The need for standards in scientific communication has grown even more pressing as values of physical properties, i.e. data, are now being incorporated in large-scale Cobimetinib cell line efforts such as the Brenda ( Schomburg et al., 2000) and Sabio-RK ( Wittig et al., 2012) databases. Additionally, the entries in these databases are often used for calculations of other properties and for further applications which impact progress in science,

health, and the economy. Thus, standards are needed in essentially all areas of science. The most useful and definitive source of information on nomenclature for quantities, symbols, and units pertinent to physical chemistry is Quantities, Units and Symbols in Physical Chemistry ( Cohen et al., 2007). This publication, which was prepared under the auspices of the Union of Pure and Applied Chemistry (IUPAC),

traces its origin to the Manual of Symbols and Terminology for Physicochemical Quantities and Units, which was prepared in 1970. There have been several editions published between the 1970 Manual ( McGlashan, 1970) and the most recent edition of Quantities, Units and Symbols in Physical Chemistry ( Cohen et al., 2007). Since all of these editions have been published with a green cover, the publication is often referred to as the Green Book. The current edition of the Green Book ( Cohen et al., 2007) is broad Sunitinib nmr in scope and covers a wide variety

of topics such as mechanics (classical and quantum), electricity and magnetism, spectroscopy, electromagnetic radiation, general chemistry, thermodynamics, kinetics, and transport properties. Of fundamental Fludarabine ic50 importance to science and to the system of units are the concept of measurement and the use of quantity calculus. The system of SI units is based on seven base quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity. All other physical quantities are derived from these base quantities. Physical quantities are represented as the product of a number and a unit and they follow the rules of mathematics. Thus, if the concentration of a solute is c=0.0010 mol dm−3, one can write c/(mol dm−3)=0.0010 or 103c/(mol dm−3)=1.0. In the last two representations, the right side of the equation is a number. This emphasizes the fact that the result of an experiment is a ratio of the measured quantity to the value of some standard quantity, which, in this case is 1.0 mol dm−3. In some usage, one sees c (mol dm−3)=0.001. However, it is formally incorrect. While there is little chance of confusion in this case, confusion arises often in regards to powers of 10 in table headings. For example, using the previously used value of c, if one were to write 10−3c=1.0, one formally has c=1000 mol dm−3.