Units and quantities

It will be assumed that readers are familiar with the use of exponents, particularly powers-of-ten notation, and with the rules for significant figures. If not. Appendices A and B should be studied in conjunction with Chapter 1. 

Considerable progress is being made in the acceptance of a common international system of reference units within the world scientific community. This system, known as SI from the French name, Systeme International d Unites, has been adopted by many international bodies, including the International Union of Pure and Applied Chemistry. In SI, the reference units for length, mass, and time are the meter, kilogram, and second, with the symbols m, kg, and s, respectively. 

To express quantities much larger or smaller than the standard units, use may be made of multiples or submultiples of these units, defined by applying as multipliers of these units certain recommended powers of ten, listed in Table 1-1. The multiplier abbreviation is to precede the symbol of the base unit without any space or punctuation. Thus, picosecond (10 s) is ps, and kilometer (10 m) is km. Since for historical reasons the SI reference unit for mass, kilogram, already has a prefix, multiples for mass should be derived by applying the multiplier to the unit gram rather than to the kilogram. Thus 10 kg is a microgram (10 g), abbreviated qg. 

Compound units can be derived by applying algebraic operations to the simple units. 

EXAMPLE 1 The unit for volume in SI is the cubic meter (m ), since 

All new legislation in force after 1986 is required by the Units of Measurement Regulations 1980 to be in SI units. Only the SI system of imits is described in full here, although tiie relationships between the old and new units are given in Table 3.4.1. 

The activity of an amount of a radionuclide is given by the rate at which spontaneous decays occur in it. Activity is expressed in a unit called the becquerel, Bq. A Bq corresponds to one spontaneous decay per second. Multiples of tire becquerel are frequently used such as the megabecquerel, MBq (a million becquerels). 

The absorbed dose is the mean energy imparted by ionising radiation to the mass of matter in a volume element. It is expressed in a unit called the gray, Gy. A Gy corresponds to a joule per kilogram. 

Quantity New named In other Old unit Conversion factor 

General gas constant, R Loschmidt (Avogadro) number, N (number of particles per mol) 

Koolman, Color Atlas of Biochemistry, 2nd edition 2005 Thieme All rights reserved. Usage subject to terms and conditions of license. 

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Symbols separated by commas represent equivalent recommendations. Symbols for physical and chemical quantities should be printed in italic type. Subscripts and superscripts which are themselves symbols for physical quantities should be italicized all others should be in Roman type. Vectors and matrices should be printed in boldface italic type, e.g., B, b. Symbols for units should be printed in Roman type and should remain unaltered in the plural, and should not be followed by a full stop except at the end of a sentence. References International Union of Pure and Applied Chemistry, Quantities, Units and Symbols in Physical Chemistry, Blackwell, Oxford, 1988 Manual of Symbols and Terminology for Physicochemical Quantities and Units, Pure Applied Chem. 31 577-638 (1972), 37 499-516 (1974), 46 71-90 (1976), 51 1-41, 1213-1218 (1979) 53 753-771 (1981), 54 1239-1250 (1982), 55 931-941 (1983) lUPAP-SUN, Symbols, Units and Nomenclature in Physics, PV ica 93A 1-60 (1978). 

International Union for Pure and AppHed Chemistry (lUPAC) Bank Court Way, Cowley Centre Oxford 0X4 3YP United Kingdom Among its pubheations in the standards field are Manual of Symbols and Terminologyfor Physico-chemical Quantities and Units, D. H. Whiffen, ed., Pergamon, New York, 1979, and Nomenclature of Inorganic Chemisty, Pergamon, New York, 1977. 

International Union of Pure and AppHed Chemistry, Manual of Symbols and Terminologyfor Physicochemical Quantities and Units, Pergamon Press, Oxford, UK, 1919, Pure AppI Chem. 51, 1 (1979). 

Constants and factors are often supplied by the manufacturer. Separate constants may be given for converting the stress and shear rate terms to the correct quantities and units. 

Composition by mol%, volume %, or weight %. To what extent does composition vary Corrosive effects. Limits to discharge temperature, which may cause problems with the gas. Quantity to Be Handled, for Each Stage Stage quantity and unit of measurement. 

IUPAC Manual of Symbols and Terminology for Physicochemical Quantities and Units, Butterworth, London, 1969... 

Dybkaer R, Storring PL (1995) Application of lUPAC-lFCC recommendations on quantities and units to WHO biological reference materials for diagnostic use. Europ J Clin Chem Clin Biochem 33 623-625. 

Manual of symbols and terminology for physico-chemical quantities and units. Appendix III. Electrochemical nomenclature. Pure Appl. Chem., 37, 499 (1974). 

Scientists measure many different quantities—length, volume, mass (weight), electric current, temperature, pressure, force, magnetic field intensity, radioactivity, and many others. The metric system and its recent extension, Systeme International d Unites (SI), were devised to make measurements and calculations as simple as possible. In this chapter, length, area, volume, and mass will be introduced. Temperature will be introduced in Sec. 2.7 and used extensively in Chap. 11. The quantities to be discussed here are presented in Table 2-1. Their units, abbreviations of the quantities and units, and the legal standards for the quantities are also included. 

Since 1925, The International Commission on Radiation Units and Measurements at Bethesda, Maryland has been publishing reports updating the definitions and units for measurements of various radiation-related quantities. Of these ICRU Reports, special mention may be made of reports no. 19 (1971) [radiation quantities and units], 33 (1980) [radiation quantities and units], 36 (1983) [microdosimetry], 47 (1992) [thermoluminiscent dosimetry], and 51 (1993) [radiation protection dosimetry]. A succinct description of various devices used in dosimetry, such as ionization chambers, chemical and solid-state dosimeters, and personnel (pocket) dosimeters, will be found in Spinks and Woods (1990). In this section, we will only consider some chemical dosimeters in a little detail. For a survey of the field the reader is referred to Kase et at, (1985, 1987), McLaughlin (1982), and to the International Atomic Energy Agency (1977). Of the earlier publications, many useful information can still be gleaned from Hine and Brownell (1956), Holm and Berry (1970), and Shapiro (1972). 

Collect, analyze, develop, and disseminate in the public interest information and recommendations about (a) protection against radiation and (b) radiation measurements, quantities, and units, particularly those concerned with radiation protection ... 

Radiation Quantities and Units International Commission on Radiological Units and Measurements Bethesda, 1980 Report No. 33. 

M. A. Paul, International union of pure and applied chemistry. Manual of Symbols and Terminology for Physicochemical Quantities and Units, Butterworth, London, 1975. B. N. Taylor, ed.. The International System of Units, 7th ed., NIST Special Publication 330 (2001), http //physlab.nist.gOv/Pubs/SPS330/sps330.html. 

The International Union of Puie and AppUed Chemistry now recommends a standard pressure of 0.1 MPa (1 bar) in place of the previously accepted standard of 101.325 kPa (1 atm). The difference in thermodynamic quantities is not significant for condensed phases, and differences in A// values are not significant even for gases, but the user of thermodynamic tables will have to note carefully the standard state chosen for any compilation of data. See Ref. 1, pp. 2—23 lUPAC Division of Physical Chemistry, Commission on Symbols, Terminology and Units, Manual of symbols and terminology for physico-chemical quantities and units, M. L. McGlashan, M. A. Paul, and D. N. Whiffen, eds., Pure andApp. Chem 51, 1 (1979), and Appendix IV, Pure and Applied Chem. 54, 1239 (1982). 

TABLE 1 Comparison of Additive Quantities and Unit Cost... 

The concept and quantity absorbed dose were introduced by the ICRU in 1951, with the special unit rad. A new special unit gray (Gy) was introduced in 1972 to be in correspondence with the SI system of quantities and units (Systeme International des Grandeurs et Unites) [11,12]. 

International Commission on Radiation Units and Measurements (ICRU). Quantities and Units in Radiation Protection Dosimetry, ICRU Report 51 Bethesda, Maryland, 1993. International Commission on Radiation Units and Measurements (ICRU). Fundamental Quantities and Units for Ionizing Radiation, ICRU Report 60, Bethesda, Maryland, 1998. Wambersie A. Menzel H.G. Gahbauer R.A. Jones D.T.L. Michael B.D. Paretzke H. Radiat. Prot. Dosim. 2002, 99, 445. 

Throughout this work SI units have been used, with the exception of pressure, which is given in Torr. For formulae, table headings etc. the Quantity Calculus has been used, as advised by M. L. McGlashan, Physicochemical Quantities and Units, Royal Society of Chemistry Sales and Promotions Department, Burlington House, London, WIV OBN. 

Some self-contained instruments are designed for on-line measurements in UV curing units to determine the integral UV dose delivered to the material being cured, peak irradiance, and irradiance/temperature profiles. The quantities and units of measurements have been established based on lUPAC s recommendation of 1996. These are listed in Table 9.3. 

ICRU (1980). International Commission on Radiation Units and Measurements. Radiation Quantities and Units, ICRU Report No. 33 (International Clommission on Radiation Units and Measurements, Bethesda, Maryland). 

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