Evolution of the interfacial structure of LaAlO3 on SrTiO3

The evolution of the atomic structure of LaAlO_{3} grown on SrTiO_{3} was investigated using surface x-ray diffraction in conjunction with model-independent, phase-retrieval algorithms between two and five monolayers film thickness. A depolarizing buckling is observed between cation and oxygen positions in response to the electric field of polar LaAlO_{3}, which decreases with increasing film thickness. We explain this in terms of competition between elastic strain energy, electrostatic energy, and electronic reconstructions. Based on these structures, the threshold for formation of a two-dimensional electron system at a film thickness of 4 monolayers is quantitatively explained. The findings are also qualitatively reproduced by density-functional-theory calculations.     

Beziehungen der Kolloidchemie zur Physiologie

Ohne ZusammenfassungNach einem Vortrage in der naturwissenschaftlichen Hauptsitzung der 78. Versammlung deutscher Naturforscher und Aerzte in Stuttgart am 20. September 1906     

Beiträge zur allgemeinen Kolloidchemie. VIII

Ohne Zusammenfassung     

Learning with classroom videos: conception and first results of an online teacher-training program

Within the framework of a yearlong teacher education program we examined the conditions and effectiveness of learning with classroom videos. In online phases and face-to-face sessions (blended learning), 20 teachers from two different countries. (Germany and Switzerland) analyzed videos of their own mathlessons and math-lessons of other teachers. Using different instruments, the training program was evaluated from a scientific perspective. The evaluation aimed to obtain information about processes within the training, about the acceptance of the training by the teachers and the patterns of perception of teaching processes of the teachers.     

Influence of boundary conditions on the stability of a column under non-conservative load

The cantilever follower force problem with external damping is extended to a three-parameter case, including a concentrated mass, a linear elastic spring, and a partial follower force at the free end. As a result of the study an unexpected, hitherto unrecognized feature of stability/vibration is identified.Normally, the boundary conditions have great influence on the stability limits. However, it is proved that there exists a force at which the critical frequency is independent of all three boundary parameters. The characteristics of this force/frequency combination are discussed in detail, especially in relation to the corresponding eigenfunctions.Also a direct study of the onset of flutter as a function of the boundary parameters is included.     

Eine neue Schnellmethode zur Analyse von Sulfhydrat- und ?hnlichen Laugen

Schlussbemerkung Für die Beleganalysen, welche die aus den gemachten Beobachtungen gezogenen Schlüsse jeweils voll best?tigten, wurde eine Reihe Laugen aus reinen Chemikalien mit entsprechenden Zus?tzen jeglicher Kombination hergestellt, auch wurden zu bereits untersuchten Handelslaugen entsprechende Zus?tze gemacht und wurde die ?nderung des Analysenbildes festgestellt. Von einer Darlegung der verschiedenen Untersuchungsreihen und Methoden und von einer Aufz?hlung markanter Analysenergebnisse soll im Rahmen dieser kurzen Abhandlung abgesehen werden. Die hier beschriebene Methode gibt bei allen Arten von Sulfhydrat-und ?hnlichen Laugen, gleichgültig ob Natrium, Kalium, Ammonium, Calcium oder dergl. als Base vorliegt, gleich gute und exakte Resultate.