Variation of the Microwave Brightness Temperature of Sea Surfaces Covered with Mineral And Monomolecular Oil Films

Airborne microwave radiometer measurements over mineral and monomolecular oil films and adjacent clean sea surfaces are reported. An artificial crude-oil spill experiment in the New York Bight area showed a brightness temperature increase of the sea surface at 1.43 GHz as expected from a multilayered system with different dielectric constants. However, a monomolecular surface-film experiment with oleyl alcohol conducted in the North Sea during MARSEN in 1979 showed a strong brightness temperature depression at 1.43 GHz and no change in brightness temperature at 2.65 GHz. It is postulated that the monomolecular layer, because of its physical and chemical properties, polarized the underlying water molecules so strongly that the emissivity decreased from 0.31 to 0.016. It is estimated that the effective dielectric constant changed from 90 to 5.2 × 104. Because these phenomena occurred at 1.43 GHz it may be concluded that this frequency is very close to the center of a new anomalous dispersion region resulting from a restructuring of the water layer below the surface film.     

Zur Bestimmung der Wärmeleitfähigkeit von Eisenschwamm

Messung der Wärmeleitfähigkeit von Eisenschwamm nach der Laserimpuls-Methode bei Temperaturen zwischen 20 und 1400°C. Vergleich der Meßwerte mit der Wärmeleitfähigkeit von Reineisen. Theoretische Überlegungen zum Temperaturverlauf der Wärmeleitfähigkeit des Eisenschwamms.     

Information transport and computation in nanometre-scale structures

We discuss two examples of novel information-transport and processing mechanisms in nanometre-scale structures. The local modulation and detection of a quantum state can be used for information transport at the nanometre length-scale, an effect we call a 'quantum mirage'. We demonstrate that, unlike conventional electronic information transport using wires, the quantum mirage can be used to pass multiple channels of information through the same volume of a solid. We discuss a new class of nanometre-scale structures called 'molecule cascades', and show how they may be used to implement a general-purpose binary-logic computer in which all of the circuitry is at the nanometre length-scale.     

Microcontact printing of DNA molecules

The controlled placement of DNA molecules onto solid surfaces is the first step in the fabrication of DNA arrays. The sequential deposition of tiny drops containing the probe DNA fragments using arrays of spotting needles or ink jet nozzles has become a standard. However, a caveat of liquid spotting is the drying of the deposited drop because this creates the typical inhomogeneities, i.e., rims around the spot. Another drawback is that each DNA array is an original and has to be fabricated individually. Microcontact printing is a versatile technique to place proteins onto different target surfaces in uniformly patterned monolayers with high lateral resolution. Here, we show for the first time that DNA can also be printed with equally high resolution in the submicrometer range using an elastomeric stamp with chemically tailored surface. Two regimes for the transfer of the molecules were observed. Finally, microcontact printing of an array of DNA probes onto a solid support and its use in a subsequent hybridization assay was demonstrated.     

Einfluß von Werkstoffzusammensetzung und Ferritkorngröße auf die Konstanten der Ludwik-Gleichung

Beschreibung der Spannung-Dehnung-Kurve ferritischer und ferritisch-perlitischer Stähle mit der Ludwik-Gleichung. Einfluß der Korngröße auf den Vorfaktor der Ludwik-Gleichung. Anstieg des Vorfaktors mit zunehmendem C- und Mn-Gehalt sowie mit steigendem Perlitanteil am Gefüge. Korngrößenunabhängigkeit des Verfestigungsexponenten. Einfluß des C- und Mn-Gehaltes auf den Verfestigungsexponenten.     

A note on upwinding and anisotropic balancing dissipation in finite element approximations to convective diffusion problems

In one dimension, Petrov—Galerkin nonsymmetric weighting for the convective diffusion equation can be interpreted as an added dissipation. The addition of an appropriate amount of dissipation can therefore give the same oscillation-free solutions as the ‘unwinding’, Petrov—Galerkin, finite element methods. The ‘balancing dissipation’ is optimally chosen so that excessive dissipation does not occur. A scheme is presented for extending this approach to two-dimensional problems, and numerical examples show that the new method can be used with improved computational efficiency.     

Quantitative characterisation of chemical inhomogeneities in Al-Ag using high-resolution Z-contrast STEM

The incoherent imaging model is applied to interpret high-resolution Z-contrast micrographs. A simple method for a column-by-column resolved characterisation of Ag-rich precipitates in Al-Ag is developed. No information on the detailed imaging process is required. Evaluating the high-angle scattering intensities of Al and Ag by image analysis, the number of Ag atoms contained in individual atomic columns can be determined accurately and moreover, the thickness of the thin foil can be calculated. Multislice simulations confirm the broad validity of the incoherent imaging model for Z-contrast STEM and are used to check the method presented. Finally, the image analysis is applied to experimental Z-contrast images of Guinier-Preston zones in Al-3 at% Ag. The Ag content of the individual atomic columns can be determined with an accuracy better than +/-10%.