Inhomogeneous fluids of colloidal hard dumbbells: fundamental measure theory and Monte Carlo simulations

Recently, a density functional theory for hard particles with shape anisotropy was developed, the extended deconvolution fundamental measure theory (edFMT). We apply edFMT to hard dumbbells, arguably the simplest non-convex shape and readily available experimentally in the form of colloids. We obtain good agreement between edFMT and Monte Carlo simulations for fluids of dumbbells in a slit and for the same system under gravity. This indicates that edFMT can be successfully applied to nearly all colloidal shapes, not just for the convex shapes for which edFMT was originally derived. A theory, such as edFMT, that allows a fast and general way of mapping the phase behavior of anisotropic colloids, can act as a useful guide for the design of colloidal shapes for various applications.     

Single‐crystal diffraction at the Extreme Conditions beamline P02.2: procedure for collecting and analyzing high‐pressure single‐crystal data

Fast detectors employed at third‐generation synchrotrons have reduced collection times significantly and require the optimization of commercial as well as customized software packages for data reduction and analysis. In this paper a procedure to collect, process and analyze single‐crystal data sets collected at high pressure at the Extreme Conditions beamline (P02.2) at PETRA III, DESY, is presented. A new data image format called `Esperanto' is introduced that is supported by the commercial software package CrysAlis^Pro (Agilent Technologies UK Ltd). The new format acts as a vehicle to transform the most common area‐detector data formats via a translator software. Such a conversion tool has been developed and converts tiff data collected on a Perkin Elmer detector, as well as data collected on a MAR345/555, to be imported into the CrysAlis^Pro software. In order to demonstrate the validity of the new approach, a complete structure refinement of boron‐mullite (Al₅BO₉) collected at a pressure of 19.4 (2) GPa is presented. Details pertaining to the data collections and refinements of B‐mullite are presented.     

Development of Na+-sensitive membranes based on sputtered Na-Al-Si glasses

Na⁺-sensitive microdevices are of increasing interest for integration in microanalytical systems e.g. for biomedical applications or for industrial process control. In order to produce ultra thin Na⁺-sensitive layers with fixed and reproducible composition and, in particular, defined Na concentration by means of RF sputtering, an off-axis geometry of a magnetron with cylindrical target was chosen for minimizing back-sputtering effects from the already deposited material. With this inverted cylindrical magnetron (ICM) it was possible to obtain reproducible and controllable sodium aluminosilicate glass layers on semiconductor substrates. Several surface and thin layer analytical techniques were applied for characterization of the membranes and for stoichiometry control. Especially by the non-destructive nuclear reaction analysis method a constant Na profile throughout the glass layer and — together with AES depth profiles — the diffusion barrier effect of an Si₃N₄ interface layer could be verified. Electrochemical measurements proved Nernstian sensitivity down to 10^–4 M Na⁺ in solutions of pH 7, supporting sufficient stability and reproducibility of the sputtered Na⁺-sensitive layers.     

Zur Elektronenstruktur metallorganischer Komplexe der f‐Elemente. 65 Erstmalige Beobachtung des linearen Dichroismus bei einem homoleptischen metallorganischen π‐Komplex der f‐Elemente: Tris(η5‐tetramethylcyclopenta‐dienyl)neodym(III)

Electronic Structures of Organometallic Complexes of f Elements. 65 First Observation of Linear Dichroism of a Homoleptic Organometallic π Complex of f Elements: Tris(η⁵‐tetramethylcyclopentadienyl)neodymium(III) The absorption spectrum of a powder sample of pseudo (Ψ) trigonal planar Nd(η⁵‐C₅Me₄H)₃ ( 1 ) has been measured at room temperature and ca. 40 K, respectively, and the linear dichroism spectra of σ‐ and π‐type of an oriented single crystal at ambient temperature and 77 K. Neglecting the signals of the C–H combination vibrations and overtones extracted from the absorption spectrum of La(η⁵‐C₅Me₄H)₃ ( 2 ), the observed polarization properties of the remaining f‐f transitions allowed the derivation of a truncated crystal field splitting pattern. The free parameters of a phenomenological Hamiltonian were fitted to this pattern leading to a reduced r.m.s. deviation of 16.1 cm^?1 for 38 assignments. The temperature dependence of the paramagnetic susceptibility of 1 was calculated, making use of the crystal field energies and wavefunctions of the fit. Introducing an orbital reduction factor of 0.98, calculated values of 1 agree well with the experimental ones of Ψ trigonal planar Nd(C₅H₄tBu)₃.     

Automation in und mit der Analytischen Chemie IV

Zusammenfassung Es werden die Begriffe Signal (physikalischer Sachverhalt), Nachricht (Signalfolge), Information (entschlüsselte Signalfolge) und die Aspekte der Semeiotik (Lehre von den Sprachen allgemein), der Syntax (Beziehung zwischen den Zeichen), der Semantik (Beziehung zwischen Zeichen und Mensch) für die Automation in und mit der analytischen Chemie beschrieben. Das Morsen ist unter anderem ein Beispiel, an dem die Begriffe Signal, Nachricht und Information behandelt werden. Nach einer Betrachtung der Signalerzeugung wird der Informationsgehalt von folgenden Analysenverfahren diskutiert: RFA mit energiedispersivem Detektorsystem, ein Trennungsgang und die Tüpfelanalyse.

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Automation in and with analytical chemistry. IVMeaning of semeiotics and information content in automatic analysis

The terms signal (physical statement), message (sequence of signals), information (decoded sequence of signals) and the aspects of semeiotics (theory of languages generally), syntax (relation between the signs) and semantics (relation between signs and man) are described. Among others the Morse code is an example for discussing the terms signal, message and information. After considering the production of signals the information content of the following analytical procedures is discussed: X-ray fluorescence analysis with energy dispersive detector system, a classical separation procedure and spot test analysis.

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Teil III: diese Z.247, 1 (1969).     

FTIR-Microscopic investigations of micro-phases and micro-phase-transitions in organic substances

From visual inspection by light microscopy it is likely that structural modifications are coexisting in microdomains of e.g.a-oxofuran acetamide, salicylic acid hydrazide and benzotriazole-5-carbonic acid methyl ester. An isolation of these phases is, however, not easy and a direct analysisin situ requires a non-destructive method of molecular specific microanalysis. Using FTIR-microscopy the samples prepared as thin film by cooling from the molten stage on an Al-mirror could be characterized as heterogeneous (lateral resolution 20m). The IR-spectra of the different microphases could be recorded for the first timein situ. Any conventional sample preparation technique (KBr-disk or dissolution) would destroy the important information about the microphase composition. A mere comparison of the micro-FTIR-spectra shows clearly the difference between the microphases. By using step scanning and image processing devices also invisible microphases can be detected (FTIR-microprobe). FTIR-microscopy can be successfully used to investigate temperatureinduced microphase transitions. Examples for D,L-norleucine, oxeladin citrate and 2-chloro-ethane-amine hydrochloride are given also.     

Rationales und irrationales zur frage: Was ist analytische chemie?

To clarify the position of analytical chemistry in science, some philosophical views are quoted and brief definitions proposed.     

Experimentelle Untersuchung über die Viskosität von lufthaltigem Schmieröl

Zusammenfassung Bei Durchlaufschmierung von Gleitlagern ist das von der Pumpe geförderte und den Lagern zugeführte Öl häufig mit Luftbläschen durchsetzt. Für das Betriebsverhallten von derart geschmierten Lagern ist der Einfluss de Luftgehaltes auf die dynamische Viskosität des Gemisches wesentlich. In der vorliegenden Arbeit wird dieser Einfluss für ein gebräuchliches Turbomaschinen-Schmieröl an der laminaren Strömung in einem Kreisrohr theoretisch und experimentell untersucht. Es zeigte sich, dass bei tiefer Temperatur die Zähigkeit durch die Luftbeimischung reduziert und bei hoher Temperatur erhöht wird.

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Summary The lubricating oil for hydrodynamic bearings supplied by a pump is often containing air in the form of tiny bubbles. Thus the bearings are lubricated with an oil/air-mixture instead of pure oil. The performance of such bearings depends on the influence of the air contents on the dynamic viscosity of the oil/air-mixture. It is the purpose of this paper to determine this influence through a theoretical and experimental investigation, examining an average lubricating oil for turbomachinery at laminar flow in a circular tube. It was found that at low temperatures the viscosity is reduced by the addition of air in the oil, while with higher temperatures the viscosity is increased. By introducing a dimensionless characteristic number for the flow of the oil with air bubbles, the results of the investigation can be given in dimensionless form.