Use of imaging plates (IPs) in the gas-phase electron diffraction (GED) experiments on the EG-100 M apparatus. The tetrachloromethane molecule as a test object

The gas-phase electron diffraction (GED) experiment at the Moscow State University was carried out for the first time using imaging plates (IPs). The response of the Fuji BAS-MP IPs calibrated by means of ¹⁴C standard sources was found to be linear in a broad dynamic interval (larger than 10⁴). The GED study of tetrachloromethane was carried out in order to test the applied technique (IP reader FLA7000) and the developed software. The determined structural parameters of the CCl₄ molecule are in excellent agreement with those obtained in experiments with photographic registration.     

Reaction pathway to Cu2ZnSnSe4 formation in CdI2

Journal of Thermal Analysis and Calorimetry - We investigated various possible chemical interactions between individual precursor compounds (ZnSe, SnSe, and CuSe) and CdI2 as a flux material used...     

Republication of: Contributions to the theory of pure gravitational radiation. Exact solutions of the field equations of the general theory of relativity II

This is an English translation of a paper by Pascual Jordan, Juergen Ehlers and Rainer Sachs, first published in 1961 in the proceedings of the Academy of Sciences and Literature in Mainz (Germany). The original paper was part 2 of a five-part series of articles containing the first summary of knowledge about exact solutions of Einstein’s equations found until then. (Parts 1 and 4 of the series have already been reprinted, parts 3 and 5 will be printed as Golden Oldies in near future.) This second paper discusses the geometry of geodesic null congruences, the algebraic classification of the Weyl tensor by spinor methods, and applies these to a study of the propagation of gravitational and electromagnetic radiation. It has been selected by the Editors of General Relativity and Gravitation for republication in the Golden Oldies series of the journal. The republication is accompanied by an editorial note written by Malcolm A. H. MacCallum and Wolfgang Kundt.     

High-Pressure NiAs-Type Modification of FeN

The combination of laser-heated diamond anvil cells and synchrotron Mössbauer source spectroscopy were used to investigate high-temperature high-pressure chemical reactions of iron and iron nitride Fe₂N with nitrogen. At pressures between 10 and 45 GPa, significant magnetic hyperfine splitting indicated compound formation after annealing at 1300 K. Subsequent in situ X-ray diffraction reveals a new modification of FeN with NiAs-type crystal structure, as also rationalized by first-principles total-energy and chemical-bonding studies.     

Applications of the LIF method for the diagnostics of the combustion process of gas-IC-engines

Within the underlying project, the task was to develop methods for optical measurements in a hydrogen-fuelled engine with direct-injection, with the goal of measuring the jet patterns during injection, the stratification of the charge at ignition point and the propagation of the flame during combustion. Therefore, the method of planar laser-induced-fluorescence (PLIF) was chosen. In order to apply this technique for the named tasks, particular methods the visualisation of fuel distribution and the flame front were developed. The measurements were carried out on a single cylinder research engine installed at the Institute for Internal Combustion Engines at Graz University of Technology. This engine features optical access through a quartz-glass liner and a window in the piston while providing a layout equivalent to modern passenger car engines and the possibility to operate in fired mode. As it is hardly feasible to directly excite molecular hydrogen by means of laser light, it is necessary to add a tracer substance to the fuel that provides high fluorescence intensity while not changing the properties of the fuel. Consequently, Triethylamine was chosen as a tracer to be mixed with hydrogen at 200 ppm, which allows it to be used up to a maximum pressure of 200 bar while still providing a strong LIF signal. Due to the excellent linearity of the signal to the local air/fuel-ratio it was possible to develop a method for the calibration of the images in order to compensate for inhomogeneities of the laser beam and staining of the optical access and to ultimately allow a quantification of the fuel distribution. The results are images scaled on air/fuel-ratio which can be used for a direct optimisation of mixture formation processes and the validation of CFD-models. For the analysis of the combustion process the method was adapted with two different approaches. For homogeneous charges a new method was applied by marking the flame front using the tracer within the fuel, so that both are burned together. However, as this method is limited to measurements with a homogeneous distribution of tracer within the measured volume, an alternative technique had to be applied for the measurement of stratified charges. In this case, a direct visualisation of the flame front was achieved by exciting the OH-radicals formed during combustion. As this method has significantly increased demands on measuring equipment and is more time consuming, both methods are used in parallel on specific measuring tasks.     

Effective plastic properties of laminates

In this contribution, we make use of the fact homogenization of elastic properties of laminates [1] can be extended relatively easy to the plastic case [2] to derive exact expressions for the effective yield limit and the ultimate loading in monotonic tension test. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)