Tuesday, March 03, 2009

Effect of the microgravity on the crystallization of self-assembling layered material

En clase de tecnología química , el Dr. Rios nos mencionó que en el congreso de ingeniería química se había presentado una conferencia sobre la cristalización de los fluidos en gravedad cero, ya que no pude ir a tal evento, me dí a la tarea de investigar un poquito acerca de este tema. No existe mucha información confiable en internet, por lo cual me metí al buscador Sci-finder encontrando el artículo con el mismo nombre que el título de este post publicado por la universidades de Illinois y de Toronto, y del cual les dejo una descripción general. Si alguien se interesa por el artículo, me lo puede pedir.

"In microgravity, crystals of semiconductors and proteins can be
grown with improved crystallinity, offering the prospect of
improved structural analyses (for proteins) and better electronic
properties (for semiconductors)1–3. Here we study the effect of a
microgravity environment on the crystallization of a class of
materials—layered microporous tin(IV) sulphides4–11—whose
crystal structure is determined by weak interlayer interactions
(electrostatic, hydrogen-bonding and van der Waals) as well as
strong intralayer covalent bonds.We find that the crystals grown
in microgravity (on board the Space Shuttle Endeavour) show
improved crystal habits, smoother faces, greater crystallinity,
better optical quality and larger void volumes than the materials
grown on Earth. These differences are due at least in part to the
profound influence of microgravity on the layer registry over
length scales of around a nanometre, which is shown by X-ray and
electron diffraction to be better in space than on Earth. Thus we
can see a clear distinction between the covalent bonds in these
materials, which are not significantly affected by microgravity,
and the weaker forces (like those that determine the structure of
proteins over length scales of around 0.3–0.4 nm) which are more
susceptible to the dynamic disturbances that operate in crystallization
on Earth."

saludos

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The "Silver Song"

Este video es obra creativa de Armando Isaac, para el curso de Química Inorgánica I.