Generalized Ostrowski–Grüss-type Inequalities

The paper is devoted to inequalities of Ostrowski–Grüss type. The upper bounds of our inequalities involve least concave majorants of the first order moduli of continuity or differences of upper and lower bounds of first order derivatives. Several inequalities available in the literature are generalized, improved or modified.     

Structural and optical properties of ZnO thin films deposited onto ITO/glass substrates

ZnO films were prepared by post deposition thermal oxidation in the ambient atmosphere of metallic Zn films (d = 100–170 nm) vacuum evaporated onto unheated indium tin oxide (ITO)-coated glass substrates. To study the effect of the substrate position during the Zn film deposition on the microstructure and optical properties (transmittance, reflectance and absorbance) of as obtained ZnO films, two set of Zn samples simultaneously deposited onto horizontally and obliquely arranged substrates were prepared. The as obtained ZnO films had a polycrystalline wurtzite structure, those obtained from normally deposited Zn films having a higher c-axis preferred orientation and a lower optical transmittance in the visible wavelength range. The optical band-gap was found to be of 3.14 eV for oxidized normally deposited virgin Zn films and of 3.16 eV for those obliquely deposited.     

Perfect and locally perfect colorings

We present a new algorithm for coloring perfect graphs and use it to color the parity orderable graphs, a class which strictly contains parity graphs. Also, we modify this algorithm to obtain an O(m² + n) locally perfect coloring algorithm for parity graphs. © 1995 John Wiley & Sons, Inc.     

Bestimmung von Kohlenmonoxidspuren in Sauerstoff

Zusammenfassung Es wurden CO-Bestimmungen an Gasgemischen mit reinem Sauerstoff bzw. Luft durch Reaktion mit einer alkalischen Lösung der Silberverbindung von p-Sulfamidbenzoesäure ausgeführt. Die Reduktion des Reagens durch Kohlenmonoxid zu einem gelb bis graubraun gefärbten Silbersol wird durch reinen Sauerstoff nicht beeinflußt. Unter den gegebenen Bedingungen eignet sich die Reaktion gut zur Bestimmung von Kohlenmonoxidspuren in Sauerstoff bis zu Konzentrationen um 10 ppm.

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Summary CO determinations have been carried out in gaseous mixtures with pure air, by reaction with an alkaline solution of the silver compound of p-sulphamylbenzoic acid. The reduction of this reagent by CO to a yellow to greyish-brown silver sol is not affected by oxygen. Under the given conditions the reaction can satisfactorily be employed in the determination of traces of CO in oxygen up to concentrations of about 10 ppm.

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Herrn Dipl.-Ing. G. Krall sei an dieser Stelle für seine liebenswürdige Mithilfe bei der Übersetzung dieser Arbeit unser Dank ausgesprochen.     

The analysis of conductive solid samples by r.f. capacitively coupled plasma at atmospheric pressure

A radiofrequency capacitively coupled plasma (rf CCP) with tip-ring electrode geometry has been used for the analysis of Al, Co, Cr, Cu, Mn, Mo, Ni, and V in low and medium alloyed steel. The sample is used as one of the electrodes of the plasma torch. The influence of plasma power, argon flow rate and distance between the electrodes on the analytical signals has been studied. The limits of detection are in the range of 0.001 to 0.048%. The dynamic range is three orders of magnitude.     

Analytical performance of an r.f. capacitively coupled plasma for atomic emission with tip-ring electrode geometry

A low to medium power radiofrequency capacitively coupled plasma is characterized as spectral source for atomic emission. The signal to background ratio and the limits of detection were determined for 19 elements as a function of the plasma torch geometry and the observation point.     

Chelate polymers. VI. New copolymers of the some siloxane containing bis(2,4-dihydroxybenzaldehyd-imine)Me with bis(p-carboxyphenyl)diphenylsilane

New high complex polymeric structures containing metal chelate sequences alternating, through esteric bridges, with silane units were obtained. The azomethine of 2,4-dihydroxybenzaldehyde with 1,3-bis(aminopropyl)tetramethyldisiloxane has been synthesized and in situ complexed with copper (II), nickel (II), cobalt (II) and cadmium (II). The obtained bis-phenolic chelates were covalently inserted in polymeric linear structures by their polycondensation with bis(p-carboxyphenyl)diphenylsilane as a diacid chloride. The structures of the obtained polymers were confirmed by IR, UV, ¹H NMR and elemental analysis. The characterization was made by TGA, DSC, solubility tests and GPC. The electrical conductivity of both chelate monomers and their polymers was investigated, all compounds showing typical semiconducting behaviors.     

DNA imaged on a HOPG electrode surface by AFM with controlled potential

Single-molecule AFM imaging of single-stranded and double-stranded DNA molecules self-assembled from solution onto a HOPG electrode surface is reported. The interaction of DNA with the hydrophobic surface induced DNA aggregation, overlapping, intra- and intermolecular interactions. Controlling the electrode potential and using the phase images as a control method, to confirm the correct topographical characterization, offers the possibility to enlarge the capability of AFM imaging of DNA immobilized onto conducting substrates, such as HOPG. The application of a potential of +300 mV (versus AgQRE) to the HOPG enhanced the robustness and stability of the adsorbed DNA molecules, increasing the electrostatic interaction between the positively charged electrode surface and the negatively charged DNA sugar-phosphate backbone.