SUBJECTS Thomson effect

It is necessary to define the conception of the inversion temperature a little more closely. In the literature of the subject we find this term used with two distinct meanings first, as the temperature at which the Joule-Thomson effect vanishes when the gas is allowed to expand from a high pressure p to the pressure of the atmosphere, and, secondly, as the tempera-... 

Thomson NC, Kerr JW Effect of inhaled Hj and H2 receptor antagonist in normal and asthmatic subjects. Thorax 1980 35 428-434. 

The Curie brothers were drawn to the subject of piezoelectricity because of their familiarity with a phenomenon known for many centuries, that of pyroelectricity. Pyroelectricity refers to the tendency of certain materials to generate an electric current when they are heated. The phenomenon was first described in 314 b.c.e. by the Greek philosopher Theophrastus (ca. 370-ca. 285 b.c.e.), who observed the effect with the mineral tourmaline. Little research was done on pyroelectricity until the early 1800s, when the effect was rediscovered and studied in detail by the Scottish physicist Sir David Brewster (1781-1868). Then in 1878, William Thomson, Lord Kelvin (1824-1907), offered an explanation of the atomic changes that take place when pyroelectric effects occur. These developments in the understanding of pyroelectricity led the Curie brothers to study the possibility of producing electricity from crystals by physical means other than heating. 

Ocular Effects. Ocular effects can occur as a result of direct contact of eyes with chromium compounds. These include corneal vesication in a man who got a drop or a crystal of potassium dichromate in his eye (Thomson 1903) and congestion of the conjunctiva, discharge, corneal scar, and burns in chromate production workers as a result of accidental splashes (PHS 1953). Higher incidences of subjective complaints of eye irritation were reported by housewives who lived near a chromium slag construction site than by controls (Greater Tokyo Bureau of Hygiene 1989). 

In the case of a free electron, nothing prevents it from moving, since it is subjected to no outside force. Hence, the predominant effect is Compton scattering. However, it can be shown that the intensity of this scattering effect is accurately described by Thomson s relation. When considering a set of free electrons, the different waves scattered by these electrons have different wavelengths and therefore do not lead to interference effects. What we observe is merely the sum of the scattered intensities. 

The same result can be obtained by nebuUzation of an analyte solution into small droplets that are then flash heated by exposure to hot gas, as in thermospray and APCI sources. Thus, it is conamon to find that a compound that will not 5deld a meaningful mass spectrum using conventional Cl (solid sample heated in an insertion probe) will do so when subjected to flash heating in APCI. Anotber physical phenomenon that contributes to this effect is the increase of vapor pressure of an analyte as the sample size becomes very small, as in a nebulized solution. This increase is described by the Kelvin equation (Thomson 1871, Moore 1972) ... 

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