Actual Oxygen Consumption Research Articles

An aeration requirements calculating method based on BOD5 soft measurement model using deep learning and improved coati optimization algorithm

Conventionally, the supply-side is over-aerated to meet the oxygen demand of biological wastewater treatment in wastewater treatment plants (WWTPs). Such systems do not consider the various influent loadings and actual oxygen consumption. It cannot respond effectively to fluctuating influent, resulting in unnecessary aeration and energy wastage. In this study, we developed a novel approach to calculate aeration requirements in real time. Firstly, the oxygen demand formula for biological nitrogen and phosphorus removal is modified by considering realistic factors (temperature, oxygen partial pressure and so on) to construct the aeration demand formula. Then, to address the problem that BOD5 in aeration formula is difficult to measure in real time, a novel hybrid model integrating Fuch mapping, reverse learning strategy, Coati Optimization Algorithm (COA), and Backpropagation Artificial Neural Network (BP-ANN) is proposed in this study. Finally, aeration requirements are calculated based on real-time water quality data. Experimental results show that the ICOA-BP model with 9 neurons in hidden layer predicted the optimum BOD5 concentration by achieving a 25.146 mean absolute error and a 0.735 coefficient of determination (all-R2) in all datasets. The optimization led to a 15.164 % aeration savings and 38.942 % energy savings. The proposed method of aeration calculation is automated and intelligent, responding to fluctuating changes in influent quality and reducing unnecessary aeration and energy consumption while meeting the requirements of effluent quality.

Oxygen Consumption with High-Flow Nasal Oxygen versus Mechanical Ventilation- An International Multicenter Observational Study in COVID-19 Patients (PROXY-COVID).

The COVID-19 pandemic led to local oxygen shortages worldwide. To gain a better understanding of oxygen consumption with different respiratory supportive therapies, we conducted an international multicenter observational study to determine the precise amount of oxygen consumption with high-flow nasal oxygen (HFNO) and with mechanical ventilation. A retrospective observational study was conducted in three intensive care units (ICUs) in the Netherlands and Spain. Patients were classified as HFNO patients or ventilated patients, according to the mode of oxygen supplementation with which a patient started. The primary endpoint was actual oxygen consumption; secondary endpoints were hourly and total oxygen consumption during the first two full calendar days. Of 275 patients, 147 started with HFNO and 128 with mechanical ventilation. Actual oxygen use was 4.9-fold higher in patients who started with HFNO than in patients who started with ventilation (median 14.2 [8.4-18.4] versus 2.9 [1.8-4.1] L/minute; mean difference = 11.3 [95% CI 11.0-11.6] L/minute; P < 0.01). Hourly and total oxygen consumption were 4.8-fold (P < 0.01) and 4.8-fold (P < 0.01) higher. Actual oxygen consumption, hourly oxygen consumption, and total oxygen consumption are substantially higher in patients that start with HFNO compared with patients that start with mechanical ventilation. This information may help hospitals and ICUs predicting oxygen needs during high-demand periods and could guide decisions regarding the source of distribution of medical oxygen.

Simulation and application of post-combustion oxygen lance in a top-blown converter

ABSTRACT Flow field characteristics of conventional four-hole oxygen lance and single-flow post-combustion (PC) oxygen lance at steelmaking temperature are studied by numerical simulation, and the industrial trials are carried out in the 120 t top-blown converter to evaluate their metallurgical effects. The simulation results indicate that with the increase of ambient temperature, the potential core length of oxygen jet, jet velocity and radial width (jet diameter) increase. And the jet characteristics of PC oxygen lance are better than those of conventional lance in the radial and axial directions. The industrial trials show that, compared with the conventional lance, using the PC oxygen lance can shorten blowing time by 93 s, reduce actual oxygen consumption by 3.56 m3 t−1 and increase dephosphorization rate by 1.67%. Meanwhile, PC oxygen lance is better for slagging and solves the problem of splashing or drying caused by increasing the oxygen flow rate of the conventional lance.

Potential oxygen consumption and community composition of sediment bacteria in a seasonally hypoxic enclosed bay.

The dynamics of potential oxygen consumption at the sediment surface in a seasonally hypoxic bay were monitored monthly by applying a tetrazolium dye (2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride [INT]) reduction assay to intact sediment core samples for two consecutive years (2012–2013). Based on the empirically determined correlation between INT reduction (INT-formazan formation) and actual oxygen consumption of sediment samples, we inferred the relative contribution of biological and non-biological (chemical) processes to the potential whole oxygen consumption in the collected sediment samples. It was demonstrated that both potentials consistently increased and reached a maximum during summer hypoxia in each year. For samples collected in 2012, amplicon sequence variants (ASVs) of the bacterial 16S rRNA genes derived from the sediment surface revealed a sharp increase in the relative abundance of sulfate reducing bacteria toward hypoxia. In addition, a notable shift in other bacterial compositions was observed before and after the INT assay incubation. It was Arcobacter (Arcobacteraceae, Campylobacteria), a putative sulfur-oxidizing bacterial genus, that increased markedly during the assay period in the summer samples. These findings have implications not only for members of Delta- and Gammaproteobacteria that are consistently responsible for the consumption of dissolved oxygen (DO) year-round in the sediment, but also for those that might grow rapidly in response to episodic DO supply on the sediment surface during midst of seasonal hypoxia.

Estimated versus Actual Oxygen Consumption in Patients Supported with LVADs

PurposeAccurately measured cardiac output (CO) is critical to medical decision making in heart failure patients. The most recent OPTN listing criteria incorporate CO in determining allocation priority. CO is frequently calculated using the Fick equation, in which the key variable of oxygen consumption (VO2) can be directly measured, but is more commonly estimated. The accuracy of these VO2 estimations have been questioned in heart failure patients and have not been validated in LVAD patients. We sought to determine the comparative accuracy of estimated versus measured VO2 in a cohort of LVAD patients using three common formulae.MethodsData were prospectively collected in consecutive LVAD patients who underwent right heart catheterization with direct measurement of resting VO2 using an MGC Diagnostics Ultima CardiO2® gas-exchange analysis cart. We estimated VO2and Fick CO using the formulae proposed by Dehmer et al., LaFarge and Miettinen, and Bergstra et al., and compared these values with directly measured VO2, Fick CO, and thermodilution CO.ResultsFour male patients with HeartMate 3® LVADs underwent right heart catheterization with VO2 measurement. The mean differences in estimated versus measured VO2 and CO were smallest with the formulae proposed by Dehmer et al. and LaFarge and Miettinen, which both modestly underestimated directly measured CO (-0.2 ± 0.3). The error in calculated CO was substantial when utilizing the Bergstra et al. formula (0.5 ± 0.4) and the thermodilution method (-0.8 ± 0.2).ConclusionResting oxygen consumption in LVAD patients, as directly measured by gas-exchange analysis, can be estimated within an acceptable degree of error by the formulae proposed by Dehmer et al. and LaFarge and Miettinen. By comparison, the assumed VO2 by the Bergstra et al. formula appears less accurate in LVAD patients and the degree of error in calculated Fick CO using this equation may be unacceptable for clinical decision making. Accurately measured cardiac output (CO) is critical to medical decision making in heart failure patients. The most recent OPTN listing criteria incorporate CO in determining allocation priority. CO is frequently calculated using the Fick equation, in which the key variable of oxygen consumption (VO2) can be directly measured, but is more commonly estimated. The accuracy of these VO2 estimations have been questioned in heart failure patients and have not been validated in LVAD patients. We sought to determine the comparative accuracy of estimated versus measured VO2 in a cohort of LVAD patients using three common formulae. Data were prospectively collected in consecutive LVAD patients who underwent right heart catheterization with direct measurement of resting VO2 using an MGC Diagnostics Ultima CardiO2® gas-exchange analysis cart. We estimated VO2and Fick CO using the formulae proposed by Dehmer et al., LaFarge and Miettinen, and Bergstra et al., and compared these values with directly measured VO2, Fick CO, and thermodilution CO. Four male patients with HeartMate 3® LVADs underwent right heart catheterization with VO2 measurement. The mean differences in estimated versus measured VO2 and CO were smallest with the formulae proposed by Dehmer et al. and LaFarge and Miettinen, which both modestly underestimated directly measured CO (-0.2 ± 0.3). The error in calculated CO was substantial when utilizing the Bergstra et al. formula (0.5 ± 0.4) and the thermodilution method (-0.8 ± 0.2). Resting oxygen consumption in LVAD patients, as directly measured by gas-exchange analysis, can be estimated within an acceptable degree of error by the formulae proposed by Dehmer et al. and LaFarge and Miettinen. By comparison, the assumed VO2 by the Bergstra et al. formula appears less accurate in LVAD patients and the degree of error in calculated Fick CO using this equation may be unacceptable for clinical decision making.

A systematic assessment of aeration rate effect on aerobic degradation of municipal solid waste based on leachate chemical oxygen demand removal

Aeration is one mainstream technique to accelerate municipal solid waste (MSW) degradation in landfills. The determination of an appropriate aeration rate is critical to the design and operation of a landfill aeration system. In this study, we analyze 132 waste degradation tests reported in forty one studies in the literature. We use L min−1 kg−1 dry organic matter (L min−1 kg−1 DOM) as the uniform unit to quantify the aeration rates in all tests. The first order rate coefficient for chemical oxygen demand (COD) removal in leachate (kCOD) is selected as the parameter to characterize MSW degradation process. We further divide aerobic tests into five aerobic groups base on the respective aeration rates, i.e., <0.02, 0.02–0.1, 0.1–0.3, 0.3–1, and >1 L min−1 kg−1 DOM. With an increase in the aeration rate, the kCOD increases first and then decreases. The aeration rate between 0.1 and 0.3 L min−1 kg−1 DOM has the best enhancement on the kCOD. The kCOD values are not much higher than the anaerobic and semi-aerobic tests when the aeration rates are <0.1 L min−1 kg−1 DOM, because such aeration rates may be lower than the actual oxygen consumption rates. An aeration rate >0.3 L min−1 kg−1 DOM reduces the kCOD likely due to excess water evaporation and ventilation cooling. Among the analyzed results, the aeration rate is the most related to the kCOD in principal component analysis than the other factors, including liquid recirculation and addition, waste total density, waste degradation level, and waste initial temperature.

Material Balance Calculation of Chromium Ore Smelting Reduction and Direct Alloying Process in a Converter

The production process of stainless steel by chromium ore smelting reduction and direct alloying is an important and advanced way to raise the productivity of stainless steel, decrease the production cost, save electric energy and improve the economic profit. The material balance calculation of producing stainless steel crude melts by chromium ore smelting reduction in a 150 t converter is carried out by use of the empirical data and the calculation method of refining plain carbon steel in a converter, according to the blowing conditions of 185 t smelting reduction converter of No.4 steelmaking shop in Chiba Works of JFE Steel. It includes the actual oxygen consumption, furnace gas composition and occurrence amount, mass calculation of stainless steel crude melts and preparation of total material balance table. The absolute error of material balance is -2.859 kg and the relative error is -0.169%. The error is very small, so the material balance calculation can provide certain quantitative basis for determining reasonable design parameters and increasing smelting technology economic indicators.

Experimental study on oxygen consumption rate of residual coal in goaf

In order to research the actual oxygen consumption rate of residual coal in goaf, the heating and oxidizing experiment was conducted respectively on five types of single particle size of coal samples and one hybrid particle size of coal samples by using self-developed CSC-B2 test system. This study measured inlet and outlet oxygen concentration of the oxidation tank, and calculated the oxygen consumption rate of each coal sample at different temperatures. For the residual coal in the same goaf, which is regarded as a hybrid particle size of coal consisting of a variety of single granularity of coal, its oxygen consumption rate is the mass weighted average of the rate of each particle size of coal. Accordingly, this paper established the equation of oxygen consumption rate of hybrid particle size of coal samples, taking into account temperature, granularity and oxygen concentration. Then comparison between the calculated value and the actually measured value of oxygen consumption rate of hybrid particle size of coal samples at different temperatures was conducted. And the results reveal that the calculated value basically coincide with the actually measured one. Moreover, the results prove that the established calculation formula for oxygen consumption rate can be used to accurately calculate the actual oxygen consumption rate of residual coal samples. The achievement of this research is of theoretical and practical significance for learning about the characteristics of coal spontaneous combustion and forecasting the self-ignition of residual coal in goaf.

Process Calculation of Producing Stainless Steel Crude Melts by the Chromium Ore Smelting Reduction in a Converter

The process calculation of producing stainless steel crude melts by smelting reduction in a 150 t converter is carried out for the first time by use of the empirical data and calculation method of refining plain carbon steel in a converter, according to the blowing conditions of 185 t smelting reduction converter of No.4 steelmaking shop in Chiba Works of JFE Steel. Using the self-programming procedure for the processing calculation, the proper coke quantity and a complete set of calculation data for the process of smelting reduction in a converter are obtained, including the batch calculation, the material balance and heat balance calculations. The calculation results show that the increase of PCR can decrease the quantity of coke and actual oxygen consumption considerably, and improve the thermal efficiency of smelting reduction converter. For producing 18 wt% Cr stainless steel crude melts, comparing with the process of electric arc furnace, the process of smelting reduction in a converter can reduce the production cost greatly. The use of the recycled metal containing chromium can shorten blowing time and improve the yield of chromium.

A Comparison of a Speed vs. Grade Incremental Treadmill Protocol on Maximal Oxygen Consumption and Anaerobic Threshold in Division II Cross-Country Runners

PURPOSE: To compare oxygen consumption and anaerobic threshold during a speed incremental treadmill protocol (S) vs. a grade incremental treadmill protocol (G) with equivalent metabolic increments. METHODS: Thirteen subjects (age= 21.7 ± 3 yrs, ht = 172.3 ± 6 cm, bm = 64 ± 6.2 kg) performed two different running protocols in a randomized design with a minimum of 5 days rest between trials. Each stage was 3 minutes long. Trial G was held at a constant speed that coincided with 60–70% of the individual's maximal heart rate reserve while the incline was increased 2% each stage. The S trial began at the matched speed and increased speed equivalent to the predicted metabolic cost of each grade increase from trial G. Metabolic data was obtained using open-circuit spirometry. HR was obtained by telemetry, and finger stick lactate samples were obtained 3-minutes post. Predicted oxygen consumption was derived from the metabolic equations in the ACSM Guidelines (GETP7). RESULTS: Statistical analysis by paired t-test and Pearson correlation were applied to these data at the .05 level of significance. No significant differences were found in predicted VO2 between protocols at any stage. The ACSM equations over-predicted the metabolic demand during every stage of each test (p < .05). No significant difference was found in HRmax or VO2max between protocols. Trial G had a shorter total treadmill time than trial S (13:47 ± 1:28 min:sec vs. 15:06 ± 1:37) and elicited a higher lactate response (10.0 ± 2 mmol in trial G vs. 8.6 ± 1.7 mmol in trial S) (p < .05). CONCLUSION: The ACSM prediction equations significantly over-estimate the actual oxygen consumption by 8.9%. While a grade incremental protocol may provide a more time-efficient test for cross-country runners, a speed protocol readily translates to training workloads. Equivalent results may be obtained in terms of maximal oxygen consumption, anaerobic threshold, and max heart rate using either a speed- or grade-driven protocol.

Getter potentialities of some intermetallics: ZrAl 2, ZrAl 3 and CeNi 5

The oxidation kinetics of single phases ZrAl 2, ZrAl 3 and CeNi 5 have been studied as a function of temperature and fugacity of oxygen to investigate the getter potentialities of these intermetallics. These measurements have been performed using a technique developed in our laboratory for measuring the kinetics of very low oxygen (≥10 −9 moles) consumption by a given sample. Powder samples of ZrAl 2 and ZrAl 3 were thermally cycled first at 8 ppm (0.8 Pa) of oxygen then at 90 ppm (9 Pa). Each cycle was performed with a soak at 1063 K; the results of oxygen consumption rate and the actual oxygen consumption show that ZrAl 2 has greater reactivity when compared to ZrAl 3. Furthermore, ZrAl 2 becomes reactive at lower temperatures (320°C). Small pieces of CeNi 5 were studied at 6 ppm (0.6 Pa) of oxygen. More than one isotherm was performed during each experiment to investigate the oxygen consumption of the intermetallic as a function of temperature. Oxygen consumption data and the relatively low reaction temperature (>300°C) show good potentialities as getter of this intermetallic. In particular, the decrease of the oxygen content in the gas mixture was found to be five orders of magnitude, producing a minimum oxygen partial pressure of 2×10 −6 Pa in the Ar stream for several hours.

Training increases cardiac glucose uptake during rest and exercise in rats.

The effect of chronic exercise on the regional glucose uptake in the left ventricle of the heart was studied in resting and swimming rats using the 2-deoxyglucose method. The left ventricular glucose uptake of untrained resting controls averaged 1.7 +/- 0.1 mumol.min-1.g protein-1 and that of chronically trained resting rats 3.5 +/- 0.3 mumol.min-1.g protein-1 (P less than 0.001). During a 20-min swimming period the glucose uptake rate of untrained rats was 2.3 +/- 0.1 mumol.min-1.g protein-1 and that of trained rats 3.4 +/- 0.3 mumol.min-1.g protein-1 (P less than 0.01). The subendocardial glucose uptake was 25% higher than the subepicardial uptake in the resting control group, whereas no gradient was observed in the other groups. The product of heart rate and blood pressure during swimming increased by 60-70% in the untrained and trained groups. The increase in total left ventricular glucose uptake and its transmural distribution by training seemed to be independent of the actual oxygen consumption or supply of major alternative myocardial substrates.

Correlation between release of reactive oxygen intermediates and inhibition of toxoplasma multiplication in mouse peritoneal and alveolar macrophages and kidney cells after in vitro incubation with obioactin, lonomycin a, muramyl dipeptide, lipopolysaccharide or toxoplasma lysate antigen

The inhibition of Toxoplasma multiplication inside cells does not correlate with an enhanced release of oxygen intermediates except in the case of peritoneal macrophages treated with Obioactin. The inhibition observed in alveolar macrophages treated with Obioactin, in kidney cells treated with Obioactin or lonomycin A and in peritoneal macrophages treated with lonomycin A was not accompanied by an increment of release of oxygen intermediates. Lipopolysaccharide (LPS) and muramyl dipeptide (MDP) enhanced the release of toxic oxygen intermediates in peritoneal macrophages, but did not have any toxoplasmacidal effect. Adenosine triphosphate (ATP) content increased during Obioactin, MDP or Toxoplasma lysate antigen (TLA) treatment. The actual oxygen consumption of the peritoneal macrophages treated with Obioactin increased dose dependently, but that of TLA-, lonomycin A- or MDP-treated cells did not change. These results suggest that the relationship between the intracellular killing of Toxoplasma protozoa and the release of oxygen intermediates differs according to the cells and/or the stimuli, and that the cellular mechanism of Toxoplasma killing in the peritoneal macrophages treated with Obioactin involves an energy-dependent mechanism.

Technique to Give Relevance to Calculated Oxygen Transfer During Cardiopulmonary Bypass

A technique to give relevance to results of oxygen transfer calculation during total cardiopulmonary bypass is presented. An accurate calculation scheme to quantitate total blood oxygen transfer is outlined. Clinical relevance is given to the oxygen transfer calculation result by reporting the value as a percent of an expected oxygen transfer rate. An expected oxygen transfer value is predicted from large population metabolic rate study results employing patient sex, age, body surface area, and temperature. Calculating the percent of expected oxygen consumption value will benefit the perfusionist by increasing the validity of CPB management decisions. The calculation of actual oxygen consumption will aid the perfusionist in selecting an appropriate artificial oxygenator ventilation rate and patient blood flow.

Oxygen consumption during development and aging of the nematode Caenorhabditis elegans

1. 1. The oxygen consumption was measured in all four juvenile stages, the reproductive stage and the aged postreproductive stage of the free-living nematode Caenorhabditis elegans. using the Cartesian diver method. 2. 2. The uptake of oxygen as a function of body weight was VO 2 = 1.66 W 0.70 for all stages except the aged stage and VO 2 = 1.62 W 0.58 when both first stage juveniles and aged organisms were excluded ( VO 2 = nl O 2/μg·h; W = wet weight). 3. 3. The metabolic rate ( VO 2/ W) was significantly lower in both first stage juveniles and aged adults. This is ascribed to utilization of fat stores by way of the glyoxylate cycle during embryogenesis and early morphogenesis and to a general failure of the metabolic machinery during senescence. 4. 4. A comparison of the actual oxygen consumption with the amount of oxygen available to the nematodes by diffusion through the cuticle showed that the weight-specific coefficient b (0.70 or 0.58) could not be explained by decreasing ability to provide oxygen to body tissues with increasing worm size. 5. 5. It is suggested that ATP dependent activities which occur at the cell surface might greatly determine the magnitude of the weight-specific coefficient in nematodes.

Reassessment of aerobic metabolism in amphibians during activity

1. Activity oxygen consumption rates (\(\dot V_{{\text{O}}_2 } \) max) were determined for a variety of amphibians using both electrical and manual stimulation to elicit and maintain activity. The suitability of manometric measurement of\(\dot V_{{\text{O}}_2 } \) max was also evaluated. 2. \(\dot V_{{\text{O}}_2 } \) max (units, ml/g·h) for three minute activity periods induced by manual stimulation were:Hylaregilla, 1.06±0.10;Hyla cadaverina, 1.25±0.14;Batrachoseps attenuatus, 0.82±0.08;Ensatina eschscholtzi, 0.37±0.6; andAneides lugubris, 0.70±0.25.\(\dot V_{{\text{O}}_2 } \) max was 4 to 6 times greater than previously reported values. In all species,\(\dot V_{{\text{O}}_2 } \) during activity was greater than\(\dot V_{{\text{O}}_2 } \) during recovery (Tables 1, 2). 3. \(\dot V_{{\text{O}}_2 } \) in burst activity (3 min) is about 20% greater than\(\dot V_{{\text{O}}_2 } \) in sustained activity (30 min) inRana pipiens (Fig. 1). VO2max was 3 times greater than previously reported values. 4. Electrical stimulation can lead to physiological impairment of aerobic metabolism as evidenced by a decline in\(\dot V_{{\text{O}}_2 } \) with increasing stimulus duration and frequency (Table 1). Electrical stimulation can also lead to errors in\(\dot V_{{\text{O}}_2 } \) as a result of electrolytic gas generation (Fig. 2). 5. Manometric measurement of\(\dot V_{{\text{O}}_2 } \) can seriously underestimate actual oxygen consumption rates because of temperature transients, resulting from both biological and electrical heat production (Fig. 2). Temperature transients also lead to an apparent delayed development of\(\dot V_{{\text{O}}_2 } \) after the activity about.