A facile and efficient procedure for the synthesis of new benzimidazole-2-thione derivatives

A series of benzimidazole-2-thione derivatives was synthesized using a reaction between the macrocyclic aminal 16H,13H-5:12,7:14-dimethanedibenzo[d,i]-[1,3,6,8] tetraazecine (DMDBTA, 5) and various nucleophiles in the presence of carbon disulfide. A full chemical characterization using IR, 1H-, 13C-NMR and GC-MS analyses of the new compounds is provided. These compounds were separated from the reaction mixture by column chromatography (CC) in highly pure form in 15%-51.4% yield.     

A new tool for painting diagnostics: Optical coherence tomography

Nondestructive techniques have seen successful growth in the last few years, and, among them, optical ones are widespread and extremely well received in the field of painting diagnostics because of their effectiveness and safety. At present, many techniques for nondestructive investigations of paintings are available; nevertheless, none of them is suitable for a quantitative characterization of varnish. However, varnish removal, either partial or complete, is a fundamental part of the cleaning process, which is an essential step in painting conservation. This critical process has been carried out, up to now, without the possibility of any non-destructive measurement for assessing the actual varnish thickness, but with microscopic observation of a detached microfragment. Optical coherence tomography (OCT) is a noninvasive technique that is well established for biomedical applications. In this work, we present a novel application of OCT to measure the varnish film thickness for painting diagnostics. The text was submitted by the authors in English.     

Inflaton field governed universe from NKK theory of gravity: stochastic approach

We study a non-perturbative single field (inflaton) governed cosmological model from a 5D non-compact Kaluza-Klein (NKK) theory of gravity. The inflaton field fluctuations are estimated for different epochs of the evolution of the universe. We conclude that the inflaton field has been sliding down its (quadratic) potential hill along the whole evolution of the universe and a mass is involved of the order of the Hubble parameter. In the model here developed the only free parameter is the Hubble parameter, which could be reconstructed in the future from Super Nova Acceleration Probe (SNAP) data. Received: 17 August 2005, Revised: 12 September 2005, Published online: 14 October 2005 PACS: 04.20.Jb, 11.10.kk, 98.80.Cq     

Ab Initio Calculation of Hyperfine Interaction Parameters: Recent Evolutions, Recent Examples

For some years already, ab initio calculations based on Density Functional Theory (DFT) belong to the toolbox of the field of hyperfine interaction studies. In this paper, the standard ab initio approach is schematically sketched. New features, methods and possibilities that broke through during the past few years are listed, and their relation to the standard approach is explained. All this is illustrated by some highlights of recent ab initio work done by the Nuclear Condensed Matter Group at the K.U.Leuven.     

Neutral pion production in subthreshold heavy ion collision with16O (38 MeV/u) and20Ne (200 MeV/u) beams

Inclusive production of neutral pions has been studied in¹⁶O +²⁷Al,¹⁹⁷Au reactions at 38 MeV/u and²⁰Ne +²⁷Al reaction at 200 MeV/u. A setup of 10 Pb glass Cherenkov detector telescopes was used to detect the twoγ rays from theπ ⁰ decay.     

Two-photon Fourier spectroscopy with femtosecond light pulses

We demonstrate a Fourier spectrometer that uses intense ultrashort laser pulses. By exciting the 6S(1/2) - 8S(1/2) two-photon transition in atomic cesium vapor, we are able to measure the small hyperfine splitting of the 8S(1/2) excited state. This technique, combining a high spectral resolution with the high peak intensities available to femtosecond laser systems, may offer intriguing opportunities for the study of multiphoton transitions and for spectroscopy in the short-wavelength region.