The Impact of the Turing Number on Quantitative ASAXS Measurements of Ternary Alloys

During the last ten years, anomalous small-angle x-ray scattering (ASAXS) became a precise quantitative method resolving scattering contributions two or three orders of magnitude smaller compared with the overall small-angle scattering, which are related to the so-called pure-resonant scattering contribution. The technique gives access to the analysis of weak concentration fluctuations in systems undergoing spinodal decomposition, which cannot be resolved by transmission electron microscopy (TEM) images because these systems are to a large degree homogeneous. In addition to the structural information, precise quantitative information about the different chemical concentrations localized in the nanosized structures of ternary alloys are obtained from these scattering contributions. The application of the Gauss elimination algorithm to the vector equation established by ASAXS measurements at three x-ray energies is demonstrated for two ternary alloys, one in the state of spinodal decomposition. The example deals with the quantitative analysis of the resonant invariant (RI-analysis). From the integrals of the pure-resonant scattering contribution, the chemical concentrations in the nanoscaled phases are determined. Moreover the Turing numbers of the vector equation stated by the ASAXS measurement are calculated giving a decisive quantitative measure thereby indicating whether the quantitative parameters obtained from the matrix inversion are significant.     

Solid-state reactions during high-energy milling of mixed powders

The phase formation of carbides and borides during high-energy ball milling has been investigated by measuring the gas temperature inside the vial and by X-ray diffraction studies of specimens taken at different stages of the milling process. The formation mechanism changes from a gradual process to an instantaneous, explosion-like reaction with increasing milling intensity and enthalpy of product formation. Finally, a model was developed to describe the milling process, and to determine the peak temperatures that are reached in the powder particles during ball collisions as well as the microstructure evolution. Using an effective coefficient of diffusion and calculating the evolution of the continuously growing diffusion layer, it was possible to determine whether and when rapid phase formation occurs. The model was tested by reproducing the milling times needed for rapid phase formation inside the mill.     

Cleanability of Surfaces from Active Pharmaceutical Ingredient Surrogate Riboflavin by Falling Film

Falling films in wash down process are of major interest for pharmaceutical isolators, which are used for processing of highly potent pharmaceutical products. In this study multiple process parameters were examined with common materials of isolator systems. The importance of material and surface finish in respect of cleanability and complete wetting as well as a combination of process parameters are presented and discussed. For cleaning validation an effect of high interest was discovered: swab sampling areas changed their properties over many repeated cycles and showed decreased cleanability.     

Pop-out into memory: A retrieval mechanism that is enhanced with the recall of subject-performed tasks.

Subject-performed tasks (SPTs; i.e., carrying out the actions during study) improve free recall of action phrases without enhancing relational information. By this mechanism, items pop into a person's mind without active search, and this process especially extends the recency effect. The authors demonstrated the existence of the extended recency effect and its importance for the SPT recall advantage (Experiments 1 and 2). Carrying out the action and not semantic processing caused the effect (Experiment 3). The extended recency effect was also not a consequence of a deliberate last-in, first-out strategy (Experiment 4), and performing a difficult secondary task (an arithmetic task) during recall reduced memory performances but did not influence the extended recency effect (Experiment 5). These data support the theory that performing actions during study enhances the efficiency of an automatic pop-out mechanism in free recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oligophenylenevinylenes in Spatially Confined Nanochannels: Monitoring Intermolecular Interactions by UV/Vis and Raman Spectroscopy

Perhydrotriphenylene‐based channel‐forming inclusion compounds (ICs) and thin films made of polyphenylenevinylene (PPV)‐type oligomers with terminal alkoxy groups are investigated and compared in a combined experimental and theoretical approach. Interchromophore interactions and host‐guest interactions are elucidated by UV/Vis and Raman spectroscopy. The impact of the local environment of the chromophore on the optical and photophysical properties is discussed in light of quantum‐chemical calculations. In stark contrast to thin films where preferential side‐by‐side orientation leads to quenching of photoluminescence (PL) via non‐emissive traps, the ICs are found to be attractive materials for opto‐electronic applications: they offer high chromophore concentrations, but at the same time behave as quasi‐isolated entities of tightly packed, well‐oriented objects with high PL quantum yields and the possibility of color tuning.