Validation by Lachlan M.D. Cranswick E-mail: l.m.d.cranswick@dl.ac.uk Scientific Secretary for the CCP14 Project IUCr Computing Commission Member IUCr Electronic Publishing Committee Member IUCr Teaching Commission Consultant

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Request for comments by JKC (19/11/99)
Hi Lachlan,
If I send you an identifier and password, would you like to have a look at the PD course material - I am after feedback. So far the students have only had one "lecture". I am mainly after comments on the "links" page that I have just created (based on Huub Driessen's PX one).
Jeremy Karl

You may want to also add a link to Armel's SDPD database and Freeware tutorial: http://www.cristal.org/iniref.html

Structure determination by powder diffractometry http://www.cristal.org/iniref/tutorial/indexa.html

If you want to go overboard a bit on Professional Associations
Society of Crystallographers in Australia: http://www.sca.asn.au
Swiss Society of Crystallography http://www-sphys.unil.ch/sgk/soc-sgk.html
Nederlandse Vereniging voor Kristallografie http://krop.chem.uva.nl/nvk/
Belgian National Committee for Crystallography http://www.cpmc.ucl.ac.be/belg_com.html

When referring to www.iucr.ac.uk - this should probably be changed to www.iucr.org

Not sure if by Birkbeck standards - Hugo Rietveld is classed as a Famous Crystallographer or can be put under the Rietveld Mailing list? http://home.wxs.nl/~rietv025/

I don't like to say this but the ICDD site should probably be added: http://www.icdd.com

Possibly also the ICSD on the Web: http://barns.ill.fr/dif/icsd/

And "3D structures of inorganic materials" (good eye candy and good science?) http://barns.ill.fr/dif/3D-crystals/ or http://www.ill.fr/dif/3D-crystals/
Lachlan.
PS: Have been helping Brian Toby with some suggestions - as he is doing a quite a nice web-interface for the NIST Crystal Data system.

He intends to give this away free and am trying to interest the CDS here at Daresbury in this....

The Web is definitely the trend of the future, though the Cambridge database still seems to be writing X applications to work over the Net.

[ACTION by JKC and HPCD (for PX)?]

Comments:

http://pd.cryst.bbk.ac.uk/pd99/powintro/intro3.htm
Before stating "It seems both cruel and kind that crystallite powders should be so ubiquitous in real life"

It might be useful to mention that Powder Diffraction compresses the 3 dimensional information into one dimension making analysis far more difficult as in the single crystal case?

Unless I missed this comment before, this would put the idea of "cruel and kind" in context. Though this is sort of mentioned at:
http://pd.cryst.bbk.ac.uk/pd99/powintro/intro7.htm
But does not seem to be explicitely pointed out(?)

(Bringing up the concept of cruel and kind reminds me of the following web-comic: "I must say Phil, you certainly know how to put the unusual into cruel and unusual." http://metalab.unc.edu/Dave/ar00086.htm)

http://pd.cryst.bbk.ac.uk/pd99/powintro/intro5.htm
Bragg's Law seems to not have it's Greek symbols - you may have to use GIFs to get this to work on all browsers?
n l = 2 d sin q
It is not working on Netscape 4.7 on Windows 95 and Netscape in SGI IRIX 6.5.6
http://pd.cryst.bbk.ac.uk/pd99/powintro/intro6.htm
Type: digrams should be diagrams "two digrams below:"

http://pd.cryst.bbk.ac.uk/pd99/powintro/waveleng.htm
in the E (keV) formula - the divide by bar is made of 3/4 3/4 3/4 symbols instead of ----- or _____.

http://pd.cryst.bbk.ac.uk/pd99/powintro/intro7.htm
microns comes out in the webpage as: mm

I could not seem to log into the MUD at:
http://mud.cryst.bbk.ac.uk:6006/
[COMMENT by JKC: The Web Course and MUD have different usernames and passwords since they are run from different servers.]

If you can not see the following character as a large red Greek alpha, then please let us know:
http://pd.cryst.bbk.ac.uk/pd99/internet/instruct.htm
This does not look like an alpha.
Lachlan.
[ACTION by PB and JKC]

Continuation by JKC (20/11/99)
Hi Lachlan,
I don't want to doubt your comments, but are you really sure that the Greek letters don't show using your PC in Win95? Can you try with IE (3 or >) to see if that shows the Greek letters on your PC. On NT4 PCs here, it all works swimmingly well. The PX course uses gifs for Greek letters, but they have the big disadvantage that they don't scale properly. I have tried NT4 with Netscape 3 + 4 and IE 3 and they work OK without any fixes (even without service packs being installed). I should probably add more on the technical page for the course. One reason for insisting on PC use this year was that I didn't want to have to sort out Unix X-window fixes. (I have to do the same fix for VMS, but it is trivial to do as system.) Thanks again for all the comments - they will keep me busy for a while (and Paul too!).
Jeremy Karl.

Found the problem, in Edit, Preferences, Appearance, Fonts, This was set to "use my default fonts, overriding document- specified fonts. You may want to mention this in your Browser and HTML page http://pd.cryst.bbk.ac.uk/pd99/internet/techn.htm
Lachlan
[ACTION by JKC for 2000/2001]

If you do have time, any more comments on the latest powder diffraction material would be great! (Releases 3,4,5).
....
Have a good time - will write again,
Jeremy Karl Cockcroft.

Put a request into the CDS if the server holding the ICSD database at Daresbury could be left on over Christmas - but alas the answer is no - what can be shut down, is being shut down.

Lachlan.
----
Laboratory Methods feedback - links via: http://pd.cryst.bbk.ac.uk/pd99/pdindex.htm

http://pd.cryst.bbk.ac.uk/pd99/inst1/labintro.htm. Having some photos of the different cameras associated with the page would be nice (with some data they have generated) if this was possible. I see you have pictures of some of the cameras in other pages.

http://pd.cryst.bbk.ac.uk/pd99/inst1/anode.htm. Another practical solution for fluorescence for Copper X-rays is to put a diffracted beam graphite monochromator?

http://pd.cryst.bbk.ac.uk/pd99/inst1/xtube.htm. Mention that ceramic XRD tubes are now being produced which may displace Glass based tubes.
[ACTION/COMMENT by JKC: I do mention ceramic tubes briefly - maybe more emphasis or a picture is required?]

http://pd.cryst.bbk.ac.uk/pd99/inst1/monoc.htm. Could be good to include some photographs of diffracted beam monochromators mounted on some diffractometers. Like the AMR on the Philips Powder Diffractometer at the MSL in Daresbury.
[COMMENT by JKC: One is shown, but on a later page when discussing Bragg-Brentano geometry.]

http://pd.cryst.bbk.ac.uk/pd99/inst1/detects.htm. Not sure if you want to mention that annealed Cubic Y2O3 makes a good calibration standard as well as other specialised (but more expensive options)
[ACTION by JKC for next year.]

http://pd.cryst.bbk.ac.uk/pd99/inst1/samples.htm. Good to mention a McCrone micronising mill where the sample is shaken/pounded by ceramic cylinders in a plastic jar while in a appropriate cooling solution such as ethanol or acetone. Often with little affect on the crystallinity. Can also give a "nice" tight particle distribution.

http://pd.cryst.bbk.ac.uk/pd99/inst1/mounts.htm. When you mention "tiny" amounts being usable with flat plate geometry and silicon low background plates - you might want to mention quantities? 2 to 10 milligram was a value Ian Madsen used to quote. Not sure what your experience is on this.
[ACTION by JKC/MV.]

Also, not sure of you want to elaborate further on air sensitive samples/liquids/slurries. Besides capilliary geometry, 6 micron Mylar over the top can be quite good for this (2 micron can tear very easily - needs more care). Also, 6 Micron polypropylene can be a good complement to the 6 micron Mylar as it gives nasty peaks (compared to mylar) but not where Mylar has the humps. So combining the two patterns can give you a good idea what peaks are present in the phase.

http://pd.cryst.bbk.ac.uk/pd99/inst1/counts.htm. Mentioning that optimised variable count time scans are mentioned in the literature. (Bill David; Rod Hill and Ian Madsen)

http://pd.cryst.bbk.ac.uk/pd99/inst1/texture1.htm. Might want to mention possible ways of getting around preferred orientation with flat place geometry - such as "dusting" and "spray drying". (But for the dusting at least - it can all be hit and miss. spray drying can be inconvenient and you need the equipment)

[ACTION by JKC (many of these comments will be used when the material is next updated, but not for 1999/2000)]

Symmetry:
Will need to read this a few times. Overall, on a first reading this seems to be well explained but would expect most people will have problems grasping this correctly if they have not come across it before.

I get the impression that a "warning" might have to be given at the front - that this is one of the most difficult areas to understand in crystallography - and re-readings and drawing of the concepts on paper is recommended. And perhaps some other hints on "understanding" what they are reading. Possibly in: http://pd.cryst.bbk.ac.uk/pd99/symm1/symintro.htm.
[COMMENT by JKC: This is the object of having the release notes. I presume LMDC forgot to read them in his desire to look at the course material itself.]

When referencing VRML and Gif Animations, as you will guess, I mean for a future version. This version suffers the same as the text books as being a two dimensional medium explaning a 3D concept(?). Not easy to understand by yourself - much easier with a tutor handling wooden blocks?
------
http://pd.cryst.bbk.ac.uk/pd99/symm1/rot6p2.htm. For the pages on interactively rotating a benzene ring. You might like to put a "back" button on all the pages. (it is not that obvious on an 800x600 screen that one of the pages has a back button right at the bottom)
Same goes for the "bar 3" exercise http://pd.cryst.bbk.ac.uk/pd99/symm1/rotinv7.htm.
-----
I like how the Bravais lattice section is explained. (again text books can be quite confusing here) Though unless I missed something, it is not all that clear why Bravais lattices need to be mentioned and in what context they will be used later. Having example "real" crystal structures (maybe in VRML if possible - where you can have text labels and arrows) might make this clearer?)
--------
Screw axis information if presented clearly (unlike those same text books). Mentioning why it can come about (re a molecular crystal) is a nice touch.

http://pd.cryst.bbk.ac.uk/pd99/symm1/screw3.htm. "Four-one (and six-one) and four-three (and six-five) screw axes correspond to right-handed and left-handed helices, respectively."

Possibility for the future. Having some gif animations for the above could make this easier to visualise. Or advising they draw this out for themselves to help get this into their heads.

I also think insisting/suggestion at points they draw this out and just not thinking about it while looking at the screen could be helpful. Otherwise it can be in one ear and out the other. Even though they might think they are getting the "jist" of it without being able to apply it.
[ACTION by JKC - make sure this is tested in an assignment]
--------
http://pd.cryst.bbk.ac.uk/pd99/symm1/glide1.htm. It could be good to have a side by side GIF of a Screw Axis and a glide (as given on this page). I get the impression after reading up to this point, they will be quite confused and initially think this is just a screw axis by another name.
---------
http://pd.cryst.bbk.ac.uk/pd99/symm1/symbols.htm. Symmetry Symbols (while still only reference material) - it would be good to have some VRML or GIF Animations that would possibly gain their interest in such things. My initial reaction to this page ("AARHHG")
[COMMENT by JKC: I certainly agree if this had been presented as learning material, but it was not and the student are told this clearly in the release notes (see my earlier comment on this).]

Problem (as with most crystallographic texts) is trying to describe 3D information going to 2D notation in 2D. VRML (and morphing GIF Animations) could help here. This is the type of thing you like to see a tutor handling wooden blocks while describing(?)
----
Looking back at: http://pd.cryst.bbk.ac.uk/pd99/symm1/trans1.htm. Lattices - more VRML/Gif Animations might help for a future version.
==========

Course: Advanced Certificate in Powder Diffraction on the Web

Reviewer's Name: Lachlan M. D. Cranswick
Address: Daresbury Laboratory, Cheshire, UK.
Relevant affiliations: (see top of this web page)

1. Comments on the accuracy of the course material?
   Course content so reviewed so far is accurate.
2. Comments on whether the course material is up-to-date?
   Course material is up-to-date. Indicative of this is the accuracy of using synchrotron radiation and other cutting edge crystallography techniques. Many conventional texts fail in this regard.
3. Comments on the design of the course material?
   The text and interaction is well designed and optimised for the World Wide Web in comparison with just putting a text book on the web.
4. Comments on the balance of the course material in terms of topics?
   N/A
5. Comments on the quality of the course material?
   Course material so far has been of very good quality. The text is also interesting to read in constrast to common crystallographic text books which are not interested to read.

   Obviously thought has gone into the importance of this for an electronic medium such as the World Wide Web where it is easy for students to be distracted if the material is not clear and interesting to read.

6. Comments on the course work?

   N/A

7. Comments on the projects?

   N/A

8. Comments on the innovative aspects of the course?

   It is obvious from the high quality of the course that much effort has been put into the design and implementation of this course for the Web. Overall it is very well done.

   There may have to be a version 2 of this course, mainly due to the area of Crystallographic SpaceGroups. The text here is superior to average learning material in this regard. But it still falls behind on what could be done with VRML or other 3D technology. Obviously this is very time consuming and intensive task to implement and the present spacegroup text is adequate for the course.

9. Any other comments?

   None.

Lachlan M. D. Cranswick

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