Quantities, symbols, and units

high-resolution terminology - matching measurements at high-resolution

Quantities, symbols, and units

Description

Quantities, untis, and symbols

MitoPedia concepts: MiP concept, "MitoFit Quality Control System" is not in the list (MiP concept, Respiratory state, Respiratory control ratio, SUIT concept, SUIT protocol, SUIT A, SUIT B, SUIT C, SUIT state, Recommended, ...) of allowed values for the "MitoPedia concept" property. MitoFit Quality Control System"MitoFit Quality Control System" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property.

MitoPedia topics: BEC

‘When a code is familiar enough, it ceases appearing like a code; one forgets that there is a decoding mechanism. The message is identical with its meaning’ (Hofstadter 1979 Harvester Press)

Symbols are used as a code for physicochemical quantities. Simple symbols — such as Q or N — are used with different meanings depending on context. When the context is expanded, the symbols have to be expanded, including more detail to avoid confusion. Then symbols may appear confusingly complicated, loosing the function of sending their message quickly. There is no single best way to design the right symbol — all depends on context. The medium is the message, the message is the meaning (from Marshall McLuhan to [[Hofstadter 1979 Harvester Press |Hofstadter]]).

Extensive quantities

cell count	Count	N_ce	[x]	Tab. 4; Fig. 5; see number of cells; countable object X=ce
amount of substance X	Amount	n_X or n(X)	[mol]	SI; amount n of X versus count N of X
electric charge	Electric charge	Q_el	[C]	SI; Q_el = I_el [A] · t [s]; Q_el versus Q_th
cell mass	Body mass	m_ce	[kg]	Tab. 5; Fig. 5; mass of cells m versus mass per cell (per cell count) M_{N_ce}

Per count

elementary charge	Elementary charge	e	[C·x^-1	SI; e = Q_B·N_B
electric charge per substance	Electric charge	Q_B	[C·x^-1]	Q_B is the electric charge per entity B; Q_O₂ = 4 C·x^-1. IUPAC does not define the symbol Q_B separately, but uses it in Section 2.13 in the definition of charge number, z_B = Q_B·e^-1; therefore, Q_B = z_B·e. The symbol Q signals the extensive quantity Q_el [C], whereas the subscript B in this case signals 'per count of B' (per N_B). This causes confusion: Compare V_O₂ [L] which is the volume of O₂ in a sample, where the subscript O₂ contains the message of entity type X=O₂. In contrast, Q_O₂ cannot be understood as charge per substance, if the subscript O₂ contains only the message of entity type X=O₂ (as in V_O₂), but subscript O2 has the meaning of 'divided by N_O₂', confusing the symbol for an entity type X=O₂ with the number of a single elementary entity, N_X = N_O₂ = 1 x. X ≠ N_X.
charge number per entity B	Charge number	z_B	1	z_B = Q_B·e^-1 (IUPAC); z_O₂ = = Q_O₂·e^-1 = 4; IUPAC uses the term 'charge number of an ion' which should be changed to 'charge number per ion', or more clearly to 'charge number per ion number'. The symbol z carries the message 'number of elementary charges per number', and the subscript carries the message on the type of entity
cell mass, mass per cell	Body mass	M_{N_ce}	[kg∙x^-1]	Tab. 5; Fig. 5; mass per cell count M_{N_ce}; upper case M and subscript N signal 'per count', subscript ce signals the entity X=ce

Per voume: density and concentration

cell-count concentration	Concentration	C_ce	[x∙L^-1]	Tab. 4; C_ce = N_ce∙V^-1; count concentration C versus amount concentration c; subscript indicates the entity X=ce, but does not signal 'per entity' ('per entity' can only mean 'per count of entity')
cell-mass concentration in chamber	Concentration	C_{m_ce}	[kg∙L^-1]	see C_{m_s}: Tab. 4; C_{m_ce} = m_ce∙V^-1; upper case C alone signals 'count concentration' (C_N would be more explicit), whereas the signal for 'mass concentration' is in the combination C_m