The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Guy Plasqui - One of the best experts on this subject based on the ideXlab platform.
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Classical experiments in whole-body metabolism: open-circuit respirometry—diluted flow chamber, hood, or facemask systems
European Journal of Applied Physiology, 2018Co-Authors: Paul F. Schoffelen, Guy PlasquiAbstract:For over two centuries, scientists have measured gas exchange in animals and humans and linked this to energy expenditure of the body. The aim of this review is to provide a comprehensive overview of open-circuit diluted flow indirect calorimetry and to help researchers to make the optimal choice for a certain system and its application. A historical perspective shows that ‘open circuit diluted flow’ is a technique first used in the 19th century and applicable today for room Calorimeters, ventilated hood systems, and facemasks. Room Calorimeters are a classic example of an open-circuit diluted flow system. The broadly applied ventilated hood Calorimeters follow the same principle and can be classified as a derivative of these room Calorimeters. The basic principle is that the subject breathes freely in a passing airflow that is fully captured and analyzed. Oxygen and CO_2 concentrations are measured in inlet ambient air and captured outlet air. The airflow, which is adapted depending on the application (e.g., rest versus exercise), is measured. For a room indirect calorimeter, the dilution in the large room volume is also taken into account, and this is the most complex application of this type of calorimeter. Validity of the systems can be tested by alcohol burns, gas infusions and by performing repeated measurements on subjects. Using the latter, the smallest CV (%) was found for repeated V O_2max tests (1.2%) with an SD of approximately 1 kJ min^−1. The smallest SD was found for sleeping metabolic rate (0.11 kJ min^−1) with a CV (%) of 2.4%.
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classical experiments in whole body metabolism open circuit respirometry diluted flow chamber hood or facemask systems
European Journal of Applied Physiology, 2018Co-Authors: Paul F. Schoffelen, Guy PlasquiAbstract:For over two centuries, scientists have measured gas exchange in animals and humans and linked this to energy expenditure of the body. The aim of this review is to provide a comprehensive overview of open-circuit diluted flow indirect calorimetry and to help researchers to make the optimal choice for a certain system and its application. A historical perspective shows that ‘open circuit diluted flow’ is a technique first used in the 19th century and applicable today for room Calorimeters, ventilated hood systems, and facemasks. Room Calorimeters are a classic example of an open-circuit diluted flow system. The broadly applied ventilated hood Calorimeters follow the same principle and can be classified as a derivative of these room Calorimeters. The basic principle is that the subject breathes freely in a passing airflow that is fully captured and analyzed. Oxygen and CO2 concentrations are measured in inlet ambient air and captured outlet air. The airflow, which is adapted depending on the application (e.g., rest versus exercise), is measured. For a room indirect calorimeter, the dilution in the large room volume is also taken into account, and this is the most complex application of this type of calorimeter. Validity of the systems can be tested by alcohol burns, gas infusions and by performing repeated measurements on subjects. Using the latter, the smallest CV (%) was found for repeated VO2max tests (1.2%) with an SD of approximately 1 kJ min−1. The smallest SD was found for sleeping metabolic rate (0.11 kJ min−1) with a CV (%) of 2.4%.
J.y. Monteau - One of the best experts on this subject based on the ideXlab platform.
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High pressure calorimetry. Comparison of two systems (differential vs.single cell). Application of the phase change of water under pressure
Journal of Thermal Analysis and Calorimetry, 2001Co-Authors: Alain Le Bail, D. Chevalier, J.m. Chourot, J.y. MonteauAbstract:In high pressure calorimetry, pressure change is used to obtain the desired phenomenon (i.e. phase change) at constant temperature. Two high pressure Calorimeters have been developed to measure the latent heat of fusion of pure water (hexagonal ice-type I) at subzero temperature. Both Calorimeters used a constant pressurization rate produced with a high pressure pump driven by a step motor. The first calorimeter was a single cell calorimeter where mercury acted as the pressurization fluid, while the second one was differential (two cells) and was pressurized with pentane. Both Calorimeters gave high accuracy data of latent heat fusion of pure water, which were determined taking into account that either the fluid used to pressurize or the pressurization rate affected the calorimetric signal.
Paul F. Schoffelen - One of the best experts on this subject based on the ideXlab platform.
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Classical experiments in whole-body metabolism: open-circuit respirometry—diluted flow chamber, hood, or facemask systems
European Journal of Applied Physiology, 2018Co-Authors: Paul F. Schoffelen, Guy PlasquiAbstract:For over two centuries, scientists have measured gas exchange in animals and humans and linked this to energy expenditure of the body. The aim of this review is to provide a comprehensive overview of open-circuit diluted flow indirect calorimetry and to help researchers to make the optimal choice for a certain system and its application. A historical perspective shows that ‘open circuit diluted flow’ is a technique first used in the 19th century and applicable today for room Calorimeters, ventilated hood systems, and facemasks. Room Calorimeters are a classic example of an open-circuit diluted flow system. The broadly applied ventilated hood Calorimeters follow the same principle and can be classified as a derivative of these room Calorimeters. The basic principle is that the subject breathes freely in a passing airflow that is fully captured and analyzed. Oxygen and CO_2 concentrations are measured in inlet ambient air and captured outlet air. The airflow, which is adapted depending on the application (e.g., rest versus exercise), is measured. For a room indirect calorimeter, the dilution in the large room volume is also taken into account, and this is the most complex application of this type of calorimeter. Validity of the systems can be tested by alcohol burns, gas infusions and by performing repeated measurements on subjects. Using the latter, the smallest CV (%) was found for repeated V O_2max tests (1.2%) with an SD of approximately 1 kJ min^−1. The smallest SD was found for sleeping metabolic rate (0.11 kJ min^−1) with a CV (%) of 2.4%.
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classical experiments in whole body metabolism open circuit respirometry diluted flow chamber hood or facemask systems
European Journal of Applied Physiology, 2018Co-Authors: Paul F. Schoffelen, Guy PlasquiAbstract:For over two centuries, scientists have measured gas exchange in animals and humans and linked this to energy expenditure of the body. The aim of this review is to provide a comprehensive overview of open-circuit diluted flow indirect calorimetry and to help researchers to make the optimal choice for a certain system and its application. A historical perspective shows that ‘open circuit diluted flow’ is a technique first used in the 19th century and applicable today for room Calorimeters, ventilated hood systems, and facemasks. Room Calorimeters are a classic example of an open-circuit diluted flow system. The broadly applied ventilated hood Calorimeters follow the same principle and can be classified as a derivative of these room Calorimeters. The basic principle is that the subject breathes freely in a passing airflow that is fully captured and analyzed. Oxygen and CO2 concentrations are measured in inlet ambient air and captured outlet air. The airflow, which is adapted depending on the application (e.g., rest versus exercise), is measured. For a room indirect calorimeter, the dilution in the large room volume is also taken into account, and this is the most complex application of this type of calorimeter. Validity of the systems can be tested by alcohol burns, gas infusions and by performing repeated measurements on subjects. Using the latter, the smallest CV (%) was found for repeated VO2max tests (1.2%) with an SD of approximately 1 kJ min−1. The smallest SD was found for sleeping metabolic rate (0.11 kJ min−1) with a CV (%) of 2.4%.
Alain Le Bail - One of the best experts on this subject based on the ideXlab platform.
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High pressure calorimetry. Comparison of two systems (differential vs.single cell). Application of the phase change of water under pressure
Journal of Thermal Analysis and Calorimetry, 2001Co-Authors: Alain Le Bail, D. Chevalier, J.m. Chourot, J.y. MonteauAbstract:In high pressure calorimetry, pressure change is used to obtain the desired phenomenon (i.e. phase change) at constant temperature. Two high pressure Calorimeters have been developed to measure the latent heat of fusion of pure water (hexagonal ice-type I) at subzero temperature. Both Calorimeters used a constant pressurization rate produced with a high pressure pump driven by a step motor. The first calorimeter was a single cell calorimeter where mercury acted as the pressurization fluid, while the second one was differential (two cells) and was pressurized with pentane. Both Calorimeters gave high accuracy data of latent heat fusion of pure water, which were determined taking into account that either the fluid used to pressurize or the pressurization rate affected the calorimetric signal.
Steven M. Jones - One of the best experts on this subject based on the ideXlab platform.
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Closed Gap Slug Calorimeter for Plasma Stream Characterization
2012Co-Authors: Anuscheh Nawaz, Sergey Gorbunov, Imelda Terrazas-salinas, Steven M. JonesAbstract:Slug Calorimeters are used in sheer and stagnation mode to characterize heat flux levels for high enthalpy streams. The traditional design features a gap between slug and holder, which can be of concern in these convective heat flux environments. The challenge is to develop a calorimeter that closes the gap to gas flow, but largely maintains thermal insulation of the slug. The work presented herein introduces two new slug calorimeter designs featuring a closed gap. This is done using either aerogel as a filler or press fitting the slug with a disk. The designs were verified and compared to the baseline calorimeter design under radiative heat flux. Building on this, the Calorimeters were exposed to convective heat flux in the arc-jet facilities. Results from the new designs and conclusions on the impact of the gap in convective heat flux will be shown.
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investigation of slug calorimeter gap influence for plasma stream characterization
43rd AIAA Thermophysics Conference, 2012Co-Authors: Anuscheh Nawaz, Imelda Terrazassalinas, Sergey Gorbunov, Steven M. JonesAbstract:Slug Calorimeters are currently used in shear and stagnation mode to measure heat flux levels, and characterize plasma stream enthalpy. The traditional design features a gap between slug and holder, to thermally insulate the slug from the holder and to allow the use of the one dimensional heat flux assumption. It is suggested that the plasma in this gap could cause some error in the heat flux measurement. In order to investigate this hypothesis, three calorimeter designs with closed gaps were developed and compared to the standard calorimeter design. One design uses aerogel as filler, the other two use copper or constantan rings, press fitted against the slug on a knife edge surface. The designs were verified against the baseline calorimeter design under radiative heat flux. The Calorimeters were then exposed to convective heat flux in the arc-jet facilities. The influence of the gap on stagnation heat fluxes measured is shown and discussed in the present work. It was found, that the heat fluxes measured in the arc jet with all four calorimeter designs compared within 3.5%, after correcting for thermal losses. This indicates that the gap does not play a major role for stagnation heat flux measurement.
