free energy (redirected from Gibbs free energy)

energy /en·er·gy/ (en´er-je) power which may be translated into motion, overcoming resistance, or effecting physical change; the ability to do work. Symbol E.

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free energy , Gibbs free energy (G ) that equal to the maximum amount of work that can be obtained from a process occurring under conditions of fixed temperature and pressure.

kinetic energy  the energy of motion.

nuclear energy  energy that can be liberated by changes in the nucleus of an atom (as by fission of a heavy nucleus or fusion of light nuclei into heavier ones with accompanying loss of mass).

potential energy  energy at rest or not manifested in actual work.

vital energy  see under force.

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free energy

n.

A thermodynamic quantity that is the difference between a system's internal energy and the product of its absolute temperature and entropy; the portion of total energy of a natural system that can be used for work.

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energy

power that may be translated into motion, overcoming resistance, or effecting physical change; the ability to do work. Energy assumes several forms; it may be thermal (in the form of heat), electrical, mechanical, chemical, radiant or kinetic. In doing work, the energy is changed from one form to another or to several forms. In these changes some of the energy is 'lost' in the sense that it cannot be recaptured and used again. Usually there is loss in the form of heat, which escapes or is dissipated unused. All energy changes give off a certain amount of the energy as heat.

All activities of the body require energy, and all needs are met by the consumption of food containing energy in chemical form. The animal diet comprises three main sources of energy: carbohydrates, proteins and fats. Of these three, carbohydrates most readily provide the kind of energy needed to activate muscles. Proteins work to build and restore body tissues. The body transforms chemical energy derived from food by the process of metabolism, an activity that takes place in the individual cell. Molecules of the food substances providing energy pass through the cell membrane. Inside the cell, chemical reactions occur that produce the new forms of energy and yield by-products such as water and waste materials. See also adenosine.

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dietary energy

the total energy intake in the diet is the gross energy. Digestible energy is gross energy less fecal energy. Metabolizable energy is digestible energy less that lost in fermentation in the gut, energy lost in urine. Net energy is metabolizable energy less energy used in specific dynamic action response. Expressed as joules, calories or occasionally therms (1 calorie=4.18 joule).

energy density

see caloric density.

energy feeds

feeds with a high carbohydrate content and therefore low fiber (<18%) and protein (<20%) contents.

free energy

the energy equal to the maximum amount of work that can be obtained from a process occurring under conditions of fixed temperature and pressure.

nuclear energy

energy that can be liberated by changes in the nucleus of an atom (as by fission of a heavy nucleus or by fusion of light nuclei into heavier ones with accompanying loss of mass).

nutritional energy deficiency

causes loss of body weight, milk, egg and wool production. Continued for long periods or severe restriction causes particular metabolic upsets in pregnant and lactating ewes and cows—see pregnancy toxemia, acetonemia (2); in neonates, hypoglycemia. In others causes emaciation, inanition, starvation.

energy production

production of ATP through oxidative phosphorylation or anaerobic glycolysis.

energy requirements

generally vary between species and particularly between individuals. They are determined by many factors, especially age, level of activity, physiological status and body size, specifically body surface area. The basal energy requirement (BER) is the level required by a healthy animal at complete rest in a neutral environmental temperature. It can be calculated by using several formulae, based on body weight or body surface area, which is then used in the further calculation of the maintenance energy requirement (MER) which takes into account the individual animal's level of activity or disease status.

energy reserves

any reduced carbon stored in compounds such as fatty acids in triacylglycerols of adipose tissue, glucose in glycogen, and amino acids in protein releases energy, ultimately in the form of ATP on oxidation of the carbon.

energy transfer

conversion of energy from one form usually chemical in the form of ATP to another usually chemical, but can be electrical, mechanical or heat energy.