peru) - with special reference to the reproductive activity of the copepod Acartia tonsa

Zooplankton distribution in the Bahia Callao, a low oxygen bay in Central Peru, was studied during surveys in March (austral summer) and September (austral spring) 2006. In March temperature was higher, but oxygen concentrations were much lower, especially near the sea floor. Zooplankton abundance at 14 repeated stations (March/September = 457/2356 ind. m−3), taxa number (35/97), and community composition changed drastically, but Acartia tonsa was dominant during both surveys. In contrast, abundance of meroplanktonic larvae did not change.The reproductive activity of A. tonsa was studied bi-weekly from November 2005 to August 2007 at a fixed station close to shore (9 m water depth). Population egg production rate ranged from 0.9 to 12.6 eggs female−1d−1 and was significantly related to Chlorophyll a, temperature, and dissolved oxygen. Individual clutch size ranged from 1 to 43 eggs. Egg hatching rate varied from 3.4 to 100%; the lowest values were associated with very low concentrations of dissolved oxygen in the surface layer and red tides. In feeding experiments at saturated oxygen concentrations >30 eggs female−1d−1 were produced, indicating continuous inhibition of egg production in the field. Oceanographic data demonstrate that the bay, and probably also the adjacent shelves, are exposed to frequent environmental changes, which challenge the survival and production of zooplankton and fish. The relationship between seemingly adverse environmental conditions and high biological productivity still needs to be understood.

Corrosion behaviour of Al-added high Mn austenitic steels in molten lead bismuth eutectic with saturated and low oxygen concentrations at 450 ℃

Corrosion tests were performed on newly developed alumina-forming austenitic (AFA) steels in stagnant lead bismuth eutectic (LBE) with saturated and low oxygen concentrations at 450 ℃ for 430 h. The steels exhibited enhanced corrosion resistance to the LBE environments with the increasing of Al content. A continuous and protective Al-rich oxide scale formed on the steel specimens that were exposed to LBE with a low oxygen concentration, whereas a non-protective and stratified oxide scale formed in the oxygen saturated LBE.

Effect of LBE Corrosion on Surface Wettability of Ti&lt;sub&gt;3&lt;/sub&gt;SiC&lt;sub&gt;2&lt;/sub&gt; at 450°C

Due to the excellent properties such as high temperature resistance, corrosion resistance, good heat conduction and plasticity, MAX-phase materials have been considered as one of the candidate materials for cladding and coating material in liquid metal cooled fast reactors. In this paper, the evolution of surface structure and wettability of Ti3SiC2 under short-term LBE corrosion were studied experimentally. The samples were immersed in LBE with saturated oxygen concentration for 100, 300 and 500 h at 450°C. The surface and cross section morphology as well as composition distribution of corrosion samples were analyzed by metallographic microscope, scanning electron microscope (SEM) and energy dispersive X-ray fluorescence spectrometer (EDX). Meanwhile, five-point fitting method was used to determine the contact angle of raw and corroded samples at 450°C. The results showed that the surface smoothness of Ti3SiC2 samples degenerated after LBE corrosion. No stratification was observed in all corroded samples but the transition layer was found in the surface region of corroded samples and its thickness increased with the increase of corrosion time. In the sample corroded for 500 h, the transition layer near the matrix side tended to transform into stable oxidation layer. In addition, the increase of corrosion time will lead to the reduction of LBE wetting on the surface of materials, which can effectively affect heat transfer of the surface.

Rapid coastal deoxygenation due to ocean circulation shift in the NW Atlantic.

Global observations show that the ocean lost approximately 2% of its oxygen inventory over the last five decades 1–3, with important implications for marine ecosystems 4, 5. The rate of change varies with northwest Atlantic coastal waters showing a long-term drop 6, 7 that vastly outpaces the global and North Atlantic basin mean deoxygenation rates 5, 8. However, past work has been unable to resolve mechanisms of large-scale climate forcing from local processes. Here, we use hydrographic evidence to show a Labrador Current retreat is playing a key role in the deoxygenation on the northwest Atlantic shelf. A high-resolution global coupled climate-biogeochemistry model 9 reproduces the observed decline of saturation oxygen concentrations in the region, driven by a retreat of the equatorward-flowing Labrador Current and an associated shift toward more oxygen-poor subtropical waters on the shelf. The dynamical changes underlying the shift in shelf water properties are correlated with a slowdown in the simulated Atlantic Meridional Overturning Circulation 10. Our results provide strong evidence that a major, centennial-scale change of the Labrador Current is underway, and highlight the potential for ocean dynamics to impact coastal deoxygenation over the coming century.

Effect of Cleaning Chemistries on Cobalt: Surface Chemistries and Electrical Characterization

The etching characteristics of ECD cobalt in different cleaning solutions were characterized using four-point probe, spectroscopic ellipsometry, and X-ray photoelectron spectroscopy. 0.05% HF solution with saturated dissolved oxygen concentration was found to result in a substantial etch of ECD cobalt (~5 nm/min). In contrast, cleaning in the SC1 1:4:100 mixture and the formulated mixture led to a significantly lower etch amount, which could be explained by the formation of a passivation layer at the surface. XPS characterization indicated the formation of a cobalt hydroxide at the surface. The electrical evaluation of the DD structure carried out after cleaning using the formulated chemical mixture and subsequent metallization showed good yield for the 22 nm Kelvin vias, testifying an efficient cleaning of the Co surface at the via bottom.

Assessing the fate of explosives derived nitrate in mine waste rock dumps using the stable isotopes of oxygen and nitrogen

Ammonium nitrate (NH4NO3) mixed with fuel oil is a common blasting agent used to fragment rock into workable size fractions at mines throughout the world. The decomposition and oxidation of undetonated explosives can result in high NO3– concentrations in waters emanating from waste rock dumps. We used the stable isotopic composition of NO3– (δ15N- and δ18O-NO3–) to define and quantify the controls on NO3– composition in waste rock dumps by studying water-unsaturated and saturated conditions at nine coal waste rock dumps located in the Elk Valley, British Columbia, Canada. Estimates of the extent of nitrification of NH4NO3 in oxic zones in the dumps, initial NO3– concentrations prior to denitrification, and the extent of NO3– removal by denitrification in sub-oxic to anoxic zones are provided. δ15N data from unsaturated waste rock dumps confirm NO3– is derived from blasting. δ15N- and δ18O-NO3– data show extensive denitrification can occur in saturated waste rock and in localized zones of elevated water saturation and low oxygen concentrations in unsaturated waste rock. At the mine dump scale, the extent of denitrification in the unsaturated waste rock was inferred from water samples collected from underlying rock drains.

Effects of low oxygen concentrations on aerobic methane oxidation in seasonally hypoxic coastal waters

Abstract. Coastal seas may account for more than 75 % of global oceanic methane emissions. There, methane is mainly produced microbially in anoxic sediments from which it can escape to the overlying water column. Aerobic methane oxidation (MOx) in the water column acts as a biological filter, reducing the amount of methane that eventually evades to the atmosphere. The efficiency of the MOx filter is potentially controlled by the availability of dissolved methane and oxygen, as well as temperature, salinity, and hydrographic dynamics, and all of these factors undergo strong temporal fluctuations in coastal ecosystems. In order to elucidate the key environmental controls, specifically the effect of oxygen availability, on MOx in a seasonally stratified and hypoxic coastal marine setting, we conducted a 2-year time-series study with measurements of MOx and physico-chemical water column parameters in a coastal inlet in the south-western Baltic Sea (Eckernförde Bay). We found that MOx rates generally increased toward the seafloor, but were not directly linked to methane concentrations. MOx exhibited a strong seasonal variability, with maximum rates (up to 11.6 nmol L−1 d−1) during summer stratification when oxygen concentrations were lowest and bottom-water temperatures were highest. Under these conditions, 2.4–19.0 times more methane was oxidized than emitted to the atmosphere, whereas about the same amount was consumed and emitted during the mixed and oxygenated periods. Laboratory experiments with manipulated oxygen concentrations in the range of 0.2–220 µmol L−1 revealed a submicromolar oxygen optimum for MOx at the study site. In contrast, the fraction of methane–carbon incorporation into the bacterial biomass (compared to the total amount of oxidized methane) was up to 38-fold higher at saturated oxygen concentrations, suggesting a different partitioning of catabolic and anabolic processes under oxygen-replete and oxygen-starved conditions, respectively. Our results underscore the importance of MOx in mitigating methane emission from coastal waters and indicate an organism-level adaptation of the water column methanotrophs to hypoxic conditions.

Influence of oxide scale on the wettability of LBE on T91 steel

The present work represents an experimental investigation on the wetting behaviour of lead bismuth eutectic (LBE) on corroded T91. Firstly, the T91 samples were exposed to LBE at saturated oxygen concentration for 400h, 1200h and 2000h respectively. Then, the contact angle of LBE on the oxidized T91 steel was measured with the sessile-drop method. In comparison, the contact angle of LBE on bare T91 sample was also measured in the same way. The results showed that corroded T91 steel possess worse surface wettability. The corroded samples were analyzed with scanning electron microscope (SEM). At last, the influence of oxide scale on the wettability was evaluated by analyzing the measuring results of the contact angle and SEM report. The experiment results were discussed in the paper in detail.

Muscle Near-Infrared Spectroscopy Signals versus Venous Blood Hemoglobin Oxygen Saturation in Skeletal Muscle.

The study aimed to examine the relationship between near-infrared spectroscopy (NIRS) signals and venous hemoglobin oxygen saturation (O2Hb%) and venous oxygen concentration (CvO2). Gastrocnemius muscles (GS) in six dogs were surgically isolated and pump perfused. NIRS signals were recorded, and venous blood samples were collected at constant flow rates (control flow, high flow, and low flow) at rest as well as during electrically stimulated tetanic muscle contractions at rates of one contraction per 2 s (1/2 s) and two contractions per 3 s (2/3 s). Similar data were also collected at three different inspired O2 percentages (12%, 21%, and 100%) with constant blood flow. Complete data from five animals were analyzed; all data from one animal were deleted because of erratic oxy-NIRS signals. Venous O2Hb% ranged from 7.6% to 97.5% across the various experimental conditions. After the NIRS signals were normalized to the physiological range, a high linear correlation was seen between the deoxygenated heme signal (HHbMb%) and the venous O2Hb% (R = 0.92 ± 0.05), between the oxygenated heme signal (HbMbO2%) and the venous O2Hb% (R = 0.92 ± 0.03), between the HHbMb% and the CvO2 (R = 0.89 ± 0.06), and between the HbMbO2% and the CvO2 (R = 0.90 ± 0.05). The overall relationships between HHbMb%, HbMbO2%, and venous O2Hb% as well as between HHbMb%, HbMbO2%, and CvO2 were also linear and highly correlated with R values ranging from 0.81 to 0.90. In this controlled canine muscle model, NIRS signals are highly correlated with venous O2Hb% and CvO2 across a wide range of physiological conditions. The practical application of our results is that for an individual muscle or perhaps muscle group, normalized NIRS HHbMb and HbMbO2 signals accurately reflect the mean venous O2 saturation of the interrogated muscle tissue.