Showing papers on "Calorimeter published in 1984"
TL;DR: The method is of particular value in assessing the rapid changes in metabolic rate which occur as a result of changes in activity, nutritional state, environmental temperature and the administration of drugs.
Abstract: A method is described for determining rapid changes in gaseous exchange between a subject and the environment, while living in a whole body opencircuit calorimeter. The formulae which must be applied to standard estimates of oxygen consumption are derived the computation of rates of change of gas concentration is discussed the sensitivity of estimated heat production to errors in gas concentration is determined and heat production shown to be largely independent of CO2 measurements; and examples of veritication of the method for known rates of gas injection, and of its use with human subjects, are given. The method is of particular value in assessing the rapid changes in metabolic rate which occur as a result of changes in activity, nutritional state, environmental temperature and the administration of drugs. Such changes are monitored in an unrestrained subject living in a whole-body calorimeter rather than in a subject living with the restrictions imposed by a face-mask or ventilated hood.
112 citations
TL;DR: In this paper, the temperature rise following absorption of a single photon was measured using a non-dispersive spectroscopic x-ray detector, and the measured resolution of 270eV full width at half maximum (FWHM) and the absolute amplitude of the response were consistent with predictions.
Abstract: Tests have been made of a nondispersive spectroscopic x‐ray detector which operates by measuring the temperature rise following absorption of a single photon. We have observed thermal pulses from 6‐keV x‐rays, and have resolved the different amplitudes resulting from Mn Kα and K β events. This device was assembled to make quantitative tests of theoretical calculations of the properties of such detectors, and its high heat capacity does not allow it to attain the very high resolution predicted for detectors made by more sophisticated, but still straightforward, techniques. Both the measured resolution of 270‐eV full width at half maximum (FWHM) and the absolute amplitude of the response are consistent with predictions. Nonthermal effects in the thermistor limit the precision of this comparison to about 30%.
91 citations
TL;DR: In this article, a new heat-flow and liquid-flow calorimeter utilizing a Calvet microcalorimeter is described; it can be used to measure excess enthalpies of liquids at temperatures and pressures up to 700 K and 50 MPa.
85 citations
TL;DR: In this paper, an automated Tian-Calvet heat-flow calorimeter operating under digital control was described, which was calibrated in the range 85 to 290 K using synthetic sapphire.
84 citations
TL;DR: A small-volume titration calorimeter of high sensitivity has been developed for the purpose of studying biochemical reactions where the amounts of material are limited to a few nanomoles.
62 citations
TL;DR: In this article, an isothermal flow calorimeter suitable for measuring either endothermic or exothermic heats of mixing from 373 to 673 K and from 0.1 to 40.5 MPa is described.
45 citations
TL;DR: In this paper, a quasi-isothermal graphite graphite calorimeter is described, which is characterized by a power-compensating measuring principle, and compared with the quasi-adiabatic method of operation.
Abstract: A quasi-isothermal method of operating an absorbed-dose graphite calorimeter is described in theory and practice. In contrast with the well-known quasi-adiabatic operation, which entails temperature increases during measurements, in the quasi-isothermal mode the temperatures of the different graphite bodies remain constant except for small temperature drifts throughout the measurement. This implies that the temperature dependence of the specific heat of the absorber and of the sensitivity of the temperature sensor influence the absorbed-dose determination significantly less. The method is characterized by a power-compensating measuring principle which is illustrated with a 3-body graphite calorimeter. Comparisons of the quasi-isothermal with the quasi-adiabatic method of operation showed good agreement.
33 citations
TL;DR: In this paper, a flow calorimeter of the heat conduction type is described, which is capable of measuring the heat effect associated with the process of dissolving slightly soluble gases into water.
Abstract: A flow calorimeter of the heat conduction type is described, which is capable of measuring the heat effect associated with the process of dissolving slightly soluble gases into water. The calorimeter operates in a steady‐state mode. Gas, fed at constant rate, is dissolved in flowing water within a specially designed microcalorimeter cell and the power is determined for the process. Computer control of the gas flow is used for convenient establishment of steady states. The calorimeter is calibrated electrically with a precision of 0.2% for power levels of 150–450 μW. Reproducibility of successive measurements of heats of solution of oxygen are within 1%. Results are presented for the enthalpy change for the dissolution of oxygen gas into pure water at 25 °C.
33 citations
TL;DR: A small calorimeter is constructed with which to measure the temperature rise in irradiated water saturated with various gases, and results are consistent with model calculations, except for some differences for accumulated doses of less than 100 Gy.
Abstract: Recent measurements of the absorbed dose to air-saturated water, made using water calorimetry and assuming a zero heat defect for irradiated water, gave results 2%-5% higher than those determined by more conventional means. According to the current radiation chemical model for air-saturated water, the dose measured by water calorimetry assuming a zero heat defect should actually be 2% too low because of the endothermicity of the radiolysis processes in water. In order to examine possible sources for this discrepancy, we have constructed a small calorimeter (holding 100 ml of water) with which to measure the temperature rise in irradiated water saturated with various gases. The gases used were air, oxygen, argon, nitrogen, and hydrogen/oxygen mixtures. Irradiations were carried out with 20-MV x rays at a dose rate of 0.41 Gy/s. Our results are consistent with model calculations, except for some differences for accumulated doses of less than 100 Gy. The discrepancies we find at low doses and the discrepancies observed by others using water calorimeters may arise from impurities in the water.
30 citations
01 Jan 1984
TL;DR: In this article, a heat release rate calorimeter devexoped at the National Bureau of Standards was used to measure the fire performance of a wide range of furnishings.
Abstract: A 200-word or less factual summary of most significant information. If document includes a significant bibliography or literature survey, mention it here) A heat release rate calorimeter devexoped at the National Bureau of Standards was used to measure the fire performance of a wide range of furnishings. The heat release rates measured in the calorimeter are determined through the use of oxygen consumption techniques. Data are presented on the free burning characteristics of 28 tests involving 23 different types of furnishings. The furnishings evaluated are classed into the following groups: easy chairs, sofas, waiting room and patient chairs, wardrobe closets, bookcase and bedding. The information presented in this report will provide a basis for selecting types of furniture to be used in health care facilities, hospitals and other living facilities. The test results also provide information needed by other areas of fire research, such as the study of fire growth in compartments and mathematical modeling of fire development. In addition to heat release rates, data are given on the rates of mass loss, thermal radiation and smoke production from the burning furniture specimens. 12.
29 citations
CERN1
TL;DR: In this article, a small calorimeter element made of planes of 0.9 mm diameter fibres alternating with Pb plates has been built and tested in an electron beam, achieving an energy resolution of σE/√E⋍9.8 and 7.8% respectively.
TL;DR: In this paper, a simple isoperibol heat-flow calorimeter operating at temperatures up to 1300 K has been built, which allows detection of enthalpy changes of 0.05 J, and is suitable for precise measurement of 8 J or more.
Patent•
10 Dec 1984
TL;DR: In this article, a Peltier effect thermoelectric cooler is used to remove heat from the heat sink of a catalytic calorimeter, and an output device records the amount of heat supplied to the catalyst and the amount that was removed from a heat sink.
Abstract: A catalytic calorimeter measures the heat value of a gas and includes a chamber for receiving gas and air. A catalyst within the chamber causes the combustion of the gas and air, while a first thermocouple provides a signal indicating the temperature of the gas and air prior to combustion. A second thermocouple indicates the temperature of the catalyst, which is heated by an electrical resistance heater. A first temperature controller is connected to the second thermocouple and the heater for maintaining the catalyst at a predetermined temperature. A heat sink within the chamber absorbs heat from the products of the combustion of the gas and a third thermocouple indicates the temperature of the heat sink. A Peltier effect thermoelectric cooler is provided to remove heat from the heat sink. A second temperature controller connected to the third thermocouple and the cooler maintains the heat sink at a predetermined temperature. An output device records the amount of heat supplied to the catalyst and the amount of heat removed from the heat sink.
TL;DR: In this paper, a low-temperature adiabatic microcalorimeter for heat capacity determination was developed, consisting of a sample cell and a thermometric copper block.
Abstract: A low-temperature adiabatic microcalorimeter for heat capacity determination was developed. The calorimeter is of the twin type, consisting of a sample cell and thermometric copper block. The temperature of the cell is transferred to the block by a fine thermocouple and a controlling system, and the temperature of the block is measured by standard thermometry. This reduces heat transfer through thermometer leads and thus avoids self-heating due to thermometric current. Heat capacities of two sample cells, one is 0.6 cm3 and the other 1.2 cm3 in the internal volumes, were measured in the temperature range between 13 and 300K with discontinuous heating mode. Accuracy of the calorimeter was tested by a US calorimetry conference standard benzoic acid crystal. The estimated inaccuracy is 1% at 20K, 0.1% at 70K and 0.3% above 170K.
TL;DR: In this article, the shape memory effect associated with a thermoelastic martensitic transformation can be used to convert heat directly into mechanical work, and the amount of heat necessary to carry the engines through a cycle was estimated from calorimeter measurements and the work performed per cycle.
Abstract: The mechanical shape memory effect associated with a thermoelastic martensitic transformation can be used to convert heat directly into mechanical work. Laboratory simulation of two types of heat engine cycles (Stirling and Ericsson) has been performed to measure the amount of work available per cycle in a Ni-45 at% Ti alloy. Tensile deformations at ambient temperature induced martensite, while a subsequent increase in temperature, caused a reversion to the parent phase during which a load was carried through the strain recovery, i.e. work was accomplished. The amount of heat necessary to carry the engines through a cycle was estimated from calorimeter measurements and the work performed per cycle. The measured efficiency of the system tested reached a maximum of 1.4% which was well below the theoretical (Carnot) maximum efficiency of 35.6%.
TL;DR: In this paper, enthalpies of fusion for H218O and tetrahydrofuran clathrate hydrate THF•16.9H218O have been determined using a heat flow calorimeter.
Abstract: Heat capacities between 100 and 270 K and enthalpies of fusion for H218O and tetrahydrofuran clathrate hydrate THF•16.9H218O have been determined using a heat flow calorimeter. The results are compared with the corresponding systems containing H216O. The isotope effects on heat capacities, enthalpies of fusion, and temperature of fusion have been used to calculate 18O fractionation factors, a, for the solid–liquid equilibrium in water and the hydrate. For H218O, α = 1.0032 ± 0.0007 at 273.2 K and for THF•16.9H218O, α = 1.0037 ± 0.0006 at 277.3 K.
TL;DR: In this article, a new cell for the use in immersion calorimetry using the Calvet calorimeter (Setaram MS70) is described and tested, and corrections for the energies of bulb breaking and evaporation of liquid can be made to about ± 1 mJ.
TL;DR: In this article, the authors measured the molar heat capacities of pure C 6 H 13 OH and { x C 6H 13 OH+(1− x )C 6 H 14 } in an adiabatic calorimeter over the whole range of x at temperatures from 230 to 300 K.
TL;DR: In this paper, a general procedure for sequential identification of the parameters of a reaction calorimeter is proposed and a recursive on-line estimation of the heat capacity is performed using a microprocessor.
TL;DR: The Tian-Calvet calorimeter as discussed by the authors was designed for isothermal operation between 298.15 and 1273 K, with a maximum sample capacity of 30 to 40 cm3 in each of the twin reaction zones.
15 Nov 1984-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the performances of a liquid argon calorimeter with wide gaps (2.8 cm) operating in current sensitive mode have been studied with 6.6-36 GeV electron and 40 GeV pion beams at the IHEP accelerator.
Abstract: The performances of a liquid argon calorimeter with wide gaps (2.8 cm) operating in current sensitive mode have been studied with 6.6–36 GeV electron and 40 GeV pion beams at the IHEP accelerator. The good uniformity in charge collection efficiency obtained with this unusual mode has led to a reduction of sampling fluctuations to values of σ S E = 0.04 √E . Spatial and angular resolutions have been measured as well. The equivalent noise energy was 82 MeV rms for the whole detector.
01 Oct 1984-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the response of a large-area detector and its associated, especially developed, electronics to the energy-loss of single relativistic particles was tested, and it was found that the electronics can be calibrated and can work in showering conditions.
Abstract: In electromagnetic calorimetry large-size silicon detectors, employing relatively low-resistivity (and, therefore, inexpensive) material, can be applied. The energy scale is defined by calibrating the detector with single non-showering relativistic particles. In this experiment the response of a large-area detector and its associated, especially developed, electronics to the energy-loss of single relativistic particles was tested. The electronics can be calibrated and can work in showering conditions. The standard deviation of the Gaussian noise contribution, which included the effect of the detector leakage current, capacitance, charge collection, and cabling, was 99.3 ± 5.3 keV. The energy resolution performance of the electronics, versus the equivalent detector capacitance (180 to 2000 pF), was found to be good. A silicon sandwiched calorimeter is expected to have good energy resolution compared to the conventional sandwiched calorimeters.
TL;DR: A whole body gradient-layer calorimeter was designed for thermophysiologic studies in hospitalized patients and has proven to be reliable, accurate, and easy to operate.
Abstract: A whole body gradient-layer calorimeter was designed for thermophysiologic studies in hospitalized patients. The instrument was assembled in a room adjoining a metabolic ward. The patient lies recumbent on a stretcher which is wheeled into the calorimeter on tracks. Once inside, the patient's head extends through one wall into a clear plastic canopy. The canopy is partially open on one side and is the entry point for fresh air into this open-circuit system. Heat flux transducers in the calorimeter walls, a thermopile in the exit air stream, and a platemeter in conjunction with wet and dry bulb thermometers allow measurement of total, wet, and dry heat losses from the subject. All calorimeter output signals are routed to a microcomputer system which processes the data and provides real-time output of results. A mannequin heat source is used to calibrate the gradient layer. Testing with a variety of wet/dry heat sources indicate total, wet, and dry heat measurements are accurate to within 2-3%. A typical study of resting energy expenditure requires 1 hr, and protocols of up to 6 hr are well tolerated. The calorimeter has proven to be reliable, accurate, and easy to operate. These qualities, combined with good patient tolerance, make it ideal for metabolic studies.
TL;DR: In this article, the heat capacity of a betaine arsenate single crystal was measured near Tc2 by an automatic adiabatic calorimeter and a typical second order phase transition γ-anomaly was observed.
Abstract: The heat capacity of a betaine arsenate single crystal was measured near Tc2 by an automatic adiabatic calorimeter. A typical second order phase transition γ-anomaly is observed. The transition entropy is Δ = 0.65 J/mol/K. the heat capacity jump at TC2 Δ = 21 J/mol/K. The relation between Δ(T) and Ps (T) given by the Landau theory is roughly satisfied.
TL;DR: In this article, enthalpies of vaporization of nonane, 2-methylnonane, 3-methylnane, 4-methyldecane and 2,4,7-trimethyloctane were measured over the temperature range from 328 to 368 K using an adiabatic vaporization calorimeter.
TL;DR: In this article, a flow calorimetric technique for measuring the excess enthalpy of vapors at high temperatures and pressures was developed, which can be used to study highly polar fluid mixtures.
Abstract: Researchers developed a new flow calorimetric technique for measuring the excess enthalpy of vapors at high temperatures and pressures. Excess enthalpies obtained using the new method agree well with those obtained on a well-tested low-pressure mixing calorimeter; thermodynamic analysis of the measurements yields accurate excess volumes and compressibility factors. The new flow mixing calorimeter generates thermodynamic data that are free from adsorption error and makes possible the study of highly polar fluid mixtures.
TL;DR: The ballistic Calvet calorimetry (BC) as mentioned in this paper is a method for determining the enthalpy of vaporization of organic materials at high temperatures, and it has been shown to achieve an accuracy of ±1.0 to ± 1.5 percent when conditions are optimized.
TL;DR: In this article, the enthalpies of vaporization of pyridine and three isomers of methylpyridine were measured over the temperature range from 298 to 368 K with an accuracy of 0.25 per cent, using an adiabatic vaporization calorimeter.
TL;DR: In this paper, a non-linear curve-fitting algorithm was applied to the variable mass case of a calorimeter working with a continuous mixing device to characterize calorimetric systems which uses a nonlinear curvefitting algorithm to approximate their unit pulse response.
TL;DR: Results suggest that heat is evolved instantaneously upon mixing and no heat is produced during aggregation, as may occur in reactions involving monoclonal antibodies.