0000000000046893
AUTHOR
Werner Kraus
Combining EXAFS and XRay Powder Diffraction to Solve Structures Containing Heavy Atoms
Determination of structures using x-ray powder diffraction is complicated if the reflection intensities are mainly influenced by the scattering from heavy atoms and the atomic coordinates of light atoms remain uncertain. A method like EXAFS, which is sensitive to short range order, gives reliable atomic distances in the surroundings of heavy atoms with a precision of ±0.02 A. The probability for obtaining the complete structure from x-ray powder diffraction increases if one includes parameters derived from EXAFS measurements as restraints during the procedure of structure solving. We demonstrate the potential of combining EXAFS and x-ray powder diffraction by solving the structure UO2[H2AsO…
Workshop on performance variations in H? ion sources 2012: PV H?12
This paper briefly summarizes a workshop held in Jyvaskyla the day after NIBS’12. The half-day workshop aimed at globally capturing the issue of performance variations in H− sources. There was a focus on production facilities and facilities that work under production-like conditions, because there are often high expectations to be met.
Identification of hexanuclear Actinide(IV) carboxylates with Thorium, Uranium and Neptunium by EXAFS spectroscopy
International audience; Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with increasing pH. The resulting amorphous and partly crystalline oxydydroxides AnO(n)(OH)(4-2n)center dot xH(2)O can usually be observed as colloids above the An(IV) solubility limit. The aging process of such colloids results in crystalline AnO(2). The presence of carboxylates in the solution prevents the occurrence of such colloids by formation of polynuclear complexes through a competing reaction between hydrolysis and ligation. The majority of recently described carboxylates reveals a hexanuclear core of [An(6)(mu(3)-O)(4)(mu(3)-OH)(4)](12+) terminated by 12 carboxylate l…
Mikroangiographische Untersuchungen verschiedener menschlicher Tumoren nach Transplantation auf thymusaplastische Nacktmäuse
Zehn verschiedene humane Tumoren (zwei Weichteilsarkome, sieben Adenokarzinome des Dickdarms und Magens sowie ein Plattenepithelkarzinom der Lunge) wurden unter die Bauchhaut von thymusaplastischen Nacktmausen implantiert und nach Anwachsen uber mehrere Generationen transplantiert. Bei 40 Tieren wurden die resultierenden Tumoren mikroangiographisch und histologisch untersucht und unter Zugrundelegung der bekannten angiographischen Tumorkriterien klassifiziert. Hierbei fanden sich bei Transplantaten des selben Ursprungstumors immer gleichartige Gefasbilder. Die histologischen Bilder korrelierten gut mit den rontgenologischen Befunden. Die histologische Feinstruktur der Tumorgefase sowie die …