Caloric problems

There is a problem with Carnot s analysis, however, since at that time almost all physicists (including Carnot) thought heat consisted of a substance called caloric, which could not be created or destroyed. As a result, the amount of heat taken from the hot source at temperature T, would have to be the same as that delivered to the cold reservoir at temperature T(. Because no heat was converted into work, the efficiency of such an engine would be zero. 

Foods that yield in the range of 5-10 calories/g protein should be excellent dietary sources of protein. However, those that yield 50-100 or more calories/g protein should probably be used more where calories for energy are needed and supplemented with other protein sources. In many countries man has supplemented his diet with protein by the consumption of animal products and meat in order to eliminate this problem and balance the protein-caloric values. 

The calculation of AG from the caloric data is straightforward, independent of the path, that is, whether the reaction takes place in a single step or through a series of steps by using Hess s law and Nernst heat theorem [15-17]. Furthermore, we can calculate AG for the reaction of interest from the combination of other reactions involved for which the thermodynamic data are known. However, both the initial and final states in many cases are hypothetical. Even in the case of measurements executed very carefully and accurately, there might be problems in defining the states of the compounds, or even metals ( ) that take part in the reaction. 

While many of the poorer people on earth starve to death the problems of atherosclerosis and obesity affect many in wealthier societies.2533-0 Tire fat content of foods is often blamed, and, as discussed in Boxes 21-B and 22-B, the quality of fatty acids in the diet is very important. However, like fatty acids, carbohydrates are also metabolized via acetyl-CoA and can readily be converted to both fatty acids and cholesterol.2534 Obesity is largely a problem of excessive total caloric intake. 

Impact of a gas by a piston with subsequent gas dispersion into a vacuum is an extremely idealized statement of the problem. A more realistic problem is to consider a thin flat layer of explosive dividing two gas regions one with initial density p0 (in which we consider the motion) located to the right at x > 0, and one with initial density R, Rexplosive material is indicated by the 1). The mass of the explosive per unit surface we denote by m, and its caloricity (specific energy in erg/g) by Q. Following M. A. Lavrentiev, we break the beginning of the process into stages. 

The numbers quoted in Table 8.4 are not very precise, and different reference sources often give different values. Part of the problem is that the source and variety of the food can cause large differences—an "apple," for instance, may be any one of over a hundred varieties and may come from practically any country on Earth. Perhaps even more important is that many foods—carbohydrates such as bread, in particular—contain a large but variable amount of water, which increases the mass of the food but adds no caloric value. 

Chick edema disease became a serious economic problem by the mid-1950s, by which time millions of broilers had succumbed to it in the U.S. The problem was traced to toxic components in the unsaponifiable fraction of certain low cost feed fats Introduced into the chick diet to increase the caloric intake (ref. 121c). Symptoms included fluid in the heart sack and abdominal cavity, subcutaneous edema and liver necrosis. Injection of purified chick edema factor into fertile eggs resulted in lower hatch yield, embryonic deformities and edema. Unhatched embryos exhibited a variety of defects (malformed beaks, leg deformities, no development of the right mesencephalon, and eye defects). Hatched embryos were growth-retarded, with sparse and defective feathers. The isolated toxin was ultimately identified as 1.2,3,7.8,9-... 

The instrument that Lavoisier used with the greatest success to demonstrate the truth of his system was the balance, an instrument with a beam pivoting on a central knife-edge, with a scale pan at each end. Chemical substances are neither created nor destroyed during reactions, and this truth can be shown to hold for any substance that has weight. We shall see later that Lavoisier needed a different instrument to try to show that caloric, the matter of heat, behaved as a simple substance in chemical reactions. This was a problem precisely because caloric had no weight. 

The differential forms of the conservation equations derived in the appendixes for reacting mixtures of ideal gases are summarized in Section 1.1. From the macroscopic viewpoint (Appendix C), the governing equations (excluding the equation of state and the caloric equation of state) are not restricted to ideal gases. Most of the topics considered in this book involve the solutions of these equations for special flows. The forms that the equations assume for (steady-state and unsteady) one-dimensional flows in orthogonal, curvilinear coordinate systems are derived in Section 1.2, where specializations accurate for a number of combustion problems are developed. Simplified forms of the conservation equations applicable to steady-state problems in three dimensions are discussed in Section 1.3. The specialized equations given in this chapter describe the flow for most of the combustion processes that have been analyzed satisfactorily. 

Results showed that jojoba oil is not fuUy hydrolyzed by the pancreatic lipase because of its structure. Weight gain data in rats showed that jojoba oil has a low-caloric value compared with com oil (67). There were problems associated with the consumption of jojoba oil. For instance, in rat feeding trials, anal leakage, depression, weakness, and death were observed when jojoba oil was fed at moderate-to-high doses (67). Animal studies with jojoba oil also showed that approximately 40% of the oil was absorbed (67), and therefore might serve as a low-calorie replacement for edible fats and oils in food use provided this compound was proven safe for food applications. Hence, possible applications of this oil are in control of obesity and calories. 

Blockage of the bile duct caused by problems such as cholesterol-containing gallstones or duodenal or pancreatic tumors can lead to an inadequate concentration of bile salts in the intestine. Digestion and absorption of dietary lipids is diminished. Certain diseases that affect the pancreas can lead to a decrease in bicarbonate and digestive enzymes in the intestinal lumen. (Bicarbonate is required to raise the intestinal pH so that bile salts and digestive enzymes can function.) If dietary fats are not adequately digested, steatorrhea may result. Malabsorption of fats can lead to caloric deficiencies and lack of fat-soluble vitamins and essential fatty acids. 

A problem for many people in the United States is excess body weight stored as fet. Many persons have tried to capitalize on this problem with fruitless weight-loss schemes. However, since energy is conserved, an energy balance reveals only two real ways to lose weight (other than water loss) (1) reduce the caloric intake, and/or (2) increase the caloric expenditure. In answering the following questions, assume that fet contains approximately 7700 kcal/fcg (1 kcal is called a dietic calorie in nutrition, or commonly just calorie ). 

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