Solvatochromism,halochromism, and preferential solvation of new dipolar guaiazulenyl 1,4-benzoquinone methides

The synthesis and the solvatochromic properties of five dyes, obtained by condensation of guaiazulene with 4-hydroxybenzaldehydes, are described. Crystal structures of a quinoid dye and a phenolic dye precursor are presented. The dyes are sensitive to the dipolarity-polarizability of the medium and to the hydrogen-bond donor ability of protic solvents. Their solvatochromism is discussed in terms of Kamlet-Taft's pi* and alpha scales, and their difference in behaviour is interpreted. Alkali and alkaline earth metal salts effect halochromism, with one exception due to extreme steric hindrance. Thus, this dye is capable of measuring solvent polarities without sensing the presence of electrolytes. Preferential solvation of the dyes in a series of binary solvent mixtures is explained quantitatively by solvent-exchange models.     

Intracavity Multi-Photon-Absorption and the Quantum Noise Spectrum of Light

The intensity noise spectrum is investigated quantum-mechanically for incident coherent light passing through a resonator which is filled with a k-photon-absorber. For k? 2 the noise of the outgoing light is reduced below the shot noise level the reduction being maximal for frequencies that are small in comparison to the cavity bandwidth. It turns out that the highest possible value of this low-frequency noise reduction is obtained when the resonator losses due to transmission through the outcoupling mirror are 2k – 1 times as large as the k-photon absorption losses. In this case the noise at zero frequency is reduced with respect to the shot noise level by a factor of k/(2k – 1).     

Influence of the topography of zinc coated sheet on the results of electron probe microanalysis

As far as possible, electron probe microanalyses (EPMA) must be carried out on optimally smooth surfaces. When analyzing technical surfaces with a roughness resulting from the rolling or coating process, EPMA results are biased, which has consequences especially when determining element mass layer in the detection limit area. This effect was tested and a corrective process was developed on electrolytically galvanized and hot-dip galvanized steel sheet of varying roughness.     

Photometrische Bestimmung von Bor im Grund- und Oberfl?chenwasser

Zusammenfassung Für Wasseruntersuchungen ist die photometrische Borbestimmung mit Curcumin über den Farbkomplex Rosocyanin geeignet. Es wird ein optimiertes Verfahren beschrieben, welches leistungsfähiger ist als die empfohlenen Standardverfahren. Durch die Extraktion mit 2-Ethyl-1,3-hexandiol in Methylisobutylketon wird Bor von allen störenden Bestandteilen abgetrennt, die im Grundund Oberflächenwasser enthalten sein können. Gegenüber anderen Verfahren ist es auch vorteilhaft, daß der Bor-Curcumin-Komplex unmittelbar im Extrakt gebildet wird. Für die Bestimmung von 1 ppb Bor wurde die relative Standardabweichung zu ±4,3% berechnet, für 100 ppb Bor zu ±1,1%.Es wurden die Borgehalte im Leitungswasser, Mineralwasser und Flußwasser verschiedener Herkunft ermittelt; die Referenzuntersuchungen erfolgten emissionsspektrometrisch mit ICP-Anregung.

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Photometric determination of boron in ground- and surface water

Summary The coloured complex rosocyanin which is formed after reaction with curcumin is suited for the photometric determination of boron in water. An optimised procedure is described, which is superior to the usually applied standard method. Boron is separated from interfering matrix components in ground- and surface water by extraction with 2-ethyl-1,3-hexanediol in methylisobutylketone. Another advantage, in comparison with other methods, is the immediate formation of the curcumin complex in the extraction phase. For the determination of 1 ppb boron the relative standard deviation was calculated to ±4.3%, for 100 ppb to ±1.1%.The boron contents of tap water, mineral water and river water of different origin were investigated; reference measurements were carried out using emission spectrometry with ICP excitation.

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Wir danken Herrn Dr. G. Drews für die Durchführung der Messungen am ICP-Emissionsspektrometer des Römisch-Germanischen Zentralmuseums in Mainz.     

Mapping parameters across system boundaries: parameterized model reduction with low rank variability in dynamics

Linear dynamical systems with an affine parameter dependence producing low-rank variation in the state matrix can be recast as a nonparameterized system operating in parallel with a parameterized feed forward term operating under output constraints. This mapping permits the application of standard (nonparametric) model reduction strategies to solve parameterized problems. We demonstrate the approach on a parameterized vibration problem using optimal tangential interpolation. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Polycarbonate activation for electroless plating by dimethylaminoborane absorption and subsequent nanoparticle deposition

Electroless plating of metal films on polymer substrates usually requires the presence of metal particles acting as catalytically active nuclei for the deposition reaction. Herein, we present a novel and versatile approach towards the activation of polycarbonate substrates with metal nanoparticles. It is based on the diffusion of dimethylaminoborane into the polymer matrix, followed by reaction of the sensitized substrates with metal salt solutions. The reducing agent uptake was controlled by changing the duration of the sensitization and the dimethylaminoborane concentration in the sensitization solution. Different seed types (Ag, Au, Pd, Pt and Rh) were deposited by variation of the activation solution. The proposed mechanism was confirmed with FTIR and TEM measurements. In addition, AFM revealed that apart from a slight roughening in the nanometer range, the surface morphology of the polymer remained unchanged, rendering the method viable for template-based nanomaterial fabrication. Due to its pronounced variability, the new technique allows to tailor the activity of polymer substrates for consecutive electroless plating. The feasibility and nanoscale homogeneity of the process were proven by the electroless fabrication of well-defined Au and Pt nanotubes in ion-track etched polycarbonate templates. The combination of features (use of simple and easily scalable wet-chemical processes, facile seed variation, high activation quality on complex surfaces) renders the outlined technique promising for the fabrication of intricate nanomaterials as well as for the metallization of macroscopic work pieces.