Trace levels of metallic corrosion in water determined by emission spectrography

Emission spectrographic method determines trace amounts of inorganic impurities in potable water. The capability of this innovation should arouse considerable interest among plant biologists, chemists working in organic synthesis, and pathologists

Grain growth inhibitor for porous tungsten materials

Boron, either uncombined or combined with nitrogen or carbon added to tungsten powder prior to processing, effectively inhibits grain growth. The tungsten material is stable up to 1800 degrees C

Thermofield Dynamics of the Heterotic String - Physical Aspects of the Thermal Duality -

The thermofield dynamics of the D = 10 heterotic thermal string theory is described in proper reference to the thermal duality symmetry as well as the thermal stability of modular invariance in association with the global phase structure of the D = 10 heterotic thermal string ensemble.Comment: 8 pages, LaTeX, Minor correction

How to capture active particles

For many applications, it is important to catch collections of autonomously navigating microbes and man-made microswimmers in a controlled way. Here we propose an efficient trap to collectively capture self-propelled colloidal rods. By means of computer simulation in two dimensions, we show that a static chevron-shaped wall represents an optimal boundary for a trapping device. Its catching efficiency can be tuned by varying the opening angle of the trap. For increasing angles, there is a sequence of three emergent states corresponding to partial, complete, and no trapping. A trapping `phase diagram' maps out the trap conditions under which the capture of self-propelled particles at a given density is rendered optimal.Comment: 5 pages, 4 figure

Method of producing refractory bodies having controlled porosity Patent

Production of refractory bodies with controlled porosity by pressing and heating mixtures of refractory and inert metal powder

The origin of the Goths

Witold Ma´nczak has argued that Gothic is closer to Upper German than to Middle German, closer to High German than to Low German, closer to German than to Scandinavian, closer to Danish than to Swedish, and that the original homeland of the Goths must therefore be located in the southernmost part of the Germanic territories, not in Scandinavia (1982, 1984, 1987a, 1987b, 1992). I think that his argument is correct and that it is time to abandon Iordanes’ classic view that the Goths came from Scandinavia. We must therefore reconsider the grounds for adopting the latter position and the reasons why it always has remained popular

The infinite mass limit of the two-particle Green's function in QED

The behavior of the two-particle Green's function in QED is analyzed in the limit when one of the particles becomes infinitely massive. It is found that the dependences of the Green's function on the relative times of the ingoing and outgoing particles factorize and that the bound state spectrum is the same as that of the Dirac equation with the static potential created by the heavy particle. The Bethe-Salpeter wave function is also determined in terms of the Dirac wave function. The present result excludes the existence, in the above limit, of abnormal solutions due to relative time excitations as predicted by the Bethe-Salpeter equation in the ladder approximation.Comment: 13 pages, Tex, no figure

Correlation Energy Estimators based on M{\o}ller-Plesset Perturbation Theory

Some methods for the convergence acceleration of the M{\o}ller-Plesset perturbation series for the correlation energy are discussed. The order-by-order summation is less effective than the Feenberg series. The latter is obtained by renormalizing the unperturbed Hamilton operator by a constant factor that is optimized for the third order energy. In the fifth order case, the Feenberg series can be improved by order-dependent optimization of the parameter. Alternatively, one may use Pad{\'e} approximants or a further method based on effective characteristic polynomials to accelerate the convergence of the perturbation series. Numerical evidence is presented that, besides the Feenberg-type approaches, suitable Pad{\'e} approximants, and also the effective second order characteristic polynomial, are excellent tools for correlation energy estimation.Comment: 21 pages, 87 references, LaTeX2e, elsart.cls, uuencoded compressed tar file created by csh script uufiles. J. Mol. Struct. (THEOCHEM), in press. Postscript and dvi also available via http://www.chemie.uni-regensburg.de/preprint.html and ftp://rchs1.uni-regensburg.de/pub/preprint/TC-QM-96-