1,395 research outputs found
The influence of training status, age, and muscle fiber type on cycling efficiency and endurance performance.
Get PDFThe purpose of this study was to assess the influence of age, training status, and muscle fiber-type distribution on cycling efficiency. Forty men were recruited into one of four groups: young and old trained cyclists, and young and old untrained individuals. All participants completed an incremental ramp test to measure their peak O2 uptake, maximal heart rate, and maximal minute power output; a submaximal test of cycling gross efficiency (GE) at a series of absolute and relative work rates; and, in trained participants only, a 1-h cycling time trial. Finally, all participants underwent a muscle biopsy of their right vastus lateralis muscle. At relative work rates, a general linear model found significant main effects of age and training status on GE (P 0.05). Power output in the 1-h performance trial was predicted by average O2 uptake and GE, with standardized ?-coefficients of 0.94 and 0.34, respectively, although some mathematical coupling is evident. These data demonstrate that muscle fiber type does not affect cycling efficiency and was not influenced by the aging process. Cycling efficiency and the percentage of type I muscle fibers were influenced by training status, but only GE at 120 revolutions/min was seen to predict cycling performance
Oscillation in O2 uptake in impulse exercise
Get PDFThe purpose of the present study was to examine 1) whether O2 uptake (VO2) oscillates during light exercise and 2) whether the oscillation is enhanced after impulse exercise. After resting for 1 min on a bicycle seat, subjects performed 5-min pre-exercise with 25 watts work load, 10-s impulse exercise with 200 watts work load and 15-min post exercise with 25 watts work load at 80 rpm. VO2 during pre-exercise significantly increased during impulse exercise and suddenly decreased and re-increased until 23 s after impulse exercise. In the cross correlation between heart rate (HR) and VO2 after impulse exercise, VO2 strongly correlated to HR with a time delay of -4 s. Peak of power spectral density (PSD) in HR appeared at 0.0039 Hz and peak of PSD in VO2 appeared at 0.019 Hz. The peak of the cross power spectrum between VO2 and HR appeared at 0.0078 Hz. The results suggested that there is an oscillation in O2 uptake during light exercise that is associated with the oscillation in O2 consumption in active muscle. The oscillation is enhanced not only by change in O2 consumption but also by O2 content transported from active muscle to the lungs
Fe-polypyrrole/reduced graphene oxide composites for Li-O2 batteries
No full textThe Lithium-Oxygen (Li-O2 or Li-air) batteries have garnered worldwide interest due to its high theoretical values attainable. If successfully developed, it is projected to provide a key role in the electrification of transport. However, due to the high over-potential of the battery, it is still a challenge to use it. Hence, the author proposes the use of Fe-polypyrrole/reduced graphene oxide composites as O2 electrodes for the Li-O2 batteries. The author provides evidence that the use of the reduced graphene oxide results in products that exhibits high round-trip efficiencies and stable cycling performances. The author also discusses his view on the challenges and promises facing the development of the Li-O2 batteries as well as the choices of materials and the current understanding of their chemistry.Bachelor of Engineering (Materials Engineering
Development of CO2-O2 CARS thermometry and concentration measurements for applied flame diagnostics
No full textIn this M.Sc. thesis project a model is developed and validated that simulates the coherent anti-Stokes Raman scattering (CARS) signal of CO2 and O2 in the spectral region between 1250cm-1 and 1680cm-1. The aim is to perform temperature and concentration measurements in a typical hydrocarbon-air combustion flame. The project makes use of a two-beam time resolved CARS setup, with ultraboadband generated light from the pump/Stokes beam to excite the Raman transitions in this spectral window. In the 1250-1680cm-1 region, CARS signatures of both CO2 and O2 are visible making it possible to perform thermometry on both molecular species, while also offering the option of evaluating relative CO2-O2/O2-CO2 concentrations. The appearance of the oxygen ro-vibrational (O-, S- and Q-branch) spectrum at low temperatures, along with a strong manifestation of the CO2 Fermi influenced Q-branch (with red-shifted peaks below 1300cm-1 and blue shifted peaks above 1350cm-1) at higher temperatures, makes it possible to perform thermometry in low and high temperature combustion environments on both the reactant and product side. A total of 256 vibrational levels for CO2 are taken into account for the model to simulate the CO2 Fermi polyad. From these 256 vibrational levels, 181 Raman transitions are possible that fulfill the criteria of Δv1=1, Δv2=0, Δv3=0, Δl=0 and ΔJ=0 . Three different experiments are performed including an M-flame, a V-flame and two experiments conducted in air for model validation. The temperature analysis using CO2 provided satisfactory results regarding temperature assessments. Depending on the experiment, standard deviations below 2.3% and mean temperatures to within 1% of the temperatures corresponding to the expected values. The O2 analysis showed a good correspondence to the CO2 temperature values, differing by 43-76K. The O2 analysis showed low standard deviations for the air temperature assessment (3.27%) and reliably predicted the ambient temperature with a difference lower than 2K. The M-flame experiments showed the least correspondence to actual values. These unsatisfactory results can for one part be attributed to the high signal-to-noise ratios (SNR) and for one part due to the flickering of the flame. In terms of concentration assessment the model closely evaluates O2-CO2 concentrations in the ambient air and from an exhaled human breath, while the flame assessments had a mediocre correspondence to the predicted ones from \textit{chem1d}. All in all the project shows that CO2 temperature and concentration measurements in this CARS spectral region is feasible. It offers promise from a combustion perspective due to the possibility of performing simultaneous (O2) rotational and (CO2/O2) vibrational thermometry, which makes it possible to perform measurements on both the product and reactant side of the flame front, while including spectral signatures of possibly three major molecular combustion species: CO2, O2 and H2. Further improvements to the model and the application of the technique, make more complex combustion studies possible and help achieve the goal to develop a ultrafast, multiplex, state-of-the-art laser diagnostic tool for gas phase combustion measurements.Aerospace Engineerin
Symbiosis extended: exchange of photosynthetic O2 and fungal-respired CO2 mutually power metabolism of lichen symbionts
No full textLichens are a symbiosis between a fungus and one or more photosynthetic microorganisms that enables the symbionts to thrive in places and conditions they could not compete independently. Exchanges of water and sugars between the symbionts are the established mechanisms that support lichen symbiosis. Herein, we present a new linkage between algal photosynthesis and fungal respiration in lichen Flavoparmelia caperata that extends the physiological nature of symbiotic co-dependent metabolisms, mutually boosting energy conversion rates in both symbionts. Measurements of electron transport by oximetry show that photosynthetic O2 is consumed internally by fungal respiration. At low light intensity, very low levels of O2 are released, while photosynthetic electron transport from water oxidation is normal as shown by intrinsic chlorophyll variable fluorescence yield (period-4 oscillations in flash-induced Fv/Fm). The rate of algal O2 production increases following consecutive series of illumination periods, at low and with limited saturation at high light intensities, in contrast to light saturation in free-living algae. We attribute this effect to arise from the availability of more CO2 produced by fungal respiration of photosynthetically generated sugars. We conclude that the lichen symbionts are metabolically coupled by energy conversion through exchange of terminal electron donors and acceptors used in both photosynthesis and fungal respiration. Algal sugars and O2 are consumed by the fungal symbiont, while fungal delivered CO2 is consumed by the alga.Water Resource
An Ir/WO3 catalyst for selective reduction of NO with CO in the presence of O2 and/or SO2
Get PDFThe catalytic performance of Ir/WO3 catalyst has been studied in the reduction of NO with CO in the presence of O2 and/or SO2. The catalyst was active for the selective reduction of NO to N2 without foreign gases. The conversion of NO to N2 was further enhanced by the addition of a small amount of O2 while that to N2O was reduced. The N2 conversion went through a maximum, which depended on the composition of the reacting gaseous mixture (NO and CO). The catalyst was still active at higher O2 concentrations up to 5%, so this Ir/WO3 catalyst can be used effectively under lean-burn conditions. The presence of SO2 (100 ppm) caused a significant deactivation but this negative effect was completely removed by co-existing O2. The reaction mechanisms and the effects of co-existing O2 and SO2 gases are discussed on the bases of those reaction results, those of the reduction of NO2 instead of NO, and FTIR measurements of the catalysts after the reactions under various conditions. Possible reaction pathways are proposed, which depend on the concentration of O2 added in the reaction mixture
Luminescent center in Br--rich BaFBr : O2-
No full textIn this work, emission, excitation and absorption spectra of pure and 1 mol% O2- -doped BaFxBr2 -x (x = 0.98, 1.0, 1.02) powders were measured. It was found that the spectra of O2- -doped Br--rich sample (x = 0.98) is different from those of the other O2--doped samples (x = 1.0 and 1.02). Its emission peak shifts from 500 to 550 nm, and becomes much wider. Absorption spectra show that F(Br-) centers of the X-rayed Br--rich sample, unlike those of other X-rayed samples, are not disturbed by doped oxygen. With the EPR, it is shown that O2- ions are on the F- sites in either F--rich(x = 1.02) or Br--rich sample. We suggested that in the Br--rich sample (x = 0.98) the luminescence is due to an O-F '-V-F(.) pair, instead of the O-F'-V-Br(.) pair in other samples (x = 1.0 and 1.02). (C) 1999 Elsevier Science B.V. All rights reserved.OpticsSCI(E)EI2ARTICLE3231-2358
Calibration and analysis of the telluric O2-bands: A spectropolarimetric approach for aerosol and cloud analysis
No full textEarthshine observations are a classical benchmark for the studies of the atmospheres of exo-earth type planets. For this kind of observations, background subtraction is a critical and challenging task to disentangle the effects of atmospheric scattering from atmospheric transmission of molecular lines. In fact, although usually neglected, the background itself carries information on the composition of our atmosphere, and further crucial information may be extracted from the analysis of spectropolarimetric observations of the O2 lines at sunset. In this talk we will first discuss the surprisingly high variability of telluric lines in Earthshine spectra. With full vector radiative transfer calculations of the Earth\u2019s atmosphere we show the impact of aerosol and cloud properties on the spectropolarimetric appearance of the O2 band. They demonstrate that high spectral resolution observations allow to constrain high clouds and aerosols with high sensitivity. We suggest to use HARPS in polarimetric mode to observe the sky at zenith during sunset various times in order to obtain a larger sample of different sky polarisation spectra at high resolution in the O2B spectral band for further modelling
gwastro/o2-bbh-pe: v2.1 data release of O2 Binary Black Hole posterior samples
No full text<p>This is the v2.1 data release associated with the parameter estimation analysis of the binary black-hole signals from Advanced LIGO-Virgo's second observing run, using the PyCBC Inference toolkit : <a href="https://iopscience.iop.org/article/10.1088/1538-3873/aaef0b">https://iopscience.iop.org/article/10.1088/1538-3873/aaef0b</a> . A companion paper presenting our parameter estimation analysis and the data release is available here : <a href="https://arxiv.org/pdf/1811.09232.pdf">https://arxiv.org/pdf/1811.09232.pdf</a>.</p>
<p>The analysis was performed using the PyCBC v1.12.3 code on the gravitational-wave data available at <a href="https://www.gw-openscience.org/catalog/GWTC-1-confident/html/">https://www.gw-openscience.org/catalog/GWTC-1-confident/html/</a> . Descriptions of the gravitational-wave data can be found in the paper <a href="https://arxiv.org/abs/1811.12907">https://arxiv.org/abs/1811.12907</a> .</p>
<p>The change in this release is an update to the title of the work, and the author list. The data and configuration files included remain the same as in the v2.0 release.</p>
<p>This release includes :</p>
<ul>
<li>posterior and prior samples from parameter estimation analyses of the seven binary black-hole events---GW170104, GW170608, GW170729, GW170809, GW170814, GW170818, and GW170823.</li>
<li>PSDs used in each of the analyses</li>
<li>configuration files and run scripts for running the analyses and generating the data.</li>
<li>tutorials for manipulating the data and reconstructing the figures in the companion paper.</li>
</ul>
The effects of various pesticides and an herbicide on the O2 uptake of soil microbes, 1967
Get PDFA study was made of the influence of 3 pesticides and an herbicide on the O2 uptake of soil microbes. The chemicals included DDT, Dieldin, Malathion, and 2, 4-D/2, 4, 5-T. Dosage rates were chosen to approximate the maximum amount used in field practice. The rate of oxygen uptake by the soil, using conventional manometric procedures, was taken as a criterion of the biological activity of the soil. At the recommended concentration the pesticides and herbicide exerted no measurable effect on the O2 uptake of the soil microbes. In order to test if higher concentrations have an effect, the concentrations were increased to 10 and 100 times the recommended field concentrations. A significant decrease in oxygen uptake was observed only at 100 times the recommended field concentration. It was concluded in light of these observations that high dosages exceeding the recommended concentrations are necessary to evoke a significant effect on 02 uptake of soil microbes
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