Thursday, April 30, 2009

Naming a flu: from 'swine flu' to '2009 H1N1 flu'

In April 2009, a flu outbreak in Mexico City, spreading into other areas and countries, made headlines. In the beginning, this flu was generally termed swine flu, although affecting humans. The H1N1 strain of the flu virus was found to be a mixture of genetic material from swine, bird and human flu strains. U. S. public health officials dropped the term swine flu in favor of 2009 H1N1 flu, which is a neutral and descriptive notation. The World Health Organization (WHO) decided to stick with the term swine influenza. Other suggested terms such as North American flu and Mexican flu are controversial and inappropriate and shoud be avoided—as most people will probably agree.

Friday, April 10, 2009

The adjectives alternate and alternative

The adjectives alternate and alternative may look and sound similar, but have different meanings:

alternate: occurring in a successive or replacing manner
alternative: different from the usual, conventional or accepted

The word alternative can also be a noun, as in the following sentence:
An alternate traveling route is suggested as an alternative to the most frequently taken route.

Ph vs. pH

Upper and lower case is often critical. In chemistry, the symbol Ph is frequently used to represent a phenyl group, whereas pH stands for potentium Hydrogenium (Latin for potential of hydrogen). The pH value of a solution measures its acidity or basicity. The quantity pH is dimensionless and defined as the negative value of the decimal logarithm of the hydrogen ion activity, aH, in an aqueous solution:

pH = -log10 aH

For pH details see: IUPAC Gold Book/pH quantity

Thursday, April 9, 2009

steric, sterical and sterically

The words steric and sterical are both adjectives, having the same meaning: relating to the spatial arrangement of atoms and groups in a molecule or ligands in a chemical complex. The corresponding adverb is sterically. The derived adverb stericly is not often used. Common phrases are sterically hindered and sterically stabilized.