Calorimeter animal

By far, the most suitable method to quantify individual ruminant animal CH4 measurement is by using respiration chamber, or calorimetry. The respiration chamber models include whole animal chambers, head boxes, or ventilated hoods and face masks. These methods have been effectively used to collect information pertaining to CH4 emissions in livestock. The predominant use of calorimeters has been in energy balance experiments where CH4 has been estimated as a part of the procedures followed. Although there are various designs available, open-circuit calorimeter has been the one widely used. There are various designs of calorimeters, but the most common one is the open-circuit calorimeter, in which outside air is circulated around the animal s head, mouth, and nose and expired air is collected for further analysis. 

Techniques are available to quantify the generation of smoke, toxic and corrosive fire products using the NBS Smoke Chamber (15), pyrolysis-gas chromatography/mass spectrometry (PY-GC-MS) (J 6), FMRC Flammability Apparatus (2,3,5,17,18), OSU Heat Release Rate Apparatus (13) and the NIST Cone Calorimeter (JJO. Techniques are also available to assess generation of 1) toxic compounds in terms of animal response (19), and 2) corrosive compounds in terms of metal corrosion (J 7). In the study, FMRC techniques and AMTL PY-GC-MS techniques were used. 

The famous French scientist Antoine Laviosier (1743-1794) is considered by many to be the first modern chemist. Lavoisier created a calorimeter to study the energy that is released by the metabolism of a guinea pig. To learn about Lavoisier s experiment, go to the web site above and click on Web Links. What do you think about using animals in experiments Write an essay to explain why you agree or disagree with this practice. 

From a thermochemical viewpoint, can a human or animal be regarded as just a catalyst for the combustion of foodstuffs To answer this question, large calorimeters were constructed into which an animal or a human being was placed. If, while in the calorimeter, the subject neither gained nor lost weight, the heat evolved should have been just equal to - AH for combustion of the food consumed to C02, water, and urea. That this prediction was verifed experimentally does not seem surprising, but at the time that the experiments were first done in the early years of the century there may have been those who doubted that the first law of thermodynamics applied to mammals. 

Calorimeters of Historical and Special Interest Around 1760 Black realized that heat applied to melting ice facilitates the transition from the solid to the liquid stale at a constant temperature. For the first time, the distinction between the concepts of temperature and heat was made. The mass of ice that melted, multiplied by the heal of fusion, gives the quantity of heal. Others, including Bunsen, Lavoisier, and Laplace, devised calorimeters based upon this principle involving a phase transition. The heat capacity of solids and liquids, as well as combustion heats and the production of heat by animals were measured with these caloritnelers. 

The term macrocalorimeter is not used very often but will usually imply a vessel volume of 0.1-1 1 and a power sensitivity significantly lower than what is typical for microcalorimeters. A whole body calorimeter is a term used for large, up to room-size, calorimeters employed for direct measurement of heat produced by humans and large animals, sometimes under conditions where the objects are conducting some sort of physical exercise. 

The energy expenditure of an animal or human may also be determined by the method of direct calorimetry. Direct calorimetry requires the use of an insulated room, chamber, or suit for the human or animal. The enclosure contains a water jacket. The water passes from one end of the jacket to the other, maintaining the room, chamber, or suit at a constant temperature. The temperature of the water leaving the jacket is used to calculate the energy expended by the subject. The principles behind the use of the chamber are identical to those behind the use of the bomb calorimeter. The major difference is that in bomb calorimetry combustion is catalyzed by a small spark. In addition, in the bomb calorimeter oxygen is present at a high pressure to facilitate combustion. With direct calorimetry, combustion is catalyzed by enzymes. This combustion proceeds more slowly than that catalyzed by a spark, and the temperature of the subject does not increase much over the normal resting body temperature with the various activities. 

FIGURE 212. Ice calorimeter, designed by Lavoisier and the famous mathematician Laplace. Heat was defined in units of ice melted. The idea that metabolism was similar to combustion derived from the knowledge that oxygen was required, carbon dioxide and water produced and heat generated by animals. Thus, Lavoisier realized that combustion, calcination and metabolism were all related in the sense that each involved combination with oxygen. 

Garcia Payo MC, Ampuero S, Oviedo A, Liu J-S, van Gulik W, Marison IW, von Stockar U (2002) Development and characterization of a bio-reaction calorimeter for animal cell cultures. Thermochim Acta (in press)... 

Because animal calorimeters are expensive to build and earlier types required much labour to operate them, animal calorimetry today is mainly carried out by the indirect method described below. 

The heat lost by animals may be measured directly in an enclosed chamber called an animal calorimeter. Alternatively, it may be estimated from the animal s respiratory exchange (oxygen consumption and carbon dioxide production) in a respiration chamber. 

From the result (p. 430) that i oz. of charcoal forms 3 6715 oz. of fixed air and on combustion evolves heat which melts 6 lb. 2 oz. of ice, the heat evolved in the formation of i oz. of fixed air would melt 26-692 oz. of ice. The 224 grains of fixed air which they found produced in the respiration of the guinea-pig in 10 hours, therefore, corresponds with the production of heat which would melt 10-38 oz. of ice. By putting the animal in the calorimeter it was found that 13 oz. were melted. 

The heat generated by the heart muscle of an animal caimot be measured by placing the entire test animal in a calorimeter. Indeed, all organs produce heat, and the calorimeter cannot distinguish between heat sources. Although seemingly trivial, this example is instructive because it applies to any system that comprises heat flows of various locations - in other words, to all cases in which the heat... 

Applications of the Ice Calorimeter The very first applications of an ice calorimeter were reported by Lavoisier and Laplace (1780) (see Section 1.1.1). They measured the specific heat capacities of solids and liquids, as well as combustion heats and the production of heat by living animals. 

Isoperibol (quasi-isothermal) calorimeters are used in medicine and biology for determinations of the metabolic heats of organisms under various conditions (Dauncey, 1991). Here the calorimeter system (container or chamber) is large enough to accommodate one animal or person in relative comfort. The measurement principle is similar to the upper examples the container for the organism, positioned in thermostatized surroundings, is enclosed in a uniform layer or wall of a heat conductive material, and the temperature difference between the two... 

Such calorimeters have been used to investigate the metabolism of animals (Lamprecht, 1985) and human beings (Tschegg et al, 1981) under different conditions (see also McLean and Tobin, 1987). To our knowledge, there is no commercial manufacturer of this type of device all presently existing whole-body calorimeters are unique constmctions of the respective research group. 

The uncertainty of the given heat production rates is almost totally determined by the fluctuations of the heat production rate measured with different animals and may be characterized by the standard deviation of the mean. The uncertainty of the calorimeter itself is much lower and can, as a rule, be neglected. 

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