Re: [ccp4bb] question about powder diffraction

2014-07-09 Thread Kianoush Sadre-Bazzaz
interference is destructive and adds up to nothing. At least that's how I understand it, eab On 07/08/2014 03:53 PM, Kianoush Sadre-Bazzaz wrote: Hi If a sample of powder crystal (say Nickel) is shot with monochromatic x-rays, one will observe reflections from planes that satisfy

[ccp4bb] question about powder diffraction

2014-07-08 Thread Kianoush Sadre-Bazzaz
Hi If a sample of powder crystal (say Nickel) is shot with monochromatic x-rays, one will observe reflections from planes that satisfy Bragg's Law. For Ni the first four planes are (111, 200, 202, 311) with 2theta (44, 52, 76, 93 degrees) respectively. Why doesn't one observe a reflection

Re: [ccp4bb] Low resolution structure determination advice

2011-09-01 Thread Kianoush Sadre-Bazzaz
Hi Basu, You mentioned molecular replacement was not successful for this project. Which model was used for this procedure? Have you tried your partially built structure as a model to obtain preliminary phases for your native (2.7A) data set? If there is  any luck with that, you might be able to

Re: [ccp4bb] curved cylindrical helices in PyMOL?

2009-08-27 Thread Kianoush Sadre-Bazzaz
Hi Susanne, On the Pymol menu go to Setting -- Cartoon --  Cylindrical Helices Kianoush --- On Thu, 8/27/09, Susanne Ressl susanne.re...@mpibp-frankfurt.mpg.de wrote: From: Susanne Ressl susanne.re...@mpibp-frankfurt.mpg.de Subject: [ccp4bb] curved cylindrical helices in PyMOL? To:

[ccp4bb] Merging datasets

2007-08-07 Thread Kianoush Sadre-Bazzaz
Dear CCP4, I have a couple of datasets native and heavy-atom-derivatized. The spacegroup and cell dimensions of all are the same (or very similar). For some reason I cannot merge any of the datasets together. If for example I rescale one native dataset by itself, my Rmerge is about 10%,