Hi Jianying:

I hope you are doing well and having a nice week so far.  I hate to
 bother you with this question, but depending on whether I will have 
the data to do so, I may be running a principal component analysis 
on some past data from the lab.  I need to speak with Dr. Kleeberger
tomorrow morning so that I can clarify some things, but if possible,
would you possibly be available to meet sometime tomorrow afternoon or 
anytime on Friday so that I can discuss the principal component 
analysis?  I just want to be sure I do it correctly and I would feel 
better knowing I had your expertise.  If you do not have the time, 
though, please do not worry and know that I understand .  
Thank you for your consideration, regardless.

Sincerely,
Heather

Well, I found a very good lecture note from PennState on Principal Component Analysis