| Kfc | filtration coefficient |
|---|---|
| m/r | mass attenuation coefficient |
| PC | avoirdupois weight [Lat. pondus civile]; packed cells; paper chromatography; paracortex; parent cell... |
| f | Greek letter phi; magnetic flux; osmotic coefficient |
| PMCC | product-moment correlation coefficient [Pearson] |
| radiotherapy, high-energy | Radiotherapy using high-energy (megavolt or higher) ionizing radiation. Types of radiation include gamma rays, produced by a radioisotope within a teletherapy unit; X-rays, electrons, protons, alpha particles (helium ions) and heavy charged ions, produced by particle acceleration; and neutrons and pi-mesons (pions), produced as secondary particles following bombardment of a target with a primary particle. (12 Dec 1998) |
|---|---|
| Parallel Electron Energy Loss Spectroscopy | <technique> Electron energy loss spectroscopy analyses the inelastically scattered electrons present in the beam after it has been transmitted through the sample. An electron energy loss spectrum typically consists of a monatomic decreasing background on which are superimposed a number of peaks. Each peak is characteristic of the scattering process that has occurred in the sample. The peaks can be used to obtain information about the chemical composition and electronic structure of the sample. Electron energy loss spectra are acquired typically in a magnetic sector spectrometer located under the camera chamber of the transmission electron microscope. Spatial resolution is typically limited by the minimum probe diameter of the microscope. Electron energy loss spectroscopy tends to be complimentary to EDS in that it can be used to analyse very thin samples of low Z materials. Acronym: PEELS (05 Aug 1998) |
| geothermal energy | Energy derived from the natural heat of the Earth contained in hot rocks, hot water, hot brines or steam. (05 Dec 1998) |
| Gibbs energy of activation | The Gibbs energy that must be added to that already possessed by a molecule or molecules in order to initiate a reaction. (05 Mar 2000) |
| gibbs free energy | The total amount of energy which is either used up or released during a chemical reaction. Gibbs free energy (delta G) = (delta H) - t (delta s): where (delta H) is the change in enthalpy, calculated by adding up the amount of energy released or used up to break or form chemical bonds during the reaction, t is the temperature at which the reaction took place, and (delta S) is the change in entropy, or amount of disorder, that occurs in the molecules involved during the reaction. (09 Oct 1997) |
| renewable energy resource | <ecology> An energy resource replenished continuously or that is replaced after use through natural means. Sustainable energy. Renewable energy resources include bioenergy, solar energy, wind energy, geothermal power, and hydropower. (25 Jun 1999) |
| chemical energy | Energy liberated or absorbed by a chemical reaction, e.g., oxidation of carbon, or absorbed in the formation of a chemical compound. (05 Mar 2000) |
| conservation of energy | The principle that the total amount of energy in a closed system remains always the same, none being lost or created in any chemical or physical process or in the conversion of one kind of energy into another, within that system. (05 Mar 2000) |
| conservation of energy resources | Planned management, use, and preservation of energy resources. (12 Dec 1998) |
| potential energy | <chemistry> Energy due to position, it is stored energy which can be used to do work. (09 Jan 1998) |
| primary energy | <radiobiology> Energy before conversion. For instance, the United States uses about 30,000 megajoules of electricity per capita per year, but electricity is generally obtained by converting other forms of energy (primarily chemical/heat) at an efficiency of around 30%, so the U.S. Consumes 90,000 megajoules of primary energy per capita for electrical use. (Total U.S. Primary energy consumption is 300,000 megajoules per capita.) (09 Oct 1997) |
| Helmholtz energy | Energy equivalent to the internal energy minus the entropy contribution (TS). (05 Mar 2000) |
| protein-energy malnutrition | The lack of sufficient energy or protein to meet the body's metabolic demands, as a result of either an inadequate dietary intake of protein, intake of poor quality dietary protein, increased demands due to disease, or increased nutrient losses. (12 Dec 1998) |
| high energy bond | <chemistry> Chemical bonds that release more than 25kJ/mol on hydrolysis: their importance is that the energy can be used to transfer the hydrolysed residue to another compound. The risk in using the term is that students may think the bond itself is different in some way, whereas it is the compound that matters. Hydrolysis of creatine phosphate yields 42.7kJ/mol, of phosphoenolpyruvate, 53.2, ATP to ADP, 30.5: the latter is important because it shows that energetically the hydrolysis of creatine phosphate will suffice to reconstitute ATP, hence the use of creatine phosphate in muscle. (18 Nov 1997) |
| high energy compounds | Classically, a group of phosphoric esters whose hydrolysis takes place with a standard free energy change of -5 to -15 kcal/mol (or, -20 to -63 kJ/mol) (in contrast to -1 to -4 kcal/mol or, -4 to -17 kJ/mol) for simple phosphoric esters like glucose-6-phosphate or alpha-glycerophosphates), thus being capable of driving energy-consuming reactions in living cells or reconstituted cell-free systems; adenosine 5'-triphosphate, with respect to the beta-and gamma-phosphates, is the best known and is regarded as the immediate energy source for most metabolic syntheses. The general types are acid anhydrides, phosphoric esters of enols, phosphamic acid (R-NH-PO3H2) derivatives, acyl thioesters (e.g., of coenzyme A), sulfonium compound's (R3-S+), and aminoacyl esters of ribosyl moieties. See: high energy phosphates. (05 Mar 2000) |