The Dalton/amu argument will probably surface after the 2014 CGPM congress (where the redefinition of the kilogram, ampere, kelvin and mole will be discussed - see http://en.wikipedia.org/wiki/New_SI_definitions ). Any dropping of the "l" in favour of "L" for the litre is likely to meet resistance in Europe - it is only the Anglo-Saxons who have a problem with "l" to represent the litre and that is because we do not have a stroke on the number "1" when we handwrite it.
From: [email protected] [mailto:[email protected]] On Behalf Of John M. Steele Sent: 09 April 2013 10:35 To: U.S. Metric Association Cc: U.S. Metric Association Subject: [USMA:52655] Re: Daltons I don't believe the dalton replaced the unified atomic mass unit (symbol "u"). The SI Brochure describes them as alternate names (and symbols) for the same unit. Actually I only looked in NIST SP330, where the dalton is listed first. That may signify it is preferred but the text does NOT explicitly say so. The situation is analogous to two symbols for the liter. "Unified atomic mass unit" is quite a mouthful. I always use dalton and I don't see why the unified atomic mass unit can't be deprecated in favor of the dalton. Of course, I don't see why "l" can't be deprecated in favor of "L", either. The unit is important in chemistry as the amu is approximately the number of proton and neutrons in the nucleus, and the connection between the gram and mole (although the BIPM manages to define the mole without ever mentioning it or Avogadro's number). Binding energy and the averaging over naturally occuring isotopes gives rise to non-integer values. _____ From: Paul Trusten <[email protected]> To: U.S. Metric Association <[email protected]> Cc: U.S. Metric Association <[email protected]> Sent: Tue, April 9, 2013 12:35:05 AM Subject: [USMA:52652] Re: Daltons It takes a long time to achieve de facto deprecation of a unit. If the amu was replaced by the dalton in 1961, no one reached the authors of my first science textbooks or teachers with the news (1965). In fact, I never heard of the dalton until the mid-seventies, so we shall probably continue struggling with that old name for Celsius for a while to come, too, even 65 years after its deprecation. Paul Trusten, Reg. Pharmacist Vice President U.S. Metric Association, Inc. Midland, Texas USA www.metric.org +1(432)528-7724 [email protected] On Apr 8, 2013, at 20:29, Michael Payne <[email protected]> wrote: > Interesting Unit at http://en.wikipedia.org/wiki/Insulin-like_growth_factor_1 > > forth paragraph down: > > IGF-1 consists of 70 amino acids in a single chain with three intramolecular disulfide bridges. IGF-1 has a molecular weight of 7,649 daltons. > > There is another page on Daltons http://en.wikipedia.org/wiki/Dalton_%28unit%29 A unit accepted for use with SI, seems with the prefixes we have, some sub unit of a gram would have been equally good. Or is this something like the Astronomical unit on the other end of the scale? > > Michael Payne > >
