Search results for "Mechanical engineering"
showing 10 items of 4245 documents
Inhibitoren der Korrosion 24 (1) - Zur Vergleichbarkeit der Abhängigkeit der Korrosion und Korrosionsinhibierung von der Chloridionen- und Inhibitork…
1979
Die Abhangigkeit der „unter Standardbedingungen” im Schuttelversuch ohne und mit Inhibitoren ermittelten O2-Aufnahmegeschwindigkeit von der Chloridionenkonzentration und der Menge an Eisenpulver wird ermittelt. Ergebnis: die von uns bisher eingehaltenen Standardbedingungen vermitteln an Hand der Schutz werte ein qualitativ verlasliches Bild uber die Inhibitorwirksamkeit. Die Vergleichbarkeit der im Schuttelversuch mit DAB 6-Eisenpulver ermittelten Werte mit den im Schuttelversuch mit 1405-Stahlblechen gefundenen Werten wird durch Versuche mit 1405-Stahlblechraspel abgesichert. Die Korrosionsrate phosphatisierter Stahlbleche 1405 wird durch Inhibitoren mit Phosphonsauregruppen wirksam unterd…
Crystal structures of R2Pd2Pb (R = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu) compounds
2004
Abstract The crystal structures of the R2Pd2Pb (R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu) compounds were determined using X-ray powder diffraction. The investigated compounds crystallize with Mo2FeB2 structure type (space group P4/mbm, Pearson code tP10). The importance of stabilization by polar intermetallic R–Pd bonding is underscored by a bonding analysis derived from electronic band structure calculations.
Computer simulations of electron paramagnetic resonance spectra of P2O5Li2WO4Li2O glasses
1992
Abstract P2O5Li2WO4Li2O glasses have been synthesized and studied over a wide range of compositions. The glasses were characterized mainly by thermodifferential analysis and electron paramagnetic resonance (EPR). The EPR spectra are characterized by the presence of two signals with very different intensities, associated with the Wv (major signal) and Mov (minor signal) paramagnetic centres. The signals have been satisfactorily reproduced by computer simulation, assuming anisotropy in the g values as well as the hyperfine parameters and linewidths. EPR parameters have been extracted and indicate metallic ions located in environments close to square pyramidal.
Determination of the first ionization potential of nine actinide elements by resonance ionization mass spectroscopy (RIMS)
1998
The high sensitivity of RIMS enables the precise determination of the first ionization potential of actinide elements with a sample size of ≤1012 atoms. By multiple resonant laser excitation, the actinide atoms under investigation are ionized in the presence of an electric field, and the ions are mass-selectively detected in a time-of-flight spectrometer. The first ionization potential is obtained by scanning the wavelength of the laser used for the last excitation step across the ionization threshold Wth—indicated by a sudden increase of the ion count rate—at various electric field strengths. Extrapolation of Wth to electric field strength zero leads directly to the first ionization potent…
Über die Inhibitoren der Korrosion IV(1). Versuche zur Unterdrückung der Auflösung von Aluminium durch organische Substanzen in saurer und alkalische…
1965
Oniumsalze oder potentielle Oniumsalze sind wirksame Inhibitoren der Auflosung von Aluminium in Salzsaure. Ihr Schutz ist im alkalischen Medium geringer. Corrosion Inhibitors IV. Investigations into the suppression of the dissolution of aluminium by organic substances in acid and alkaline solution Onium salts or potential onium salts are effective inhibitors in respect of the dissolution of aluminium in hydrochloric acid. In the alkaline medium, the protective effect is less marked.
Donor-acceptor substituted polyenes : orientation in mono- and multilayers
1992
Large molecules containing different chemical units whose interactions within the molecule result in new macroscopically observable effects, have become increasingly important.The organization of molecules of this type in ordered structures leads to functional molecular materials.Their use in molecular electronics requires that the units exhibit specific electronic properties. Recently, we reported on the intramolecular energy transfer through terminally substituted conjugated polyenes. An intramolecular electron transfer within donor-acceptor substituted polyenes can be achieved by introducing suitable terminal groups.
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Structure, energy and charge transport in two-dimensional crystals of cyanine dyes
1993
Abstract In order to develop systems with controlled energy or charge transfer across molecular dimensions it is highly desirable to build two-dimensional crystals of functional dye molecules: they can be addressed from the third dimension and the lateral intermolecular interactions can be well characterized due to a fixed and defined geometry. In an effort to study these possibilities we prepared crystals of different, negatively charged cyanine dyes, formed after adsorption from a water subphase to a positively charged monolayer. These crystals are one monolayer thick, of uniform dimensions between 10 and 100 μm (depending on nucleation conditions) and of rectangular shape. Single crystal…
New binary antimonide Hf5Sb3
1999
Abstract Hf5Sb3 can be prepared by arc-melting of hafnium and previously synthesized HfSb2. It crystallizes like the high-temperature modification of Zr5Sb3 in the Y5Bi3 structure type, space group Pnma, Z=4, a=740.75(9) pm, b=871.8(1) pm, c=1073.6(1) pm, V=693.3(1) 106pm3. An antimonide analogous to the low-temperature form of Zr5Sb3 was not obtained during our investigations. In the structure of Hf5Sb3, the Hf atoms form a three-dimensional network with numerous short Hf–Hf contacts, including the Sb atoms in severely distorted two- and three-capped trigonal prismatic voids. Calculations of the electronic structure, performed with the extended Huckel approximation as well as the TB-LMTO-A…
Spray Atomization Models in Engine Applications, from Correlations to Direct Numerical Simulations
2011
Sprays are among the very main factors of mixture formation and combustion quality in almost every (IC) engine. They are of great importance in pollutant formation and energy efficiency although adequate modeling is still on development. For many applications, validation and calibration of models are still an open question. Therefore, we present an overview of existing models and propose some trends of improvement. Models are classified in zero dimensional and dimensional classes ranging from simple formulations aimed at close-to-real-time applications to complete detailed description of early atomization stages.