Tue May 24 09:01:27 EST 1994

> Victor Skita (SKITA at BSAC.UCHC.EDU) wrote:
> : > Hello out there,
> : > I am looking for a calibration-standard (-sample) for
> : > SAXS-messurements. Any comment, any hint will be helpful!
> : > 
> : > Thanks in advance
> : > 
> : > Wolfgang
> : Can I have more information? How far out in recprical space do you plan
> : to measure (ie. how small is the small in small angle)? For example, mica
> : (from NIST) diffracts beautifully at 1/10 A-1 and is "rock" solid. Please
> : send details. (Folks often use lead-sterate, but it must be DRY. The "d"
> : spacing will change with hydration.)
> : Vic.
>   	Try Collagen. Wet Or Dry....

Rat tail tendon collagen diffracts beautifully and can be used as a reliable 
standard in low angle experiments but Handling of the specimens could represent 
a problem. The tendon must be kept wet (or at list hydrated and under a slight 
tension for best results). Under ideal conditions more than one hundred sharp 
reflections can be obtained on the meridional axis. The first order is 
detectable at 670 Angstroms and 25 orders can easily be detected. This system 
can also be used also at 3 or more meters specimen to detector distance. 
Mishandling of the specimen can generate a number of artifact such as dublets. 
Keep also in mind that this is a biological sample and that could be degraded
if  enzyme inhibitors and a little amount of Sodium Azide (0.02 %) is not added
to  the bathing solution.

Mario Volpi                              Phone:   (203) 679-3892
Biomolecular Structure Analysis Center   FAX:     (203) 679-1989
University of Connecticut Health Center  E-Mail:  VOLPI at BSAC.UCHC.EDU
263 Farmington Avenue                             
Farmington, CT 06030-2017                         

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