Model spectral function and superconductivity in BaxK1−xBiO3 (x=0.5-0.7)

The Eliashberg spectral density function is constructed for the superconducting compound Ba_xK_1−xBiO₃ with x=0.5, 0.6, 0.7. The functions, besides yielding some prominent structures, show widely spreading spectra that inhibit lattice instability by yielding not too large values of λ(<1.32). The resulting spectral functions show similar shape as other results, where available, and also successfully reproduce the observed critical temperature, isotope exponent, gap ratio and several other parameters.     

Improvements in Depth Selective Electron Mössbauer Spectroscopy

The conditions for achievement of high resolving power of depth selective conversion electron Mössbauer spectroscopy method at a combined installation ‘electron spectrometer–nuclear gamma-resonance spectrometer’ have been obtained. There has been made a considerable step in development of the method at its realization at a magnetic sector electron spectrometer with double focusing, equipped with electron source (a sample under investigation) of large-area and position-sensitive detector. The paper presents a prospective symmetrical version of a magnetic sector electron spectrometer that allows realizing more completely possibilities of the method. It is noted that the proposed method is particularly valuable for investigations of nanosystems, nanostrutures that contain Mössbauer nuclei.     

Zur Trennung des Eisens von Nickel und Kobalt

Ohne Zusammenfassung     

Combined supercritical-fluid chromatography/mass spectrometry in the analysis of diuron in plasma using on-line phase-system switching

On-line sample pretreatment by means of the phase-system switching approach is an interesting technique for the analysis of aqueous samples, e.g., plasma, by means of supercritical-fluid chromatography. In order to analyse plasma samples the following analytical procedure is used. The plasma sample is injected on to a short precolumn, which is washed with water and subsequently dried with nitrogen. Next, the solutes are desorbed with the supercritical mobile phase, analysed with packed-column supercritical-fluid chromatography and detected with either a UV detector or a mass spectrometer, equipped with a moving-belt interface. The herbicide diuron is selected as a test compound to study the feasibility of this approach. Using a selective detector the procedure is sufficiently sensitive to detect diuron in plasma, but not appropriate to detect the diuron metabolites in a post-mortem plasma sample. These have been identified with liquid chromatography/mass spectrometry. The detection limit of diuron in plasma using the procedure described is about 30 ng/mL.     

Collective flow model for the pion transverse momentum spectra from relativistic nuclear collisions at CERN

The transverse momentum spectra for pions observed by WA80 and NA35 collaborations are analysed within a fireball model with collective isentropic expansion and a realistic freeze-out criterion. By varing the initial state of the fireball, an excellent fit to the data is achieved for the whole measured range ofP _T . Slight differences in the data for the spectral slopes from central and pheripheral collisions originate in our model from the difference in the size of the fireball and in the number of participating nucleons in central and peripheral collisions. Using additional information from two-pion correlations, we can extrapolate our model back from the freeze-out point (determined from the spectra) to the initial state; we find that an initial energy density of 1.5–2GGeV/fm³ is sufficient to explain the data from central O+Au collisions at 200A GeV.     

Effect of superfluidity on the structure of the inner crust of neutron stars

A self-consistent, completely quantum calculation of the structure of the inner crust of neutron stars is carried out in the Wigner-Seitz approximation with a realistic phenomenological nuclear energy functional, where pair correlations of neutrons and protons are included in the explicit form. It has been shown that the superfluidity of neutrons and protons affects the structure of the ground state of the crust.     

Robust Speed Control of a Low Damped Electromechanical System Based on CRONE Control: Application to a Four Mass Experimental Test Bench

Robust speed control of a low damped electromechanical system with backlash is studied, controlled load angular speed being not measured. The proposed control strategy combines a Luenberger observer (load angular speed and load torque disturbance estimations) and a robust CRONE controller. The observer provides estimation of the load angular speed and of the disturbance torque applied on the load. Through the computation of only three independent parameters (as many as a PID controller), the CRONE controller permits to ensure the robust speed control of the load in spite of plant parametric variations and speed observation errors. The proposed control strategy is applied to a four mass experimental test bench.     

Reactions of massive nuclei for the synthesis of heavy and superheavy nuclei

We study the effect of the entrance channel and the shell structure of reacting massive nuclei on the fusion mechanism and the formation of evaporation residues of heavy and superheavy nuclei. In the framework of the combined dinuclear system concept and advanced statistical model, we analyze the reactions ³²S+¹⁸²W, ⁴⁸Ti+¹⁶⁶Er and ⁶⁰Ni+¹⁵⁴Sm leading to ²¹⁴Th^*, and the reactions ⁴⁸Ca+²⁴⁸Cm and the ⁴⁸Ca+²⁴⁹Cf leading to the ²⁹⁶116 and ²⁹⁷118 compound nuclei, respectively.