These slides were prepared by Philip Moriarty to address comments made by "Unregistered" in the discussion thread of our article here: https://pubpeer.com/publications/B02C5ED24DB280ABD0FCC59B872D04
I hope the discussion taking place there and in other places will indeed reach a clear conclusion. The slides are here to help.
This issue is important because of the implications for the field of nanoparticles research, but also, more broadly, because of the various issues that this scientific controversy raises in terms of the difficulty of correcting the scientific record (http://raphazlab.wordpress.com/2013/11/27/the-stripy-controversy-as-a-window-into-the-scientific-process/), limitations of traditional peer review, good scientific practices (cherry picking, data sharing, data reuse, etc), etc.
Our article (Stirling et al above) and its predecessor (Cesbron et al,http://raphazlab.wordpress.com/2012/11/23/stripy-nanoparticles-revisited/) are effectively questioning the validity of (at least) the following 31 articles that have collectively been cited over 1500 times:
1. Nature Materials 2004, 3, 330
2. Journal of the American Chemical Society 2006, 128, 11135
3. Small 2007, 3, 814
4. Science 2007, 315, 358
5. Physical Review Letters 2007, 99,
6. Journal of the American Chemical Society 2008, 130, 798
7. Proceedings of the National Academy of Sciences of the United States of America 2008, 105, 9886
8. Advanced Materials 2008, 20, 4243
9. Journal of Physical Chemistry C 2008, 112, 6279
10. Chemical Communications 2008, 196
11. Nature Materials 2008, 7, 588
12. Nature Materials 2009, 8, 837
13. Journal of the American Chemical Society 2009, 131, 16377
14. Angewandte Chemie-International Edition 2011, 50, 7900
15. Journal of the American Chemical Society 2011, 133, 1438
16. Angewandte Chemie-International Edition 2011, 50, 12312
17. Acs Nano 2011, 5, 2587
18. Small 2011, 7, 1961
19. Nanoscale 2011, 3, 3244
20. Biointerphases 2012, 7,
21. Nature Materials 2012, 11, 978
22. Advanced Materials 2012, 24, 3857
23. Nature Communications 2012, 3,
24. Small 2012, 8, 3720
25. Langmuir 2013, 29, 13723
26. Acs Nano 2013, 7, 932
27. Langmuir : the ACS journal of surfaces and colloids 2013, 29, 11560
28. Nanoscale 2013, 5, 6928
29. Chemical Science 2013, 4, 928
30. Acs Nano 2013, 7, 8529
31. Nano letters 2013, 13, 4060
1. White circle: Same particle as identified in Fig. 4 of “Response to “Stripy Nanoparticles Revisited””, Yu
and Stellacci (Small 2012) and argued to provide evidence of stripe formation. Two separate scans of
the same particle are shown. Only the scan on the right was included in Yu and Stellacci’s response.
I have selected the same sample area as used in Fig. 4 of Yu and Stellacci. These are 70 x 70 pixel
‘zooms’ which have been interpolated up to 256 x 256 pixels. A very similar type of interpolation has
apparently been carried out for Fig. 4 of Yu and Stellacci. This acts in a similar manner to a low pass
filter, building in spurious spatial correlations.
In any case, it is absolutely clear from the images above that the “stripes” seen in the STM data are
nothing more than an artefact – in essence, filtered noise. What is perhaps more worrying is that the
image on the right was selected to provide ‘evidence’ for the stripes while the image on the left, which
shows no stripes, was selectively ignored in the Yu and Stellacci response to the “Stripy Nanoparticles
Revisited” paper.
2. This is the uninterpolated (i.e. ~ 70 x 70 pixel)
image from which the interpolated
image on the right hand side of the previous
slide was derived by Yu and Stellacci.
3. Let’s now take a look at an STM image of a sample
of completely unfunctionalised particles which was
prepared as described in “Critical assessment of the
evidence for striped nanoparticles”, Stirling et al.,
http://arxiv.org/abs/1312.6812v1 ...
5. Here’s a contrastsaturated
but uninterpolated
zoom of that area of
entirely ligand-free
nanoparticles .
Note pixellation of
particles and the
statistical
“alignment” of pixels.
Compare with
uninterpolated image
from Yu and Stellacci
(Small, 2012), shown
on Slide #2
Let’s zoom in on that
bottom left corner…
6. Now we interpolate
up to a higher pixel
density and contrast
adjust again.
Let’s focus on the
particles with the
lines drawn on top
(to, ahem, “guide the
eye”) and compare to
the figures in Yu and
Stellacci, Small 2012.
We’ll come back to
the other particle
soon.
7. Direct comparison of
highly interpolated
images of
unfunctionalised
nanoparticles with
images purportedly
showing stripes from
Yu and Stellacci, Small
2012.
The ‘stripes’ are
nothing more than
interpolated noise. As
few as three pixels in
the raw data have
been interpreted as
“stripes” by Yu and
Stellacci.
8. Another comparison of our image of
unfunctionalised particles with the ‘striped’
particles of Stellacci et al…
9. Images in column on left taken from Fig. 1 of
Centrone et al., Small 3 814 (2007).. Top image
shows “standard” particle – no stripes; bottom
image shows multi-ligand-terminated particles
with stripes.
Image directly below is an image of entirely
unfunctionalised particles, prepared as described
in Stirling et al. http://arxiv.org/abs/1312.6812v1 .
Cartoon included as a guide to the eye.
11. Image on the left above is a zoom of the unfunctionalised
particle which is circled on Slide # 6.
Image on the right is a crop from Fig. 6(d) of Jackson et al.,
Nature Materials 3 330 (2004). The full image from
Jackson et al. is shown to the right.
