Localization,quantum interference,and the metal-insulator transition

The density of states, and the phase diagram of localization in a three-dimensional disordered tight binding model with box, Gaussian, and Lorentzian distribution of the site energies is numerically determined. The influence of the behaviour of the spectral density on the position of the mobility edge is discussed. Extended states are found outside the unperturbed band for the box and the Gaussian distribution. This implies the existence of two metal-insulator transitions at certain energies which may be attributed to the breakdown of potential localization, and the breakdown of quantum interference localization, respectively. The general validity of the scaling hypothesis in the localization theory is discussed in view of these results.     

Composition dependent phase transformation of Pt0.5−x Mn0.5+x from A1 to L10 phase

Pt_0.5−x Mn_0.5+x films were prepared by sputtering deposition of Pt foil and Mn target to study the order-disorder transition from a thermodynamic metastable fcc (A1) phase to L1₀ phase. Both Differential Scanning Calorimetry and High Temperature X-Ray Diffraction studies showed the phase transformation from fcc to the L1₀ structure for the Pt_0.50Mn_0.50 and Pt_0.40Mn_0.60 samples but along completely different kinetic paths. A composition dependent phase transformation was observed by comprehensive Differential Scanning Calorimetry studies on a series of Pt_0.5−x Mn_0.5+x samples. The changes of the lattice parameter and the cell volume of L1₀ Pt_0.5−x Mn_0.5+x as a function of composition suggest that the anti-site is not the dominant point defect for L1₀ Pt_0.5−x Mn_0.5+x .     

The role of metacognitive monitoring in explaining differences in mathematics achievement

The relationship between practised monitoring activities and performance, especially in mathematics was examined within three nested studies. The first study deals with problems of faulty term rewritings submitted to three groups of subjects—10th to 13th graders, differing in their mathematical performance—whose task was to find the mistakes. Moreover, a questionnaire on the practice and appreciation of monitoring activities was developed. The third study, first, repeats the first study with a similar population and secondly adds interviews with some of the subjects while solving additional items concerning faulty term rewritings. Studies 1 and 3 show similar success in finding mistakes and in the replies to the questionnaire within the various groups. Furthermore, the third study points up that the subject’s answers do neither predict the practised monitoring nor the success in the test. However, the success correlates significantly with the practised monitoring. For a deeper understanding concerning the role of metacognition in explaining performance, the second study examined two of the groups who had already been involved in the first study. These were assigned some problems of a matrices test as used in cognitive psychology. While trying to solve the problem, their eye movements were recorded by means of an eye-tracker. Afterwards they had to justify their solutions in an interview. The eye movements were analysed, the verbal comments classified. Again, the groups differ in their problem solving success, dependant on the quality of the monitoring practised. Altogether, the results of the three studies elucidate the importance of practised metacognitive monitoring activities not only for success in school algebra, but furthermore the ability and the willingness to do it is deeper anchored in a person than just a trained behaviour for school algebra.     

Über den Propylidendipropyläther

Ohne ZusammenfassungSchliesslich ist es mir eine angenehme Pflicht, meinem hochverehrten Lehrer, dem Herrn Prof. A. Lieben für die freundliche Unterstützung, welche er mir bei Ausführung vorliegender Arbeit zu Theil werden liess, meinen aufrichtigsten Dank auszusprechen.     

Ueber die Bestimmung des Gerbstoffs in Gerbstoffmaterialien

Ohne Zusammenfassung     

Fifty Years of Inorganic Biomimetic Chemistry: From the Complexation of Single Metal Cations to Polynuclear Metal Complexes by Multidentate Thiolate Ligands

This article covers 50 years of coordination chemistry of transition metal complexes and metal-sulfur aggregates involving thiolate-incorporating ligands by reviewing selected examples. The studies in the coordination chemistry of sulfur-rich ligands have been undoubtedly triggered and fed by the concomitant development of bioinorganic chemistry, particularly of iron-sulfur enzymes. The review is broken down in five sections, which examine complexes of increasing nuclearity, including binuclear complexes based on compartmental macrocyclic ligands. We show also how ligand engineering has allowed the researchers in the field to control the nuclearity of the complexes, which was a particularly difficult task for sulfur-based ligands, as thiolates show a strong tendency to coordinate to more than one metal cation at once.