From: "Barry L. Ornitz" <ornitz+U@dpnet.net>
Subject: Re: Questions concerning biological effects mobile phones have on  
	humanbody
Date: 16 Feb 1999
Newsgroups: sci.electronics.design,sci.electronics.repair

Michael Lee wrote in message <7aa04v+ACQ-9gb+ACQ-1+AEA-plutonium.btinternet.com>...
>RF and microwave frequencies are known to have a catalytic effect on some
>chemical reactions, and it is therefore reasonable to suspect that they may
>have some effects on the physiological chemistry of the brain.


At the frequencies we are talking about, the only effect they have on
chemical reactions is totally thermal.  You have to increase the
frequencies into the infrared to excite chemical bonds.  And you have to go
to much shorter wavelengths still to have interactions with the nuclei.

Low frequencies can have large effects on biological systems, but the
effect falls off as the reciprocal of frequency.  This is because chemical
ions will migrate in an electrostatic field.  By the time you increase the
frequency to the AM broadcast band, the ions have so much inertia that they
cannot move to follow the polarity changes.

        Dr. Barry L. Ornitz     ornitz+AEA-dpnet.net

From: "Barry L. Ornitz" <ornitz+U@dpnet.net>
Subject: Re: Questions concerning biological effects mobile phones have on  
	humanbody
Date: 16 Feb 1999
Newsgroups: sci.electronics.design

Dirk Bruere wrote in message <36C9DE28.1127E490@kbnet.co.uk>...
>Barry L. Ornitz wrote:
>>
>> At the frequencies we are talking about, the only effect they have on
>> chemical reactions is totally thermal.  You have to increase the
>> frequencies into the infrared to excite chemical bonds.  And you have to go
>> to much shorter wavelengths still to have interactions with the nuclei.
>>
>
>I think that's a little misleading in the sense that it sounds like it's
>just another substitute for a Bunsen burner.
>
>For more info
>
>http://www.ed.ac.uk/~ah05/microwave.html
>
>Dirk

You did not read the information from this site very well, did you?  In
every instance Gavin Whitaker has found a thermal explanation of why
microwave heating may speed a reaction.  [About 9 or more years ago,
Whitaker was just starting in his research.  He posted on the sci.chem
group and I gave him quite a bit of advice on the overall issue of
dielectric heating.  In those days, he very much wanted to believe in a
"special magic" to microwave heating.  It is quite obvious now that the
more he learned, the faster he quit believing this.]

In most cases, the microwave *IS* just a substitute for a Bunsen burner.
But because the heat is generated internally, and does not have to diffuse
in from the surface by conduction or convection, it can heat many things
much faster than conventional heating.  This is the effect you see on
chemical reaction rates - purely thermal.  Many chemists also did their
microwave work in sealed reaction chambers and totally forgot about the
effect that pressure would have on their reactions.

Microwave heating is especially useful for heating viscous materials where
convection cannot take place (like high polymer melts).  But the chemistry
of such reactions is only dependent on the temperatures achieved.  The fact
that "microwave magic" does not occur can easily be proven by using
different wavelengths of radio frequency energy to do the heating.  For
microwave interaction with a chemical reaction, there would have to be
specific frequencies involved.

I have taken a number of quotes from Gavin Whitaker's site to illustrate
this point.  For those interested in the subject, please read the entire
section on chemistry.  My compliments to Gavin Whitaker.  He has matured
into a good scientist!

        Dr. Barry L. Ornitz     ornitz@dpnet.net

------------------
The following quotes are from:  http://www.ed.ac.uk/~ah05/microwave.html

"The question of whether there is a specific microwave effect which
enhances organic reactions, and which cannot be attributed to superheating,
is still open to debate. Examples of claims for specific activation are
open to criticism in the light of what is now known about microwave induced
superheating in solvents. Adamek and Hajek,31 for example, report
non-thermal activation of organic reactions. By performing reactions at the
same temperature under both conventional and microwave heating, they report
a rate increase with microwave radiation. The rate increase is solvent
dependent, suggesting that superheating may be responsible."

"This is in line with a series of kinetic studies on esterification,35
Diels-Alder, and acid catalyzed isomerisation reactions,36 which conclude
that the kinetics and order of these reactions are unaffected by the method
of heating (microwave or oil bath). "

"The rate enhancements shown in reactions under microwave irradiation are
increased by the effects of pressure on the solvent boiling point by
allowing reactions to be conveniently run at much higher temperatures."

"The pressure within the reaction vessel, and the associated reaction
temperature increases which it allows, play an important role in the rate
increases of the reactions just described and no specific microwave effects
need to the invoked to describe the rate increases."

"Superheating, which may result in boiling points being raised by up to
20°C above their conventional value under microwave irradiation (see Table
2), is widely believed to be responsible for the rate and yield increases
which accompany many liquid phase reactions. "

"In 1992, things started looking bleak for the microwave effect when Mike
Mingos of Imperial College, London, and postgraduate student David Baghurst
showed how microwaves heat solvents above their normal boiling points. Most
chemists now think that this superheating is why reactions run faster.
Water, for example, hits 105°C instead of 100°C before boiling, and
acetonitrile, another popular solvent, gets to 120°C, an amazing 38°C
higher than its usual boiling point. This is because microwaves heat all
the solvent in a flask directly (see "Let's do the twist"), allowing it to
reach a higher than usual temperature before bubbles can form and it boils.
A Bunsen burner, by contrast, heats the edges of a flask where bubbles form
much more readily, so the heat is transferred much more slowly to the
interior. "

"First of all microwave heating is direct - energy is absorbed by the
solely by the sample, and is not wasted on heating the sample vessel.
Direct heating also means that it is a highly controllable form of heating:
lag-times in heating regimes are very small, making rapid changes in
temperature possible. This makes microwave heating highly efficient, and in
many cases, this efficiency will over-ride the fact that microwave energy
is relatively expensive.

The direct nature of microwave heating makes it possible to heat specific
components of a reaction in preference to others - in many cases, it is
possible to focus the energy on specific geometric regions of the sample -
allowing reactions to be performed under highly inhomogeneous conditions."