A note on normal bases of ideals in sextic algebraic number field

Let K/Q be a cyclic tamely ramified extension of degree 6, then any ambiguous ideal of K has a normal basis. Supported by grants GACR 201/07/0191, VEGA 2/4138/04, VEGA 1/0084/08.     

Proximity effect in Fe/Pb/Fe trilayers

We have studied superconducting and magnetic properties of sputtered Fe/Pb/Fe-trilayers. For a fixed Pb thickness and with changing Fe thickness, , a monotonic decrease of the superconducting transition temperature was observed. Magnetization measurements clearly showed that Fe remains ferromagnetic down to the monolayer range. A quantitative comparison of with the theory of pair breaking by the exchange field reveals that the observed -suppression by the ferromagnetic Fe-layer is much weaker than expected. Possible reasons for the reduced -suppression in this system are discussed. Received: 30 June 1997 / Revised: 20 August 1997 / Accepted: 16 December 1997     

Reversible self-propelled droplet movement: a new driving mechanism

Reversible self-propelled movements of droplets of long chain alkanes are presented and analyzed. Slightly above the bulk melting temperature, solid alkane multilayers melt into droplets which move in a self-avoiding, random path. While moving, the droplets consume the solid alkane and leave behind a widening groove. At temperatures slightly below bulk melting this process can be reversed. Now the droplets move backwards leaving behind a narrowing solid trail which is nourished by the shrinking droplet. The speeds of the droplets are analyzed quantitatively and the melting enthalpy is identified as energetic source for their movement.     

Spreading and two-dimensional mobility of long-chain alkanes at solid/gas interfaces

Long-chain n alkanes on solid surfaces can form partially wetting liquid alkane droplets coexisting with solid multilayer terraces. We propose a diffusivelike alkane flow between terrace edge and droplet perimeter through a molecularly thin "precursorlike" film. Depending on the (uniform!) sample temperature, either droplet or terrace edge are not in thermodynamic equilibrium. This leads to a chemical potential gradient, which drives the reversible alkane flow. The gradient can be adjusted and calculated independently from the phenomenological diffusion coefficient.     

Laser desorption/ionization coupled to tandem mass spectrometry for real-time monitoring of paraquat on the surface of environmental particles

Aerosol mass spectrometry with laser desorption/ionization was investigated as a possible tool for real-time monitoring of the presence of the pesticide paraquat on the surface of airborne soil particles. Laser desorption/ionization of paraquat dication produced only singly charged ions. The most abundant species were [M](+.), [M - H](+), and [M - CH3](+). Operation of the ion trap mass spectrometer in the MS(3) mode allowed the reduction of the signal dependence on laser fluence fluctuations and permitted the detection of the analyte with good sensitivity and high selectivity. The estimated limit of detection in terms of surface coverage was 0.016 monolayers, approximately 1 attomole of paraquat on the surface of a single micron-sized soil particle.     

A model technique for analysis of nonlinear structures

Analysis of structural systems which display geometrical nonlinearity may be carried out in some cases with the aid of a digital computer. Convergence of numerical computations is, however, not always assured, and the computer time required is usually a multiple of the time needed for linear analysis. An experimental method to determine stress resultants and displacements, by taking into account geometrical nonlinearity, is suggested. The method consists of loading a model in two stages. First, a fraction of the dead and live loads is applied such that the displacements of the system remain small and its behavior may be considered as linear. Then, the model is loaded with its full dead and live loads under which it displays its real, nonlinear behavior. Strains and displacements are recorded for both cases. By comparing the two readings, that is, by dividing the second readings by the first ones, the nonlinearity of the system is determined. The method is suggested for every project in which nonlinear behavior may be a significant factor.     

A new packing motif for para-sulfonatocalix[4]arene: the solid state structure of the para-sulfonatocalix[4]arene D-arginine complex

The solid-state structure of the complex of para-sulfonatocalix[4]arene with d-arginine, contains a water channel diagonal to a zigzag bilayer of the host, within the bilayer six crystallographically independent molecules of arginine are present, four being included in the calix cavities.     

Conservation and Balance Laws in Linear Elasticity of Grade Three

In the present paper we investigate conservation and balance laws in the framework of linear elastodynamics considering the strain energy density depending on the gradients of the displacement up to the third order, as originally proposed by Mindlin (Int. J. Solids Struct. 1, 417–438, 1965). The conservation and balance laws that correspond to the symmetries of translation, rotation, scaling and addition of solutions are derived using Noether’s theorem. Also, the formulas of the dynamical J,L and M-integrals are presented for the problem under study. Moreover, the balance law of addition of solutions gives rise to explore the dynamical reciprocal theorem as well as the restrictions under which it is valid.