Facile non‐lithographic route to highly aligned silica nanopatterns using unidirectionally aligned polystyrene‐block‐polydimethylsiloxane films

Thin films (monolayer and bilayer) of cylinder forming polystyrene‐block‐polydimethylsiloxane (PS‐b‐PDMS) were shear aligned by the swelling and deswelling of a crosslinked PDMS pad that was physically adhered to the film during solvent vapor annealing. The nanostructures formed by self‐assembly were exposed to ultraviolet‐ozone to partially oxidize the PDMS, followed by calcination in air at 500 °C. In this process, the PS segments were fully decomposed, while the PDMS yielded silica nanostructures. The highly aligned PDMS cylinders were thus deposited as silica nanolines on the silicon substrate. Using a bilayer film, the center‐to‐center distance of these features were effectively halved from 38 to 19 nm. Similarly, by sequential shear‐alignment of two distinct layers, a rhombic array of silica nanolines was fabricated. This methodology provides a facile route to fabricating complex topographically patterned nanostructures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1058–1064     

Temporary attachment of carbohydrates to cyclopeptide templates: a new strategy for single-bead analysis of multivalent neoglycopeptides

Employing a cleavable carbohydrate–peptide linker, a new strategy for single-bead analysis of multivalent cyclic neoglycopeptides based on Edman degradation is described. Edman degradation of glycopeptides is hampered by the acid lability of the glycosidic bond and potential incompatibilities of phenylthiohydantoin (PTH) derivatives of glycosylated amino acids with PTH derivatives of the proteinogenic amino acids. To overcome this problem, carbohydrates are detached from the cyclopeptide templates before single-bead analysis, allowing for micro sequencing under routine conditions. With this strategy, application of multivalent cyclic neoglycopeptides in split-mix libraries with a subsequent screening process becomes possible for the first time.     

Morphological and elemental characterisation with the high-energy ion-nanoprobe LIPSION

This contribution deals with the morphological and elemental characterisation with high-energy (MeV) focused ion beams (in particular protons) with special emphasis on high spatial resolution in the sub-micrometer regime and very low minimum detection limits (sub-ppm) in trace element analysis. The most important methods like particle induced X-ray emission (PIXE), Rutherford backscattering spectrometry (RBS), as well as scanning transmission ion microscopy (STIM) and STIM-tomography will be illustrated by examples from material and life sciences.     

The fluorite-related anion-excess structure of CeN0.222O0.667F1.333: Ordering of defect clusters

This investigation presents the preparation of CeN_0.222O_0.667F_1.333 by a solid-state reaction from a mixture of CeN:CeF₃:CeO₂ = 1:2:1.5 and its structural investigation. The samples were annealed at 900°C in platinum tubes for different times. The basic structure found by powder neutron diffraction is anion-excess fluorite-related. The unit cell is an orthorhombic distortion of the cubic fluorite cell and has the space group Abm2. The lattice constants are a = 577.71(2) pm, B = 572.76(5) pm, and c = 573.32(6) pm. The structure refined by Rietveld analysis shows that [1:0:2]- defect clusters are present. In samples prepared by longer annealing times an ordering of these clusters to larger aggregates, i.e., toward the vernier phases, was observed. This was deduced from full profile analysis without refining a structural model by comparing the instrumental resolution curves of several models.     

Untersuchungen über Radium- und Bariumfällungen unter Anwendung von Thorium X als Indikator

Zusammenfassung Zunächst wird im Zusammenhang mit Messungen der Fällungsgeschwindigkeit von Thorium X in sulfathaltigen Lösungen eine Methode beschrieben, die es gestattet, während der Fällung, und zwar ohne Störung des Fällungsvorganges, diejenigen Mengen von Thorium X zu bestimmen, die sich jeweils zu bestimmten Zeitpunkten noch in Lösung befinden; dabei konnte der Gehalt an Th X mit Hilfe einer Emanationsmethode genau ermittelt werden.Die Versuchsergebnisse, die in Kurven wiedergegeben sind, lassen deutlich erkennen, daß die Fällung von Th X nicht momentan erfolgt, sondern eine gewisse Zeit beansprucht, die von der Konzentration der zugesetzten Sulfat- und Bariumchloridlösung sowie vom Zusatz anderer Fremdionen abhängig ist; es wird jedoch schließlich immer der gleiche Endzustand vollständiger Ausfällung erreicht, wenn mit äquivalenten Mengen gearbeitet wird.Die Annahme, daß die Fällung momentan erfolgt, daß aber das Fällungsprodukt sich im Laufe der Zeit von einem feinkristallinischen Zustand mit großer Emanierfähigkeit in einen grobkristallinen mit geringer Emanationsabgabe umwandelt, konnte durch besondere Experimente widerlegt werden.Schließlich wird noch eine Apparatur zur Messung des Thorongehalts angegeben, die auch für Untersuchungen des Thoriumgehalts von Quellwässern Anwendung finden kann.

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Summary A method has been worked out which makes it possible to determine the rate of precipitation of thorium X in solutions containing sulphate ion. The amount of thorium X is determined rapidly and accurately by the thorium emanation—thoron—evolved under fixed conditions. Determinations have been made every 5 minute during the time following precipitation, and the results are given graphically.They bring forward, very clearly, that the precipitation of thorium X requires a certain length of time, depending on the concentration of the sulphate and barium-chloride solutions used and on the presence of other ions. However, if equivalent quantities of barium- and sulphate ions are used, the same final result is always reached.It might have been supposed that the precipitation takes place instantaneously but that in course of time, the precipitate undergoes changes through recrystallisations and that the emanating power changes accordingly. That hypothesis, however, could be disproved by special experiments.At last an apparatus for measuring the thoron content is given which can also be applied for investigations of the thorium content of source waters.

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Résumé Les auteurs décrivent une méthode qui leur a permis de déterminer la vitesse de précipitation du thorium X en solutions contenant de l'ion sulfurique. Le thorium X est dosé par son émanation — le thoron — sous des conditions fixées, et les dosages peuvent se faire à intervalles régulières pendant le temps que demande la précipitation.Les résultats montrent que la précipitation du thorium X ne se fait point à l'instant, mais demande un certain temps, dépendant de la concentration des solutions de sulfate et de chlorure de baryum ajoutées et aussi de la présence d'ions étrangers.Les auteurs réfutent par leurs expériences la théorie que la précipitation se fait momentanément et que le précipité change peu à peu son état cristallin et par cela même, sa faculté de dégager l'émanation.Enfin les auteurs décrivent un appareil pour les dosages de thoron, qui pourra servir de même pour déterminer la teneur en thorium dans les eaux vives.

     

Spin-resolved photoemission from epitaxial Au layers on Pt(111): Coverage dependence of the bandstructure and evidence of surface resonances

Au/Pt(111) has been studied by spin-, angle- and energy-resolved photoemission with normal incident circularly polarized synchrotron radiation of BESSY and normal photoelectron emission for different Au coverages. The prepared layers were characterized by LEED and Augerelectron spectroscopy and turned out to grow up two dimensional and epitaxially. In the photoemission experiments the development of the 3-dimensional bandstructure in the -direction could be observed. For a coverage of 2.6 layers the highest occupied spin-orbit split bands are located at about 0.6 eV lower binding energy than the corresponding bands for a 3D-Au crystal and show dispersion which is, however, weaker than in a 3D-Au crystal. A 5 layer Au adsorbate was found to have already the same dispersion and energetic location as a Au(111)-crystal. For thick gold layers, which behave in photoemission like Au(111)-crystals, we find structures that cannot be due to direct transitions into a free electron like final band. The coverage dependence and spin polarization of these structures show that some of them are due to surface resonances, while the origin of one strong peak could not yet be explained conclusively. In addition we find strong hybridization and two avoided crossings in the occupied part of the bandstructure.