Artículos de revistas: "VO2 kinetic"

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Xing, H. C., J. E. Cochrane, Y. Yamamoto y R. L. Hughson. "Frequency domain analysis of ventilation and gas exchange kinetics in hypoxic exercise". Journal of Applied Physiology 71, n.º 6 (1 de diciembre de 1991): 2394–401. http://dx.doi.org/10.1152/jappl.1991.71.6.2394.

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The kinetics of O2 up-take (VO2), CO2 output (VCO2), ventilation (VE), and heart rate (HR) were studied during exercise in normoxia and hypoxia [inspired O2 fraction (FIO2) 0.14]. Eight male subjects each completed 6 on- and off-step transitions in work rate (WR) from low (25 W) to moderate (100–125 W) levels and a pseudorandom binary sequence (PRBS) exercise test in which WR was varied between the same WRs. Breath-by-breath data were linearly interpolated to yield 1-s values. After the first PRBS cycle had been omitted as a warm-up, five cycles were ensemble-averaged before frequency domain analysis by standard Fourier methods. The step data were fit by a two-component (three for HR) exponential model to estimate kinetic parameters. In the steady state of low and moderate WRs, each value of VO2, VCO2, VE, and HR was significantly greater during hypoxic than normoxic exercise (P less than 0.05) with the exception of VCO2 (low WR). Hypoxia slowed the kinetics of VO2 and HR in on- and off-step transitions and speeded up the kinetics of VCO2 and VE in the on-transition and of VE in the off-transition. Frequency domain analysis confined to the range of 0.003–0.019 Hz for the PRBS tests indicated reductions in amplitude and greater phase shifts in the hypoxic tests for VO2 and HR at specific frequencies, whereas amplitude tended to be greater with little change in phase shift for VCO2 and VE during hypoxic tests.(ABSTRACT TRUNCATED AT 250 WORDS)

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Larson, Rebecca D., Monica Barton, John W. Farrell III, Gregory S. Cantrell, David J. Lantis, Christopher D. Black y Carl J. Ade. "Evaluation of Oxygen Uptake Kinetic Asymmetries in Patients with Multiple Sclerosis: A Pilot Study". International Journal of Kinesiology and Sports Science 6, n.º 4 (31 de octubre de 2018): 21. http://dx.doi.org/10.7575/aiac.ijkss.v.6n.4p.21.

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Background of Study: Observations of limb to limb differences (bilateral asymmetry) in leg strength, power, peak oxygen uptake (VO2) and bone mineral density has been reported in individuals with Multiple Sclerosis (MS). Objetives: The purpose of this study was to quantify the magnitude of bilateral asymmetries in oxygen uptake (VO2) kinetics response to single leg cycling (SLC) in relapsing-remitting multiple sclerosis (MS) patients. Methods: Five MSpatients (2 men, 3 women; age 43±7 yrs) performed constant work rate SLC trials to determine VO2 kinetics in each leg. Asymmetry scores were used to quantify the magnitude of the bilateral asymmetries. Results: Significant asymmetries were seen in VO2 peak and parameters of VO2 kinetics. VO2peak asymmetry score was significantly different than 0% (p=0.015). Similarly,significant asymmetry for VO2 kinetic response to exercise as mean response time was observed (p=0.03). In addition the VO2 response to exercise resulted in a significant asymmetry in VO2 deficit between legs (p=0.03). No correlation between EDSS scores and any asymmetry scores existed. Conclusions: These findings provide insight into the potential differences in metabolic perturbation and limb specific symptomatic fatigue within the MS population.

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Buekers, Joren, Jan Theunis, Alberto Peña Fernández, Emiel F. M. Wouters, Martijn A. Spruit, Patrick De Boever y Jean-Marie Aerts. "Box-Jenkins Transfer Function Modelling for Reliable Determination of VO2 Kinetics in Patients with COPD". Applied Sciences 9, n.º 9 (1 de mayo de 2019): 1822. http://dx.doi.org/10.3390/app9091822.

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Oxygen uptake (VO2) kinetics provide information about the ability to respond to the increased physical load during a constant work rate test (CWRT). Box-Jenkins transfer function (BJ-TF) models can extract kinetic features from the phase II VO2 response during a CWRT, without being affected by unwanted noise contributions (e.g., phase I contribution or measurement noise). CWRT data of 18 COPD patients were used to compare model fits and kinetic feature values between BJ-TF models and three typically applied exponential modelling methods. Autocorrelation tests and normalised root-mean-squared error values (BJ-TF: 2.8 ± 1.3%; exponential methods A, B and C: 10.5 ± 5.8%, 11.3 ± 5.2% and 12.1 ± 7.0%; p < 0.05) showed that BJ-TF models, in contrast to exponential models, could account for the most important noise contributions. This led to more reliable kinetic feature values compared to methods A and B (e.g., mean response time (MRT), BJ-TF: 74 ± 20 s; methods A-B: 100 ± 56 s–88 ± 52 s; p < 0.05). Only exponential modelling method C provided kinetic feature values comparable to BJ-TF features values (e.g., MRT: 75 ± 20 s). Based on theoretical considerations, we recommend using BJ-TF models, rather than exponential models, for reliable determinations of VO2 kinetics.

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4

Morton, R. H. "Delayed or accelerated oxygen uptake kinetics in the transition from prior exercise?" Journal of Applied Physiology 62, n.º 2 (1 de febrero de 1987): 844–46. http://dx.doi.org/10.1152/jappl.1987.62.2.844.

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Reported experimental findings are at variance with each other on the question as to whether O2 uptake (VO2) kinetics are delayed, advanced, or remain unaltered in the transition from prior exercise. Critical examination of these studies tend to suggest that not a great deal of reliance can be placed on their evidence in attempting to resolve the question. They seem to display a disregard for the theoretical properties of the VO2 kinetic model used; in some cases incorrect statistical inferences appear to have been made; most are mathematically incomplete; and the experimental designs have not been appropriately chosen so as to examine the whole question of altered VO2 kinetics. These points are detailed and discussed so that future designed experiments obtain sufficient reliable evidence with which to resolve the question.

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Shoemaker, J. K., L. Hodge y R. L. Hughson. "Cardiorespiratory kinetics and femoral artery blood velocity during dynamic knee extension exercise". Journal of Applied Physiology 77, n.º 6 (1 de diciembre de 1994): 2625–32. http://dx.doi.org/10.1152/jappl.1994.77.6.2625.

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The kinetics of femoral artery mean blood velocity (MBV; measured by pulsed Doppler) and whole body oxygen uptake (VO2; measured breath by breath) were assessed from the time constant during the on (tau on) and off (tau off) transients to step changes in work rate between complete rest and dynamic knee extension (KE) exercise. Six healthy men performed 5 min of seated KE exercise, with each leg alternately raising and lowering a weight (10% maximum voluntary contraction) over a 2-s duty cycle. Because kinetic analysis of VO2 kinetics during KE exercise is a new approach, the VO2 responses were also evaluated during the on and off transitions to the more familiar upright cycling exercise in which the magnitude of increase in VO2 and cardiac output was similar to that during KE exercise. During KE exercise, VO2 tau on [mean 72.2 +/- 11.2 (SE) s] was slower than VO2 tau off (33.3 +/- 1.8 s; P < 0.01). Cardiac output, measured with impedance cardiography, was not different for tau on (67.1 +/- 20.0 s) compared with that for tau off (52.9 +/- 7.6 s). Likewise, MBV tau on (34.5 +/- 3.9 s) was not different from tau off (35.3 +/- 3.2 s). During cycling, the VO2 tau on (18.0 +/- 2.4 s) and tau off (30.7 +/- 1.2 s) were both faster than KE VO2 tau on (P < 0.01). Even though the MBV kinetics indicated a rapid adaptation of blood flow during KE exercise, there was a slow adaptation of VO2. A transient hyperemia immediately on cessation of KE exercise, indicated by both MBV and calculated systemic vascular conductance responses, suggested that blood flow might have been inadequate and could have contributed to the delayed adaptation of VO2 at the onset of exercise, although other explanations are possible.

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6

Lin, Xueyan, Wenyue Li, Xuan Pan, Shu Wang y Zhaoyang Fan. "Electrocatalytic and Conductive Vanadium Oxide on Carbonized Bacterial Cellulose Aerogel for the Sulfur Cathode in Li-S Batteries". Batteries 9, n.º 1 (26 de diciembre de 2022): 14. http://dx.doi.org/10.3390/batteries9010014.

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Many transition-metal-oxide-based catalysts have been investigated to chemically bind soluble lithium polysulfides and accelerate their redox kinetics in lithium-sulfur (Li-S) battery chemistry. However, the intrinsic poor electrical conductivities of these oxides restrict their catalytic performance, consequently limiting the sulfur utilization and the rate performance of Li-S batteries. Herein, we report a freestanding electrocatalytic sulfur host consisting of hydrogen-treated VO2 nanoparticles (H-VO2) anchored on nitrogen-doped carbonized bacterial cellulose aerogels (N-CBC). The hydrogen treatment enables the formation and stabilization of the rutile VO2(R) phase with metallic conductivity at room temperature, significantly enhancing its catalytic capability compared to the as-synthesized insulative VO2(M) phase. Several measurements characterize the electrocatalytic performance of this unique H-VO2@N-CBC structure. In particular, the two kinetic barriers between S8, polysulfides, and Li2S are largely reduced by 28.2 and 43.3 kJ/mol, respectively. Accordingly, the Li-S battery performance, in terms of sulfur utilization and charge/discharge rate, is greatly improved. This work suggests an effective strategy to develop conductive catalysts based on a typical transition metal oxide (VO2) for Li-S batteries.

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7

Phillips, S. M., H. J. Green, M. J. MacDonald y R. L. Hughson. "Progressive effect of endurance training on VO2 kinetics at the onset of submaximal exercise". Journal of Applied Physiology 79, n.º 6 (1 de diciembre de 1995): 1914–20. http://dx.doi.org/10.1152/jappl.1995.79.6.1914.

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The rates of increase in O2 uptake (VO2) after step changes in work rate from 25 W to 60% of pretraining peak VO2 (VO2 peak) were measured at various times during an endurance training program (2 h/day at 60% pretraining VO2 peak). Seven untrained males [23 +/- 1 (SE) yr] performed a series of repeated step changes in work rate before training (PRE) and after 4 days (4D), 9 days (9D), and 30 days (30D) of training. VO2 kinetic responses were determined from breath-by-breath data averaged across four repetitions and analyzed using a two-component exponential model. Mean response time (time taken to reach 63% of steady-state VO2) was faster (P < 0.01) than PRE (38.1 +/- 2.6 s) at both 4D (34.9 +/- 2.4 s) and 9D (32.5 +/- 1.8 s) and was faster (P < 0.01) at 30D than at all other times (28.3 +/- 1.0 s). Blood lactate concentrations (after 6 min of cycling) were also lower at 4D and 9D than PRE (P < 0.01) and were lower at 30D than at all other times (P < 0.01). VO2 peak was unchanged from PRE (3.52 +/- 0.20 l/min) at 8D (3.55 +/- 0.20 l/min) but was increased (P < 0.01) at 30D (3.89 +/- 0.18 l/min). Muscle oxidative capacity (maximal citrate synthase activity) was not significantly increased until 30D (P < 0.01). It is concluded that at least part of the acceleration of whole body VO2 kinetics with endurance training is a rapid phenomenon, occurring before changes in VO2 peak and/or muscle oxidative potential.

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8

Hughson, R. L., J. E. Cochrane y G. C. Butler. "Faster O2 uptake kinetics at onset of supine exercise with than without lower body negative pressure". Journal of Applied Physiology 75, n.º 5 (1 de noviembre de 1993): 1962–67. http://dx.doi.org/10.1152/jappl.1993.75.5.1962.

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The kinetics of oxygen uptake (VO2) were observed at the onset of submaximal cycling exercise in seven men and one woman [mean age 22.6 +/- 0.9 (SE) yr] in the upright and supine positions and the supine position with -40 mmHg lower body negative pressure (LBNP). There was no significant difference for peak VO2 and ventilatory threshold between the supine (3,081 +/- 133 and 1,954 +/- 138 ml/min, respectively) and the supine + LBNP positions (3,062 +/- 152 and 1,973 +/- 122 ml/min); however, both were reduced compared with upright exercise (3,483 +/- 200 and 2,353 +/- 125 ml/min). Kinetic analysis applied to six repetitions by each subject indicated a slowing from a mean total lag time (time required to achieve 63% of the difference in VO2 between baseline and new steady state) of 36.3 +/- 2.7 s in upright exercise to 44.1 +/- 3.5 s in the supine position. However, total lag time for the supine + LBNP position (36.0 +/- 2.8 s) did not differ from upright exercise but was significantly faster than supine exercise. These data have been interpreted in support of an O2 transport limitation to VO2 kinetics at the onset of supine exercise that is countered by LBNP, likely through a more rapid increase in perfusion to the exercising muscle at these submaximal work rates.

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9

Wilkerson, Daryl P., Katrien Koppo y Andrew M. Jones. "Pulmonary Vo2 On-kinetic Response To Step Exercise". Medicine & Science in Sports & Exercise 37, Supplement (mayo de 2005): S362—S363. http://dx.doi.org/10.1249/00005768-200505001-01896.

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Wilkerson, Daryl P., Katrien Koppo y Andrew M. Jones. "Pulmonary Vo2 On-kinetic Response To Step Exercise". Medicine & Science in Sports & Exercise 37, Supplement (mayo de 2005): S362???S363. http://dx.doi.org/10.1097/00005768-200505001-01896.

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11

Machado, Fabiana A., >Luiz G. A. Guglielmo, Camila C. Greco y Benedito S. Denadai. "Effects of Exercise Mode on the Oxygen Uptake Kinetic Response to Severe-Intensity Exercise in Prepubertal Children". Pediatric Exercise Science 21, n.º 2 (mayo de 2009): 159–70. http://dx.doi.org/10.1123/pes.21.2.159.

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The objective of this study was to verify the effect of the exercise mode on slow component of VO2 (VO2SC) in children aged 11–12 years during severe-intensity exercise. After determination of the lactate threshold (LT) and peak VO2 (VO2peak) in both cycling (CE) and running exercise (TR), fourteen active boys completed a series of “square-wave” transitions of 6-min duration at 75%∆ [75%∆ = LT + 0.75 × (VO2peak—LT)] to determine the VO2 kinetics. The VO2SC was significantly higher in CE (180.5 ± 155.8 ml • min−1) than in TR (113.0 ± 84.2 ml · min−1). We can conclude that, although a VO2SC does indeed develop during TR in children, its magnitude is considerably lower than in CE during severe-intensity exercise.

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12

Lai, Nicola, Melita M. Nasca, Marco A. Silva, Fatima T. Silva, Brian J. Whipp y Marco E. Cabrera. "Influence of exercise intensity on pulmonary oxygen uptake kinetics at the onset of exercise and recovery in male adolescents". Applied Physiology, Nutrition, and Metabolism 33, n.º 1 (febrero de 2008): 107–17. http://dx.doi.org/10.1139/h07-154.

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The dynamics of the pulmonary oxygen uptake (VO2) responses to square-wave changes in work rate can provide insight into bioenergetic processes sustaining and limiting exercise performance. The dynamic responses at the onset of exercise and during recovery have been investigated systematically and are well characterized at all intensities in adults; however, they have not been investigated completely in adolescents. We investigated whether adolescents display a slow component in their VO2 on- and off-kinetic responses to heavy- and very heavy-intensity exercise, as demonstrated in adults. Healthy African American male adolescents (n = 9, 14–17 years old) performed square-wave transitions on a cycle ergometer (from and to a baseline work rate of 20 W) to work rates of moderate (M), heavy (H), and very heavy (VH) intensity. In all subjects, the VO2 on-kinetics were best described with a single exponential at moderate intensity (τ1, on = 36 ± 11 s) and a double exponential at heavy (τ1, on = 29 ± 9 s; τ2, on = 197 ± 92 s) and very heavy (τ1, on = 36 ± 9 s; τ2, on = 302 ± 14 s) intensities. In contrast, the VO2 off-kinetics were best described with a single exponential at moderate (τ1, off = 48 ± 9 s) and heavy (τ1, off = 53 ± 7 s) intensities and a double exponential at very heavy (τ1, off = 51 ± 3 s; τ2, off = 471 ± 54 s) intensity. In summary, adolescents consistently displayed a slow component during heavy exercise (on- but not off- transition) and very heavy exercise (on- and off-transitions). Although the overall response dynamics in adolescents were similar to those previously observed in adults, their specific characterizations were different, particularly the lack of symmetry between the on- and off-responses.

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Venturelli, Massimo y Federico Schena. "Vo2 Kinetic During Arm And Leg Exercise In Elderly Adults". Medicine & Science in Sports & Exercise 39, Supplement (mayo de 2007): S424. http://dx.doi.org/10.1249/01.mss.0000274675.69387.62.

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14

Müller, A., G. Koch, D. Weber, M. Lerch y T. Ressler. "Solid-state kinetic investigations of non-isothermal reduction of VO2". Reaction Kinetics, Mechanisms and Catalysis 119, n.º 2 (28 de julio de 2016): 429–44. http://dx.doi.org/10.1007/s11144-016-1055-0.

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15

Korzeniewski, Bernard. "Regulation of oxidative phosphorylation during work transitions results from its kinetic properties". Journal of Applied Physiology 116, n.º 1 (1 de enero de 2014): 83–94. http://dx.doi.org/10.1152/japplphysiol.00759.2013.

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The regulation of oxidative phosphorylation (OXPHOS) during work transitions in skeletal muscle and heart is still not well understood. Different computer models of this process have been developed that are characterized by various kinetic properties. In the present research-polemic theoretical study it is argued that models belonging to one group (Model A), which predict that among OXPHOS complexes complex III keeps almost all of the metabolic control over oxygen consumption (Vo2) and involve a strong complex III activation by inorganic phosphate (Pi), lead to the conclusion that an increase in Pi is the main mechanism responsible for OXPHOS activation (feedback-activation mechanism). Models belonging to another group (Model B), which were developed to take into account an approximately uniform distribution of metabolic control over Vo2 among particular OXPHOS complexes (complex I, complex III, complex IV, ATP synthase, ATP/ADP carrier, phosphate carrier) encountered in experimental studies in isolated mitochondria, predict that all OXPHOS complexes are directly activated in parallel with ATP usage and NADH supply by some external cytosolic factor/mechanism during rest-to-work or low-to-high work transitions in skeletal muscle and heart (“each-step-activation” mechanism). Model B demonstrates that different intensities of each-step activation can account for the very different (slopes of) phenomenological Vo2-ADP relationships observed in various skeletal muscles and heart. Thus they are able to explain the differences in the regulation of OXPHOS during work transitions between skeletal muscle (where moderate changes in ADP take place) and intact heart in vivo (where ADP is essentially constant).

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Doadrio, Antonio L., Antonio Mayorga y Regina Orenga. "VO2+ and Cu2+ Interactions with Ceftriaxone and Ceftizoxime. HPLC Kinetic Studies". Journal of the Brazilian Chemical Society 13, n.º 1 (febrero de 2002): 95–100. http://dx.doi.org/10.1590/s0103-50532002000100015.

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17

Noack, Jens, Nataliya Roznyatovskaya, Jessica Kunzendorf, Maria Skyllas-Kazacos, Chris Menictas y Jens Tübke. "The Influence of Electrochemical Treatment on Electrode Reactions for Vanadium Flow Batteries". ECS Meeting Abstracts MA2022-01, n.º 3 (7 de julio de 2022): 461. http://dx.doi.org/10.1149/ma2022-013461mtgabs.

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The motivation for this work was to obtain an overview of the electrochemical behaviour of vanadium reactions on electrochemically treated glassy carbon electrodes in order to be able to make reproducible statements about changes with the treatment. In addition, optimal conditions for the reactions should be found in order to create a basis for targeted pre-treatment of the electrodes and, if applicable, a possibility for in situ treatments. Furthermore, if possible, causes should be determined by the behavior. A glassy carbon electrode was first polished and then treated in 2 M H2SO4 at different potentials. In a separate measurement setup, linear sweep voltammograms were then recorded instead of cyclic voltammograms in order to change the electrode as little as possible and to calculate kinetic values from the obtained data. In addition, roughness values were determined at selected treatment potentials using confocal microscopy and the surface composition was analyzed using XPS. The reaction rates increased significantly in all reactions compared to polished electrodes and had an optimum treatment potential of approx. 1600 mV vs. Hg/Hg2SO4, although the oxidation reaction of V2+ and the reduction reactions of V3+ and VO2+ had opposite tendencies to oxidation of VO2+ and the reduction of VO2 + in the area of low treatment potentials. In the former, the kinetics increased and in the latter, they decreased. No correlation was found to the roughness or size of the stretched surfaces, although these changed significantly as a result of the treatment. XPS measurements gave indications of a dependence on oxygen functional groups for the different reactions. Figure 1

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Zhang, Heng, Huimei Yu, Zhang Chen, Hongjie Luo y Yanfeng Gao. "Thermal kinetic analysis of metal–insulator transition mechanism in W-doped VO2". Journal of Thermal Analysis and Calorimetry 126, n.º 2 (14 de junio de 2016): 949–57. http://dx.doi.org/10.1007/s10973-016-5579-3.

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Xia, Chuan, Zifeng Lin, Yungang Zhou, Chao Zhao, Hanfeng Liang, Patrick Rozier, Zhiguo Wang y Husam N. Alshareef. "Large Intercalation Pseudocapacitance in 2D VO2(B): Breaking through the Kinetic Barrier". Advanced Materials 30, n.º 40 (30 de agosto de 2018): 1803594. http://dx.doi.org/10.1002/adma.201803594.

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Ben Cheikh, R., A. Guendouz y J. Moravec. "Control of oxidative metabolism in volume-overloaded rat hearts: effects of different lipid substrates". American Journal of Physiology-Heart and Circulatory Physiology 266, n.º 5 (1 de mayo de 1994): H2090—H2097. http://dx.doi.org/10.1152/ajpheart.1994.266.5.h2090.

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The relationship between intracellular energy parameters and myocardial O2 consumption (VO2) was studied in control and volume-overloaded hearts perfused with different lipid substrates and over a range of left ventricular work loads. In control hearts, a unique linear relationship between log of cytosolic [ATP]/[ADPf].[Pi] (where [ADPf] is concentration of free ADP) and myocardial VO2 was observed between low and high work loads for both fatty acids studied. In volume-overloaded hearts perfused in the presence of exogenous palmitate, the slope of the relationship between log [ATP]/[ADPf].[Pi] and myocardial VO2 was considerably depressed. It would seem that, under these conditions, much of the thermodynamic control of respiratory chain function has been lost. When myocardial VO2 was expressed as a function of cytosolic ADPf, the cytosolic ADPf was not regulatory. This may be related to a substrate limitation of the respiratory chain, as suggested by an excessive oxidation of pyridine nucleotides. When octanoate, instead of palmitate, was used, most of the above limitation of the respiration disappeared. With this substrate, the reduction of mitochondrial pyridine nucleotides in volume-overloaded hearts was similar to that in controls, and the linear relationship between log [ATP]/[ADPf].[Pi] and myocardial VO2 reappeared over the range of work loads studied. The above failure of cytosolic phosphate potential and ADPf to drive respiration when mitochondrial NADH is low fits well with the integrated model of kinetic regulation, as proposed by recent nuclear magnetic resonance studies. our results also indicate that, even at high respiratory rates, free-energy change of ATP synthesis of volume-overloaded hearts can be protected by use of an appropriate substrate. This, in turn, prevents contractile failure.

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Kamal, O., T. Eljaddi, El H. El Atmani, I. Touarssi, I. Mourtah, L. Lebrun y M. Hlaïbi. "Process of Facilitated Extraction of Vanadium Ions through Supported Liquid Membranes: Parameters and Mechanism". Advances in Materials Science and Engineering 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/3425419.

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To conduct experiments related to the facilitated extraction phenomenon of vanadium ions (VO2+), three supported liquid membranes (SLMs) were prepared, each containing 0.01 M of methyl cholate (MC), resorcinarene (RESO), or trioctylamine (TOA) as extractive agents. Kinetic and thermodynamic models were developed, based on the interaction of the substrate (VO2+) with the extractive agent T and the diffusion of the formed entity (TS) through the membrane. The experimental results verify the models, and to determine, macroscopic parameters, permeabilities (P) and initial fluxes (J0), and microscopic parameters, association constants (Kass) and apparent diffusion coefficients (D⁎) related to formed entities (TS) and their diffusion through the membrane organic phase. The experimental results indicate that the mechanism on the migration of the VO2+ ions through the membrane organic phase is based on the successive jumps of substrate, from one site to another of the extractive agent. To explain these results and understand the mechanism, we studied influence of temperature factor, and we determined activation parameters (Ea, ΔH≠, and ΔS≠). The results show that this extraction phenomenon is governed by a structural term. Therefore, the membrane performance changes according to nature and structure of the association site presented by each of extractive agents.

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Hon, Jason, Michelle S. Hwang, Meara A. Charnetzki, Issra J. Rashed, Patrick B. Brady, Sarah Quillin y Marvin W. Makinen. "Kinetic characterization of the inhibition of protein tyrosine phosphatase-1B by Vanadyl (VO2+) chelates". JBIC Journal of Biological Inorganic Chemistry 22, n.º 8 (25 de octubre de 2017): 1267–79. http://dx.doi.org/10.1007/s00775-017-1500-1.

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Singh, Sanjay, Hardeo S. Yadav, Ashok Kumar Yadava y Devendra Pratap Rao. "Synthesis of Oxovanadium(IV) Complexes with Tetraaza Coordinating Ligands". Journal of Chemistry 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/947325.

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Oxovanadium(IV) complexes of the type [VO(mac)]SO4(where mac = tetraaza macrocyclic ligands derived by condensation of thenil with 1,4-diaminobenzene or 3,4-diaminopyridine and their reaction withβ-diketones) have been prepared using vanadyl ion as kinetic template. The prepared macrocyclic complexes were characterized by elemental analyses, molar conductance, magnetic moments, and infrared, electronic, and electron spin resonance data. From the spectroscopic studies, five-coordinate square-pyramidal geometry for the VO2+complexes have been proposed wherein derived ligands act as tetradentate chelating agents.

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Song, Bin, Nicolas Aebischer y Chris Orvig. "Reduction of [VO2(ma)2]-and [VO2(ema)2]-by Ascorbic Acid and Glutathione: Kinetic Studies of Pro-Drugs for the Enhancement of Insulin Action†". Inorganic Chemistry 41, n.º 6 (marzo de 2002): 1357–64. http://dx.doi.org/10.1021/ic0111684.

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Toussaint, H. M., A. Beelen, A. Rodenburg, A. J. Sargeant, G. de Groot, A. P. Hollander y G. J. van Ingen Schenau. "Propelling efficiency of front-crawl swimming". Journal of Applied Physiology 65, n.º 6 (1 de diciembre de 1988): 2506–12. http://dx.doi.org/10.1152/jappl.1988.65.6.2506.

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In this study the propelling efficiency (ep) of front-crawl swimming, by use of the arms only, was calculated in four subjects. This is the ratio of the power used to overcome drag (Pd) to the total mechanical power (Po) produced including power wasted in changing the kinetic energy of masses of water (Pk). By the use of an extended version of the system to measure active drag (MAD system), Pd was measured directly. Simultaneous measurement of O2 uptake (VO2) enabled the establishment of the relationship between the rate of the energy expenditure (PVO2) and Po (since when swimming on the MAD system Po = Pd). These individual relationships describing the mechanical efficiency (8-12%) were then used to estimate Po in free swimming from measurements of VO2. Because Pd was directly measured at each velocity studied by use of the MAD system, ep could be calculated according to the equation ep = Pd/(Pd + Pk) = Pd/Po. For the four top class swimmers studied, ep was found to range from 46 to 77%. Total efficiency, defined as the product of mechanical and propelling efficiency, ranged from 5 to 8%.

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Pogliaghi, Silvia, Enrico Tam y Carlo Capelli. "Effect Of Incomplete Recovery On Vo2-on Kinetic During Moderate-intensity Exercise Transitions In Healthy Males." Medicine & Science in Sports & Exercise 46 (mayo de 2014): 524–25. http://dx.doi.org/10.1249/01.mss.0000495039.03877.65.

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García-Alcalde, Laura, Alejandro Concheso, Victoria G. Rocha, Clara Blanco, Ricardo Santamaría y Zoraida González. "Influence of the Oxygen Surface Functionalities Introduced by Electrochemical Treatment on the Behavior of Graphite Felts as Electrodes in VRFBs". Batteries 8, n.º 12 (10 de diciembre de 2022): 281. http://dx.doi.org/10.3390/batteries8120281.

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Graphite felts act as electrodes in VRFBs thanks to their properties such as chemical strength and electrical conductivity or 3D-structure. However, there are significant drawbacks to be overcome, such as their low wettability, sluggish kinetic reversibility and electroactivity towards faradaic processes related to vanadium electroactive species. As a consequence, it is key to alter the fibres to enhance their electrochemical performance during battery operation. Most of the previously reported modifications have been focused on incorporating surface oxygenated functional groups, even though the role of those groups on the electrocatalytic activity towards vanadium faradaic processes is still not clear. Aiming to gain knowledge on this issue, this work investigates the influence of electro-oxidation and electro-reduction treatments, performed in different acidic media (H2SO4 or HNO3 solutions), on their subsequent electrochemical response towards VO2+/VO2+ and V3+/V2+ faradaic processes. The chemical and electrochemical properties of the modified felts were analyzed to understand two key parameters that affect the vanadium reaction catalysis: the depth and oxidation degree of the fibres. A treatment with HNO3, a strong oxidizing agent, leads to a deep oxidation of the fibre and the development of a high density of oxygenated functional groups, mainly C=O, which hinder the redox reactions of vanadium, especially for the faradaic reactions from the catholyte.

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28

Jurowska, Anna, Janusz Szklarzewicz, Maciej Hodorowicz, Wiktoria Serafin, Ennio Zangrando y Ghodrat Mahmoudi. "Ionic Dioxidovanadium(V) Complexes with Schiff-Base Ligands as Potential Insulin-Mimetic Agents—Substituent Effect on Structure and Stability". Molecules 27, n.º 20 (16 de octubre de 2022): 6942. http://dx.doi.org/10.3390/molecules27206942.

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Four dioxidovanadium(V) complexes with Schiff-base ligands based on 2-hydroxybenzhydrazide with four different substituted salicylaldehydes (5-chlorosalicylaldehyde, 3,5-dichlorosalicylaldehyde, 5-nitrosalicylaldehyde, 3-bromo-5-chlorosalicylaldehyde) were synthesized and described, by using V2O5 and triethylamine. The single crystal X-ray structure measurements as well as elemental analyses and IR spectra confirmed the formulas of the ionic complexes with a protonated triethylamine acting as counterion, HTEA[VO2(L)] (HL = Schiff-base ligand). The kinetic stability of the complexes at pH = 2 and 7 was discussed with respect to the neutral vanadium(V) complexes previously studied as potential insulin-mimetic agents. A correlation between the substituents in an aromatic ring of the Schiff-base ligands with crystal packing, and also with the stability of the compounds, was presented.

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29

Gerbino, A., S. A. Ward y B. J. Whipp. "Effects of prior exercise on pulmonary gas-exchange kinetics during high-intensity exercise in humans". Journal of Applied Physiology 80, n.º 1 (1 de enero de 1996): 99–107. http://dx.doi.org/10.1152/jappl.1996.80.1.99.

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The effects of prior exercise on O2 uptake (VO2) kinetics during supra-lactate threshold (LT) cycling were assessed in 11 subjects. Protocols consisted of two consecutive 6-min work bouts separated by 0 W (6 min) with 1) both bouts sub-LT, 2) both bouts supra-LT, 3) bout 1 sub-LT and bout 2 supra-LT, and 4) bout 1 supra-LT and bout 2 sub-LT. Sub-LT VO2 kinetics were similar whether the prior bout was supra- or sub-LT. The VO2 kinetics for supra-LT work preceded by a sub-LT “warm-up” were similar to those for supra-LT work that was not preceded by exercise (O-W warm-up): the “partial”: O2 deficit averaged 2.64 vs. 2.57 liters, and the “effective” VO2 time constant averaged 56 vs. 65 s. Exercise responses (i.e., the change between O W and minute 6 of exercise) were unaffected for lactate concentration (4.58 vs. 4.50 meq/l), pH (-0.08 vs. -0.10), and CO2 output (VCO2; 2.65 vs. 2.49 l/min). However, when the supra-LT work was preceded by a supra-LT warm-up, VO2 kinetics were appreciably faster (O2 deficit = 1.82 liters, VO2 time constant = 37 s) relative to 0-W warm-up; the lactate (0.69 meq/l), pH (-0.01), and VCO2 (2.08 l/min) responses were smaller; and the effective VCO2 time constant was longer (58 vs. 43 s). The mechanism(s) that underlie this speeding of the VO2 kinetics cannot be firmly established, but we suggest that an improved muscle perfusion during the exercise may be involved consequent to the residual metabolic acidemia from the high-intensity warm-up.

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30

Casaburi, R., T. J. Barstow, T. Robinson y K. Wasserman. "Influence of work rate on ventilatory and gas exchange kinetics". Journal of Applied Physiology 67, n.º 2 (1 de agosto de 1989): 547–55. http://dx.doi.org/10.1152/jappl.1989.67.2.547.

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A linear system has the property that the kinetics of response do not depend on the stimulus amplitude. We sought to determine whether the responses of O2 uptake (VO2), CO2 output (VCO2), and ventilation (VE) in the transition between loadless pedaling and higher work rates are linear in this respect. Four healthy subjects performed a total of 158 cycle ergometer tests in which 10 min of exercise followed unloaded pedaling. Each subject performed three to nine tests at each of seven work rates, spaced evenly below the maximum the subject could sustain. VO2, VCO2, and VE were measured breath by breath, and studies at the same work rate were time aligned and averaged. Computerized nonlinear regression techniques were used to fit a single exponential and two more complex expressions to each response time course. End-exercise blood lactate was determined at each work rate. Both VE and VO2 kinetics were markedly slower at work rates associated with sustained blood lactate elevations. A tendency was also detected for VO2 (but not VE) kinetics to be slower as work rate increased for exercise intensities not associated with lactic acidosis (P less than 0.01). VO2 kinetics at high work rates were well characterized by the addition of a slower exponential component to the faster component, which was seen at lower work rates. In contrast, VCO2 kinetics did not slow at the higher exercise intensities; this may be the result of the coincident influence of several sources of CO2 related to lactic acidosis. These findings provide guidance for interpretation of ventilatory and gas exchange kinetics.

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31

Grassi, B., D. C. Poole, R. S. Richardson, D. R. Knight, B. K. Erickson y P. D. Wagner. "Muscle O2 uptake kinetics in humans: implications for metabolic control". Journal of Applied Physiology 80, n.º 3 (1 de marzo de 1996): 988–98. http://dx.doi.org/10.1152/jappl.1996.80.3.988.

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Muscle O2 uptake (VO2) kinetics in response to an augmented energetic requirement (on-transition) has never been directly determined in humans. We have developed a constant-infusion thermodilution technique that allowed rapid measurements of leg blood flow (Qleg) and, in conjunction with frequent serial measurement of arteriovenous O2 content difference across the leg [(Ca - Cv)O2leg], permitted the determination of the VO2 of the leg (VO2leg) at 3- to 4-s time intervals. VO2leg kinetics during the on-transition was taken as a close approximation of muscle VO2 (VO2mus) kinetics. Alveolar VO2 (VO2A), Qleg, leg O2 delivery [(Q.CaO2leg)], (Ca - Cv)O2leg, and VO2leg kinetics were determined in six trained subjects [age 22.8 +/- 4.4 (SD) yr; maximal O2 uptake 59.1 +/- 5.3 ml.kg-1.min-1] during the transition from unloaded pedaling to a workload (loaded pedaling; LP) (183 +/- 20 W) well below the previously determined ventilatory threshold. For all variables, two distinct phases were recognized. During the first 10-15 s of loaded pedaling (phase I), VO2A, Qleg, and (Q.CaO2)leg increased rapidly, whereas VO2leg increased only slightly and (Ca - Cv)O2leg actually decreased. After phase I, all variables showed a monoexponential increase (phase II), with similar time courses [slightly faster for (Ca - CV)O2leg]. In a consideration of both phases, the half times of the responses among variables were not significantly different: 25.5 +/- 2.6 s for VO2A, 26.6 +/- 7.6 s for Qleg, 26.9 +/- 8.3 s for (Q.CaO2leg, 23.5 +/- 1.3 s for (Ca - Cv)O2leg, and 27.9 +/- 5.7 s for VO2leg. We conclude that during the on-transition the kinetics of VO2A and VO2leg, as measured by these methods, are similar. The analysis of the early phase (first 10-15 s) of the on-transition indicates that bulk delivery of O2 to the working muscles is not limiting VO2leg kinetics. However, the present results cannot discriminate between maldistribution of blood flow/VO2 vs. inertia the intracellular oxidative machinery as the limiting factor.

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32

Liu, Hangkai y Qiaowen Yang. "Study on Precipitation Kinetics of Calcium Pyro-Vanadate and Thermodynamics of Vanadium Water System". Metals 13, n.º 1 (20 de diciembre de 2022): 10. http://dx.doi.org/10.3390/met13010010.

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Selective catalytic reduction (SCR) is a technology widely used in large coal-fired units to remove nitrogen oxides from flue gas, but it also generates a large number of waste catalysts every year. At present, the recovery of V from discarded SCR catalysts has good application prospects and environmental significance. In this paper, the kinetics and thermodynamics of vanadium precipitation process are described with the vanadium-containing liquid of waste denitration catalyst recovered by alkali leaching as raw material and CaCl2 as precipitant in order to further explore the mechanism of vanadium precipitation. The kinetics study showed that the crystallization process of calcium pyrovanadate can be well-described by Avrami kinetic model when the precipitation time is 95–130 min, and the vanadium precipitation temperature is 60–80 °C. After that, the Arrhenius equation was used to analyze the fitted kinetic data, and the apparent activation energy Ea of vanadium precipitation reaction was calculated to be 98.196 kJ/mol, and the pre exponential factor A = 8.59 × 1039 min−1. Thermodynamic study showed that when the pH of the vanadium water system is low, the +5 valence vanadium in the solution mainly exists in the form of VO2+ cation. When the pH is between 0–1, the solubility of vanadium reaches the minimum and then increases the solution pH again, and various polymerized anions are formed in the vanadium water system. When the temperature is 25 °C, the activity of vanadium in vanadium-containing solution is 10−1, the pH of solution is 8–12, and the existence form of +5 valence vanadium in solution is mainly HV2O73−. By analyzing the existing forms of V with different activities in a vanadium water system at 25 °C, it can be seen that with the decrease of V activity in liquid, the dominant region of polymerized vanadium-containing species in the potential pH diagram will disappear, indicating that vanadium mainly exists in the form of mononuclear ions in low-concentration vanadium-containing solutions, which is not conducive to precipitation. Therefore, in the process of precipitation of vanadium in solution, the concentration of V should be increased as much as possible.

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33

Wasserman, K. "Coupling of external to cellular respiration during exercise: the wisdom of the body revisited". American Journal of Physiology-Endocrinology and Metabolism 266, n.º 4 (1 de abril de 1994): E519—E539. http://dx.doi.org/10.1152/ajpendo.1994.266.4.e519.

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The changes in cellular respiration needed to increase energy output during exercise are intimately and predictably linked to external respiration through the circulation. This review addresses the mechanisms by which lactate accumulation might influence O2 uptake (VO2) and CO2 output (VCO2) kinetics. Respiratory homeostasis (a steady state with respect to VO2 and VCO2) is achieved by 3-4 min for work rates not associated with an increase in arterial lactate. When blood lactate increases significantly above rest for constant work rate exercise, VO2 characteristically increases past 3 min (slow component) at a rate proportional to the lactate concentration increase. The development of a similar slow component in VCO2 is not evident. The divergence of VCO2 from VO2 increase can be accounted for by extra CO2 release from the cell as HCO3- buffers lactic acid. Thus the slow component of aerobic CO2 production (parallel to VO2) is masked by the increase in buffer VCO2. This CO2, and the consumption of extracellular HCO3- by the lactate-producing cells, shifts the oxyhemoglobin dissociation curve rightward (Bohr effect). The exercise lactic acidosis has been observed to occur after the minimal capillary PO2 is reached. Thus the lactic acidosis serves to facilitate oxyhemoglobin dissociation and O2 transport to the muscle cells without a further decrease in end-capillary PO2. From these observations, it is hypothesized that simultaneously measured dynamic changes in VO2 and VCO2 might be useful to infer the aerobic and anaerobic contributions to exercise bioenergetics for a specific work task.

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34

Wu, Y. D., G. H. Zhang y K. C. Chou. "Preparation of high quality ferrovanadium nitride by carbothermal reduction nitridation process". Journal of Mining and Metallurgy, Section B: Metallurgy 53, n.º 3 (2017): 383–90. http://dx.doi.org/10.2298/jmmb170208025w.

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High quality ferrovanadium nitride was prepared successfully by carbothermal reduction nitridation process by using V2O5 and Fe as the raw materials. The effects of reaction temperature and C/O molar ratio (content of O is defined as the oxygen in V2O5) on the quality of ferrovanadium nitride were investigated in detail. It was demonstrated that C/O molar ratio had a great influence on the residue carbon, as well as the nitrogen content in the final products. It was found that the nitrogen content of the final product achieved 11.52% when the C/O molar ratio was 90% of the stoichiometric value. However, the nitrogen contents of the final products decreased with the further increase of C/O molar ratio. For the temperature higher than 1773 K, Fe became liquid phase and surrounded the solid V(C, N, O) particles tightly. The formation of liquid Fe was beneficial for the further removal of oxygen atoms left in the V(C, N, O) lattice, since it provided a liquid tunnel for carbon diffusion which greatly enhanced the reaction kinetics. From the results of X-ray diffraction (XRD) and thermodynamic calculations, phase evolution sequence of V2O5 can be obtained as: V2O5?VO2?V2O3?V(C, N, O). Moreover, the kinetic process from V2O3 to VN was studied and the results shown that the reaction rate can be described by Jander diffusion model with the extracted activation energy of 188.173 kJ/mol.

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35

Gurd, Brendon J., Donald H. Paterson y John M. Kowalchuk. "Effect Of Prior Heavy-intensity Exercise On The Vo2 On-And Off-kinetic Response To Moderate-intensity Exercise In Young Adults". Medicine & Science in Sports & Exercise 37, Supplement (mayo de 2005): S449. http://dx.doi.org/10.1249/00005768-200505001-02316.

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36

Gurd, Brendon J., Donald H. Paterson y John M. Kowalchuk. "Effect Of Prior Heavy-intensity Exercise On The Vo2 On-And Off-kinetic Response To Moderate-intensity Exercise In Young Adults". Medicine & Science in Sports & Exercise 37, Supplement (mayo de 2005): S449. http://dx.doi.org/10.1097/00005768-200505001-02316.

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37

Yasui, Hiroyuki, Yasuo Kunori y Hiromu Sakurai. "Specific Binding of Vanadyl Ion (VO2+) with Thiolate of the Cysteine-34 Residue in Serum Albumin, Demonstrated by CD Spectroscopy and Kinetic Property". Chemistry Letters 32, n.º 11 (noviembre de 2003): 1032–33. http://dx.doi.org/10.1246/cl.2003.1032.

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38

Parwath, Sheshideep Reddy, Sudhanshu Shekhar Mohapatra y Vineet Kumar Malhotra. "Changes in metabolic gas kinetics on exposure to heat stress". Indian Journal of Aerospace Medicine 66 (21 de octubre de 2022): 9–14. http://dx.doi.org/10.25259/ijasm_15_2022.

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Objectives: Heat stress is one of the major stressors in military aviation with the potential to adversely affect the efficiency of the aircrew and hence flight safety. Metabolic rate (MR) increases on exposure to heat and metabolic gases are considered as a proxy for MR. This study examined the influence of heat stress on metabolic gas kinetics in healthy Indian males and assessed the duration of attaining normal baseline values of metabolic gases post-exposure. Materials and Methods: In 16 healthy male volunteers, cardiorespiratory variables, including metabolic gases (oxygen uptake [VO2], carbon dioxide output [VCO2], minute ventilation [VE], breathing frequency [BF], and heart rate [HR]), were recorded before and approximately 2 h after a standard meal. The subjects were then exposed to a simulated temperature of 40°C with a relative humidity of 70% for 1 h in the environmental chamber. Same physiological parameters were recorded at the end of 30 min and 60 min during heat exposure and up to 90 min following exposure to heat stress at an interval of 30 min. Results: A significant increase (P < 0.001) in mean VO2 (ml/Kg/min) was observed post-meal (1.49 ± 0.95) as well as at 30 min (1.17 ± 0.96) and at 60 min (2.14 ± 1.19) of heat exposure. A similar increase (P < 0.05) in mean VCO2 was observed post-meal and following heat exposure. VE (L/min) increased by 12.12% post-meal (P = 0.01), 16.16% (P < 0.001) at 30 min, and 19.65% (P < 0.001) at 60 min of heat exposure. There was a significant increase in mean BF (per min) during heat exposure (2.31 ± 1.24 at 30 min and 3.53 ± 1.05 at 60 min) and till 60 min of the recovery period compared to baseline (P < 0.001). HR (bpm) increased by 14 bpm at 30 min and 17 bpm at 60 min of exposure and till 30 min after elimination of heat stress (P < 0.001). Conclusion: A statistically significant increase was observed in VO2, VCO2, VE, BF, and HR on exposure to heat stress. Optimal recovery was observed after 30 min of eliminating the heat stress for VO2 and VCO2. Similar recovery was observed after 60 min of eliminating the heat stress for HR and following 90 min for VE and BF. Hence, if the crew is required to continue to operate in the heat stress environment, a minimum period of 90 min of a break in between the sorties must be ensured in a relatively cooler environment.

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39

Barstow, T. J., D. M. Cooper, E. M. Sobel, E. M. Landaw y S. Epstein. "Influence of increased metabolic rate on [13C]bicarbonate washout kinetics". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 259, n.º 1 (1 de julio de 1990): R163—R171. http://dx.doi.org/10.1152/ajpregu.1990.259.1.r163.

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The effect of changes in metabolic rate on the dynamics of CO2 exchange among its various compartments in the human body is not well understood. We examined CO2 dynamics in six healthy male subjects using an intravenous bolus of [13C]bicarbonate. Subjects were studied while resting, during light exercise [50% of the lactate threshold (LT), 3-4 times resting O2 uptake (VO2)], and during moderate exercise (95% of the LT, 6 times resting VO2). The sum of three exponential terms well described the washout of 13CO2 in exhaled breath both at rest and during each exercise level despite substantial increases in metabolic rate accompanying the exercise studies. Average recovery of 13C label rose from 67% during rest to 80% during light and moderate exercise (P less than 0.01). The estimate of CO2 elimination (VCO2) calculated from the washout parameters and corrected for recovery was in very good agreement with the VCO2 directly measured simultaneously breath by breath (r = 0.993, SE for VCO2 = 0.079 l/min). By use of a three-compartment mammillary model, the quantity of CO2 in the central pool (Q1) doubled from rest to light exercise (233 +/- 60 to 479 +/- 76 mmol, P less than 0.01) but did not change further with moderate exercise (458 +/- 74 mmol). Rate constants for exchange between pools and for irreversible loss from the system tended to increase with metabolic rate, but there was large variation in the responses. We conclude that the compartmental dynamics of CO2 transport and storage are very sensitive to changes in metabolic rate induced by exercise.

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40

Buchanan, Cailin y Nirala Singh. "A Kinetic Performance-Informed Technoeconomic Assessment-Life Cycle Assessment Model of Ce and V Redox Flow Batteries". ECS Meeting Abstracts MA2022-01, n.º 3 (7 de julio de 2022): 471. http://dx.doi.org/10.1149/ma2022-013471mtgabs.

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The EIA projects that 60% of cumulative capacity additions in the U.S. by 2050 will be renewable electric generating technologies.1 The use of intermittent renewable energy in the U.S. electricity grid requires energy storage. NREL predicts that for a scenario in which 80% of electricity in the U.S. comes from renewable energy by 2050, 120 GW of energy storage would be needed,2 yet as of 2020, the U.S. has only 24 GW of storage capacity.3 Redox flow batteries (RFBs) are a useful technology for ensuring the smooth integration of renewable energy into the U.S. electricity grid because of their long lifecycles and discharge times. RFBs are currently too expensive for market deployment, however, with the all vanadium RFB (VRFB) costing double the DOE target.4,5 One way to improve the cost effectiveness of RFBs is to explore chemistries that increase the voltage window. The replacement of the VO2+/ VO2 + chemistry at the positive electrode of a VRFB with the Ce3+/Ce4+ chemistry would result in an increased theoretical voltage, but it is unclear how the kinetic, ohmic, and mass transport overvoltages would change. Additionally, studies of the environmental burdens of life cycle phases of Ce RFBs are limited. To advance the most cost effective and least environmentally harmful RFB, in this study, we develop a combined Technoeconomic Assessment-Life Cycle Assessment (TEA-LCA) model that is informed by our performance measurements to compare the levelized cost of electricity (LCOE) and levelized greenhouse gas (LGHG) emissions of VRFBs and Ce-V RFBs. The TEA-LCA model allows the user to select from a list of positive and negative electrode redox chemistries, solvents, electrode materials, and electricity grid generation profiles to calculate the LCOE and LGHG emissions of the battery for the delivery of 1 kWh of energy. A solver function optimizes the current density that minimizes either LCOE or LGHGs. The TEA-LCA model uses a bottom-up approach, in which energy- and power-dependent capital costs and environmental burdens are calculated by converting the amount of material to a kWh basis. Cost estimates are sourced from vendors and GHG emissions are pulled from the GREET database and literature. The amount of active species required to deliver 1 kWh of electricity at a specified discharge time is calculated using the redox couple properties, including redox potential, exchange current density, and limiting currents. These performance parameters are based on measurements collected in lab. The use phase burdens are calculated using the roundtrip efficiency of the battery and the price and GHGs associated with the electricity grid generation mix. End-of-life costs consist of the economic and environmental burdens of recycling and disposing of the battery material and are collected from vendors and GREET. The TEA-LCA model answers important questions related to the optimal operating conditions of an RFB. In addition to comparing the economic and environmental performances of the VRFB and Ce-V RFB, it demonstrates how different electricity grid mixes influence total cost and emissions and highlights the difference in optimal operating current density if cost or GHG emissions are prioritized, e.g., lower current density results in fewer emissions but higher cost in carbon-intensive electricity grid profiles. Preliminary results using literature values show that the Ce-V RFB has an LCOE that is 45% lower than the VRFB LCOE, with capital costs dominating. We will present the finalized LCOE for the VRFB and Ce-V RFB, as well as LGHGs, as a function of discharge time and electricity grid mix. Sensitivity analyses of the input parameters found that for both RFBs, the discount rate, discharge faradaic efficiency, and lifetime of battery had the most influence on LCOE, with a 20% decrease in discharge faradaic efficiency resulting in a 16% increase in LCOE for the VRFB. The results of this TEA-LCA model show that the use of cerium is a viable option for reducing the cost of RFBs to advance their use in renewable energy storage grid applications. Additionally, this model is generalizable to other batteries and electrochemical systems, such as CO2 conversion. Thus, the development of this TEA-LCA model represents not only an advancement to the field of redox flow batteries but also the wider field of electrochemistry. U.S. EIA. Annual Energy Outlook. (2021). Mai, T. et al. Renewable Electricity Futures Study. NREL. (2012). CSS University of Michigan. U. S. Grid Energy Storage Factsheet. (2021). Mongird, K. et al. 2020 Grid Energy Storage Technology Cost and Performance Assessment. (2020). Weber, A. Z. et al. J. Appl. Electrochem. 41, 1137–1164 (2011). Smith, G. F. & Getz, C. A. Ind. Eng. Chem. Res. 10, 191–195 (1938).

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41

Song, Junying, Zhanbin Huang y Fengzhi Yang. "Facile Preparation of Iron-Manganese Oxide@Diatomite Composite for Effective Removal of Vanadium from Wastewater". Australian Journal of Chemistry 72, n.º 9 (2019): 717. http://dx.doi.org/10.1071/ch19164.

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Excess pentavalent vanadium(v) has severely degraded water quality and posed a huge threat to human health over the past several decades. Hence, it’s urgent and significant to explore a novel adsorbent which is low cost and efficient to treat vanadium pollution. In this work, a novel iron-manganese oxide@diatomite (MnFe2O4@DE) adsorbent with superior removal performance for simulated vanadium(v) wastewater was synthesised via a facile hydrothermal method. The as-prepared MnFe2O4@DE composite was characterised through different characterisation techniques. The results indicated that the MnFe2O4 nanoparticles were uniformly deposited on the surface of diatomite, resulting in a larger specific surface area and pore volume of the composite. In addition, the MnFe2O4@DE adsorbent exhibited the highest adsorption capacity for vanadium(v) (18.37mgg−1±0.5%), which was up to around 13.24 and 1.33 times as much as that of pure diatomite and MnFe2O4, respectively. This is mainly attributed to the enhanced specific surface area and pore volume. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis demonstrated vanadium(v) could be reduced to low valence vanadium with low toxicity by the MnFe2O4@DE composite which could exist as VO2+ and VO+ cations in solution. The adsorption process was better fitted with a pseudo-second-order kinetic model and Langmuir model, which is spontaneous and endothermic. Overall, the novel MnFe2O4@DE composite could be applied as a promising adsorbent in addressing vanadium pollution issues due to its properties of low cost, effectiveness, and environmental friendliness.

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42

di Prampero, P. E., P. B. Mahler, D. Giezendanner y P. Cerretelli. "Effects of priming exercise on VO2 kinetics and O2 deficit at the onset of stepping and cycling". Journal of Applied Physiology 66, n.º 5 (1 de mayo de 1989): 2023–31. http://dx.doi.org/10.1152/jappl.1989.66.5.2023.

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Breath-by-breath O2 uptake (VO2) kinetics and increase of blood lactate concentration (delta Lab) were determined at the onset of square-wave stepping (S) or cycling (C) exercise on six male subjects during 1) transition from rest (R) to constant work load, 2) transition from lower to heavier work loads, wherein the baseline VO2 (VO2 s) was randomly chosen between 20 and 65% of the subjects' maximal O2 uptake (VO2 max), and 3) inverse transition from higher to lower work loads and/or to rest. VO2 differences between starting and arriving levels were 20–60% VO2 max. In C, the VO2 on-response became monotonically slower with increasing VO2 s, the half time (t1/2) increasing from approximately 22 s for VO2 s = R to approximately 63 s when VO2 s approximately equal to 50% VO2 max. In S, the fastest VO2 kinetics (t1/2 = 16 s) was attained from VO2 s = 15–30% VO2 max, the t1/2 being approximately 25 s when starting from R or from 50% VO2 max. The slower VO2 kinetics in C were associated with a much larger delta Lab. The VO2 kinetics in recovery were essentially the same in all cases and could be approximated by a double exponential with t1/2 of 21.3 +/- 6 and 93 +/- 45 s for the fast and slow components, respectively. It is concluded that the O2 deficit incurred is the sum of three terms: 1) O2 stores depletion, 2) O2 equivalent of early lactate production, and 3) O2 equivalent of phosphocreatine breakdown.(ABSTRACT TRUNCATED AT 250 WORDS)

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43

Chilibeck, Philip D., Donald H. Paterson, Robert J. Petrella y David A. Cunningham. "The Influence of Age and Cardiorespiratory Fitness on Kinetics of Oxygen Uptake". Canadian Journal of Applied Physiology 21, n.º 3 (1 de junio de 1996): 185–96. http://dx.doi.org/10.1139/h96-015.

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The purpose of this study was to determine the influences of ageing and cardiorespiratory fitness on kinetics of VO2 during the transition to exercise of moderate intensity. Subjects performed three transitions to and from a 6-minute square wave constant load, at an intensity corresponding to 90% of ventilatory threshold (VET), to determine VO2 kinetics. The young group had a significantly faster time constant of VO2 (τVO2). τVO2 was significantly correlated with VO2max for both young and old groups; however, the slope of the τVO2 - VO2max regression equation was steeper for the old group, indicating that fit older subjects had VO2 kinetics that approached those of fit young. A multiple linear regression indicated that relative fitness was the strongest significant predictor of τVO2, followed by sex and age. Although VO2 kinetics are definitely slowed with age, relative levels of cardiorespiratory fitness also have a great influence on the dynamic response of VO2. Key words: VO2max, ventilatory threshold, heart rate kinetics

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44

Gladden, L. B., M. C. Hogan, R. A. Meyer, S. Segal, R. L. Hughson, B. Grassi y B. J. Whipp. "MISCLE VO2 ON-KINETICS". Medicine & Science in Sports & Exercise 31, Supplement (mayo de 1999): S235. http://dx.doi.org/10.1097/00005768-199905001-01113.

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45

McNulty, C. y R. Robergs. "New method for processing and quantifying VO2 kinetics: Linear VO2 onset kinetics". Journal of Science and Medicine in Sport 19 (diciembre de 2015): e49. http://dx.doi.org/10.1016/j.jsams.2015.12.494.

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46

Reis, Victor M., Eduardo B. Neves, Nuno Garrido, Ana Sousa, André L. Carneiro, Carlo Baldari y Tiago Barbosa. "Oxygen Uptake On-Kinetics during Low-Intensity Resistance Exercise: Effect of Exercise Mode and Load". International Journal of Environmental Research and Public Health 16, n.º 14 (15 de julio de 2019): 2524. http://dx.doi.org/10.3390/ijerph16142524.

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Oxygen uptake (VO2) kinetics has been analyzed through mathematical modeling of constant work-rate exercise, however, the exponential nature of the VO2 response in resistance exercise is currently unknown. The present work assessed the VO2 on-kinetics during two different sub maximal intensities in the inclined bench press and in the seated leg extension exercise. Twelve males (age: 27.2 ± 4.3 years, height: 177 ± 5 cm, body mass: 79.0 ± 10.6 kg and estimated body fat: 11.4 ± 4.1%) involved in recreational resistance exercise randomly performed 4-min transitions from rest to 12% and 24% of 1 repetition maximum each, of inclined bench press (45°) and leg extension exercises. During all testing, expired gases were collected breath-by-breath with a portable gas analyzer (K4b2, Cosmed, Italy) and VO2 on-kinetics were identified using a multi-exponential mathematical model. Leg extension exercise exhibited a higher R-square, compared with inclined bench press, but no differences were found in-between exercises for the VO2 kinetics parameters. VO2 on-kinetics seems to be more sensitive to muscle related parameters (upper vs. lower body exercise) and less to small load variations in the resistance exercise. The absence of a true slow component indicates that is possible to calculate low-intensity resistance exercise energy cost based solely on VO2 measurements.

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Poole, David C., Casey A. Kindig, Brad J. Behnke y Andrew M. Jones. "Oxygen uptake (VO2) kinetics in different species: a brief review". Equine and Comparative Exercise Physiology 2, n.º 1 (febrero de 2005): 1–15. http://dx.doi.org/10.1079/ecp200445.

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AbstractWhen a human begins to move or locomote, the energetic demands of its skeletal muscles increase abruptly and the oxygen (O2) transport system responds to deliver increased amounts of O2 to the respiring mitochondria. It is intuitively reasonable that the rapidity with which O2 transport can be increased to and utilized by (VO2) the contracting muscles would be greater in those species with a higher maximal VO2 capacity (i.e., VO2max). This review explores the relationship between VO2max and VO2 dynamics or kinetics at across a range of species selected, in part, for their disparate VO2max capacities. In healthy humans there is compelling evidence that the speed of the VO2 kinetics at the onset of exercise is limited by an oxidative enzyme inertia within the exercising muscles rather than by VO2 delivery to those muscles. This appears true also for the horse and dog but possibly not for a certain species of frog. Whereas there is a significant correlation between VO2max and the speed of VO2 kinetics among different species, it is possible to identify species or individuals within a species that exhibit widely disparate mass-specific VO2max capacities but similar VO2 kinetics (i.e., superlative human athlete and horse).

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48

Vianna, Jeferson M., Francisco Z. Werneck, Emerson F. Coelho, Vinicius O. Damasceno y Victor M. Reis. "Oxygen Uptake and Heart Rate Kinetics after Different Types of Resistance Exercise". Journal of Human Kinetics 42, n.º 1 (1 de octubre de 2014): 235–44. http://dx.doi.org/10.2478/hukin-2014-0077.

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Abstract Oxygen uptake (VO2) and heart rate (HR) kinetics after exercise are important indicators of fitness and cardiovascular health. However, these variables have been little investigated in resistance exercise (RE). The current study compared post-exercise kinetics of VO2 and the HR among different types of REs. The study included 14 males (age: 26.5±5.4 years, body mass: 80.1±11.4 kg, body height: 1.77±0.07 m, fat content: 11.3±4.6%) with RE experience. Dynamic muscle strength was measured using one repetition maximum (1RM) with regard to the half-squat, bench press, pull-down, and triceps pushdown exercises. The participants performed a maximum number of repetitions at 80% of 1RM for each exercise, separated by a recovery period of 60 minutes. VO2 was measured using ergospirometry. VO2 and HR kinetics were assessed using the time constant of the recovery curves, and excess oxygen consumption (EPOC) was calculated afterward. Significant differences were not observed across the exercises with regard to VO2 kinetics. However, the half-squat exercise elicited a greater EPOC than the bench press and triceps pushdown exercises (p<.05). HR kinetics was slower for the half-squat exercise than for the other exercises (p<.05). These findings confirm that the type of RE influences both the cardiac autonomic response post-exercise and EPOC, but not VO2 kinetics

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49

Zacca, Rodrigo, Rui Azevedo, Pedro Figueiredo, João Vilas-Boas, Flávio Castro, David Pyne y Ricardo Fernandes. "VO2FITTING: A Free and Open-Source Software for Modelling Oxygen Uptake Kinetics in Swimming and other Exercise Modalities". Sports 7, n.º 2 (24 de enero de 2019): 31. http://dx.doi.org/10.3390/sports7020031.

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The assessment of oxygen uptake (VO2) kinetics is a valuable non-invasive way to evaluate cardiorespiratory and metabolic response to exercise. The aim of the study was to develop, describe and evaluate an online VO2 fitting tool (VO2FITTING) for dynamically editing, processing, filtering and modelling VO2 responses to exercise. VO2FITTING was developed in Shiny, a web application framework for R language. Validation VO2 datasets with both noisy and non-noisy data were developed and applied to widely-used models (n = 7) for describing different intensity transitions to verify concurrent validity. Subsequently, we then conducted an experiment with age-group swimmers as an example, illustrating how VO2FITTING can be used to model VO2 kinetics. Perfect fits were observed, and parameter estimates perfectly matched the known inputted values for all available models (standard error = 0; p < 0.001). The VO2FITTING is a valid, free and open-source software for characterizing VO2 kinetics in exercise, which was developed to help the research and performance analysis communities.

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50

Barstow, T. J. y P. A. Mole. "Simulation of pulmonary O2 uptake during exercise transients in humans". Journal of Applied Physiology 63, n.º 6 (1 de diciembre de 1987): 2253–61. http://dx.doi.org/10.1152/jappl.1987.63.6.2253.

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Computer simulation of blood flow and O2 consumption (QO2) of leg muscles and of blood flow through other vascular compartments was made to estimate the potential effects of circulatory adjustments to moderate leg exercise on pulmonary O2 uptake (VO2) kinetics in humans. The model revealed a biphasic rise in pulmonary VO2 after the onset of constant-load exercise. The length of the first phase represented a circulatory transit time from the contracting muscles to the lung. The duration and magnitude of rise in VO2 during phase 1 were determined solely by the rate of rise in venous return and by the venous volume separating the muscle from the lung gas exchange sites. The second phase of VO2 represented increased muscle metabolism (QO2) of exercise. With the use of a single-exponential model for muscle QO2 and physiological estimates of other model parameters, phase 2 VO2 could be well described as a first-order exponential whose time constant was within 2 s of that for muscle QO2. The use of unphysiological estimates for certain parameters led to responses for VO2 during phase 2 that were qualitatively different from QO2. It is concluded that 1) the normal response of VO2 in humans to step increases in muscle work contains two components or phases, the first determined by cardiovascular phenomena and the second primarily reflecting muscle metabolism and 2) the kinetics of VO2 during phase 2 can be used to estimate the kinetics of muscle QO2. The simulation results are consistent with previously published profiles of VO2 kinetics for square-wave transients.

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