scholarly journals Random electron diffraction tomography for structure analysis of pharmaceuticals

2017 ◽  
Vol 73 (a2) ◽  
pp. C980-C980
Author(s):  
Stavros Nikolopoulos ◽  
Athanasios S. Galanis ◽  
Oriol Vallcorba ◽  
Alex Eggeman ◽  
Partha Pratim Das ◽  
...  
2014 ◽  
Vol 20 (S3) ◽  
pp. 596-597
Author(s):  
Peter Oleynikov ◽  
Yanhang Ma ◽  
Nobuhisa Fujita ◽  
Javier Garcia-Garcia ◽  
Kyung Byung Yoon ◽  
...  

2014 ◽  
Vol 70 (a1) ◽  
pp. C367-C367
Author(s):  
Tatiana Gorelik

For decades electron crystallography had not been considered as a reliable method of structure analysis, being more a curious scattering experiment. The introduction of electron diffraction tomography brought to light a novel structure analysis technique able to resolve structures of nanocrystalline samples, not assessable by other methods. Electron diffraction tomography is based on the systematically sampling of the reciprocal space by means of electron diffraction. Being in principle very close to single crystal X-ray diffraction experiment, electron diffraction has nevertheless specialities, which make it in a first row an attractive alternative technique, on the other side a demanding experiment and not straight-forward data analysis. The power of electron diffraction tomography method has been clearly demonstrated within the last years – a number of crystalline structures of various material types has been solved. The achievements and potentials of electron diffraction tomography method will be presented, supported by numerous structure analysis examples.


2013 ◽  
Vol 69 (a1) ◽  
pp. s105-s106
Author(s):  
Yanhang Ma ◽  
Peter Oleynikov ◽  
Nobuhisa Fujita ◽  
Francisco Javier García ◽  
Tsutomu Ishimasa ◽  
...  

Author(s):  
Ute Kolb ◽  
Yaşar Krysiak ◽  
Sergi Plana-Ruiz

Electron diffraction tomography (EDT) has gained increasing interest, starting with the development of automated electron diffraction tomography (ADT) which enables the collection of three-dimensional electron diffraction data from nano-sized crystals suitable for ab initio structure analysis. A basic description of the ADT method, nowadays recognized as a reliable and established method, as well as its special features and general applicability to different transmission electron microscopes is provided. In addition, the usability of ADT for crystal structure analysis of single nano-sized crystals with and without special crystallographic features, such as twinning, modulations and disorder is demonstrated.


2018 ◽  
Vol 4 (12) ◽  
pp. eaau6178 ◽  
Author(s):  
Péter Németh ◽  
Enrico Mugnaioli ◽  
Mauro Gemmi ◽  
György Czuppon ◽  
Attila Demény ◽  
...  

Despite its thermodynamical metastability at near-surface conditions, aragonite is widespread in marine and terrestrial sediments. It abundantly forms in living organisms, and its abiotic formation is favored in waters of a Mg2+/Ca2+ratio > 1.5. Here, we provide crystallographic evidence of a nanocrystalline CaCO3polymorph, which precipitates before aragonite in a cave. The new phase, which we term monoclinic aragonite (mAra), is crystallographically related to ordinary, orthorhombic aragonite. Electron diffraction tomography combined with structure determination demonstrates that mAra has a layered aragonite structure, in which some carbonates can be replaced by hydroxyls and up to 10 atomic % of Mg can be incorporated. The diagnostic electron diffraction features of mAra are diffuse scattering and satellite reflections along aragonite {110}. Similar features have previously been reported—although unrecognized—from biogenic aragonite formed in stromatolites, mollusks, and cyanobacteria as well as from synthetic material. We propose that mAra is a widespread crystalline CaCO3that plays a hitherto unrecognized key role in metastable aragonite formation.


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