Microstructural Evolution of Alumina Layers on an Al–Cu–Fe Quasicrystal during High-Temperature Oxidation

The oxidation of a quasicrystal with the nominal compositionAl₆₃Cu₂₅Fe₁₂ was studied around 800°Cin environmental and synthetic air by means of thermogravimetric analysis,electron microscopy, and analytical electron spectroscopy. In an earlyoxidation stage, -Al₂O₃ formed with an orientational relationship tothe quasicrystal. At the oxide–metal interface, -Al₂O₃transformed into large hexagonal shaped -Al₂O₃grains. The change in surface morphology indicated that at theoxide–gas interface -Al₂O₃ continued togrow as -Al₂O₃. Locally the metastable aluminalayer was transformed thoroughly into -Al₂O₃,which then continued to grow with a nodular morphology. On top of the oxidenodules, several at.% of Cu²⁺ were detected.     

Prospective memory failures as an unexplored threat to patient safety: results from a pilot study using patient simulators to investigate the missed execution of intentions

This study investigated failures of prospective memory (PM) as a relevant but neglected error type in medicine. A patient simulator was used to investigate PM failures. The influence of subjective importance (high, low) and type of intention (educational, internal, external) on the (missed) execution of intention was investigated in a 2 x 2 design. The effects on missed executions by importance (high < low) and type of intention (educational < external < internal) were hypothesized. Of 73 valid intentions in 40 prepared simulator scenarios 19 (26%) were missed overall. A total of 64% of unimportant and 80% of important intentions were executed 79% of educational 67% of external and 72% of internal intentions were executed. Neither difference was statistically significant using chi(2) tests. Interaction was significant for missed executions (p = 0.025; n = 19; df = 2; chi(2) = 7.41) and for executions (p = 0.002; n = 54; df = 2; chi(2) = 12.50). Despite low statistical support and some methodological limitations, it was possible to show that PM failures are relevant to patient safety and that patient simulators are a suitable but so far unused tool for their investigation.     

Dufour Gland Contents of Ants of the Cataglyphis bicolor Group

The species of desert-dwelling ants of the Cataglyphis bicolor (Hymenoptera: Formicidae) group are difficult to distinguish by morphological features. Analysis of the secretion from the Dufour glands of workers of a number of colonies was undertaken to see if it provided a clear test of species. Linked 6c-ms showed in all samples straight and branched-chain alkanes, linear alkenes, ketones, aldehydes, acetates, and a group of C₂₂ to C₂₈ esters not previously identified in this genus. Contents of the Dufour glands of C. savignyi from Tunisia and Egypt were similar, and comprised straight and branched-chain alkanes, alkenes and small amounts of esters. C. bicolor from Tunisia contained compounds similar to C. savignyi but was distinguished from the latter by larger amounts of the esters. The major compound in the glands of C. viaticus was tridecane, in contrast to the pentadecane of other species. It also contained a branched alkane, 3-methyltridecane as a major component. Branched-chain esters and a wide variety of acetates were also found in this species. C. diehlii had a limited range of compounds, with branched alkanes almost completely absent and high proportions of pentadecene and dodecyl acetate. C. bombycinus, a sympatric species, but recognized as not belonging to the bicolor group by its different mandibular gland substances, was notable in having butanoate esters in its Dufour glands. Despite these differences among species, both the great variability of individuals from a single colony and the among between conspecific colonies make species diagnosis from a few individuals difficult, in contrast with postpharyngeal glands, which, as recently reported, give a clearer indication of species.     

Mikrostruktur und Anlaßverhalten aufgedampfter bzw. thermisch gespritzter ZrO2-Schichten auf metallischen Substraten

Microstructure and Tempering Behaviour of Evaporated resp. Thermally Sprayed ZrO₂-Layers on Metallic Substrates Because of their application in gas turbines plasmasprayed thermal barrier coatings of partially stabilized zirconia on metallic substrates are an example for the technical use of ceramic-metal-composites. Problems especially concerning the interface adhesion are still partly not understood. In this paper several systems are examined by electron microscopy, which all consist of ceramic zirconia layers evaporated or thermally sprayed on a metallic substrate. Priority is given to structural analysis. An attempt is made to lighten the interface morphology by the method of cross section preparing, because thereby the possibility of aimed preparation is given.     

First observation of the fourth neutral polarization point in the atmosphere

In the clear sky there are three commonly known loci, the Arago, Babinet, and Brewster neutral points, where the skylight is unpolarized. These peculiar celestial points, bearing the names of their discoverers, have been the subject of many ground-based investigations, because their positions are sensitive indicators of the amount and type of atmospheric turbidity. According to theoretical considerations and computer simulations, there should exist an additional neutral point approximately opposite to the Babinet point, which can be observed only at higher altitudes in the air or space. Until now, this anonymous "fourth" neutral point has not been observed during air- or space-borne polarimetric experiments and has been forgotten, in spite of the fact that the neutral points were a basic tool in atmospheric research for a century. Here, we report on the first observation of this fourth neutral point from a hot air balloon. Using 180 degrees-field-of-view imaging polarimetry, we could observe the fourth neutral point at 450, 550, and 650 nm from different altitudes between 900 and 3500 m during and after sunrise at approximately 22 degrees - 40 degrees below the anti-solar point along the anti-solar meridian, depending on the wavelength and solar elevation. We show that the fourth neutral point exists at the expected location and has characteristics similar to those of the Arago, Babinet, and Brewster points. We discuss why the fourth neutral point has not been observed in previous air- or space-borne polarimetric experiments.     

Optical and Structural Properties of CdTe Grown by Molecular Beam Epitaxy at Low Temperature for Resonant-Cavity-Enhanced HgCdTe Detectors

Investigation into resonant-cavity-enhanced (RCE) HgCdTe detectors has revealed a discrepancy in the refractive index of the CdTe layers grown by molecular beam epitaxy (MBE) for the detectors, compared with the reported value for crystalline CdTe. The refractive index of the CdTe grown for RCE detectors was measured using ellipsometry and matches that of CdTe with an inclusion of approximately 10% voids. X-ray measurements confirm that the sample is crystalline and strained to match the lattice spacing of the underlying Hg_(1−x)Cd_(x)Te, while electron diffraction patterns observed during growth indicate that the CdTe layers exhibit some three-dimensional structure. Secondary ion mass spectroscopy results further indicate that there is enhanced interdiffusion at the interface between Hg_(1−x)Cd_(x)Te and CdTe when the Hg_(1−x)Cd_(x)Te is grown on CdTe, suggesting that the defects are nucleated within the CdTe layers.     

Kriterien zur Auswahl von Aluminium-Legierungen für Wärmetauscherlamellen

Selecting Al Alloys for Light Weight Heat Exchanger Fins Aluminium usage for heat exchangers for the motor car industry has increased significantly in recent years. The intrinsic advantage of aluminium alloys has enabled the replacement of traditional heat exchanger materials such as brass and copper. Alloy development has enabled the aluminium industry to prepare a range of alloys in different conditions and gauges that can meet the requirements of heat exchanger designers. This paper refers to the background for choice of available alloys and to development trends on a fitness for purpose basis.