Time-resolved spectroscopy of solid poly(1-vinyl naphthalene)following electron beam pulse radiolysis: pulse radiolytic studies on polymers

Transient emission studies following pulse radiolysis of solid poly(1-vinyl naphthalene) show existence of excited monomers and two excimers. Quenching experiments indicate that excimers are not formed directly by recombination of ions but probably by trapping of migrating monomeric excitation in performed traps whose density is approximately one in 10³.     

Discrete and selective absorption in crystalline molecular nanofilms

Recent research in nano-optical engineering and in nanomedicine as well, seeks for methods of construction of various types of nano-markers, nano-carriers, and ways to deliver drugs to the exactly determined regions of body. In this process it is important to find methods of recognition of certain types of molecules. It is obvious that optical recognition would be the easiest and the most effective way to do it. Our research presents a model of a molecular ultrathin crystalline film and generated exciton system inside it and corresponding methodology of analysis of their optical characteristics. Properties of these spatially very restricted structures are very sensitive to their surrounding surfaces. Using the two-time Green’s functions adapted for crystalline structures with symmetry breaking, and graphical-numerical software, we have calculated the energy spectra and possible exciton states. We have shown that the appearance and the presence of localized states on the surfaces and in the boundary layers of the film depend on the thickness of the film and the film surroundings, presented through the perturbation of parameters on surfaces. Optical properties in these structures demonstrate discrete and very selective resonant absorption spectra, depending on the perturbation on their surfaces.     

An evaluation of microextraction/capillary column gas chromatography for monitoring industrial outfalls

Microextraction and capillary-column gas chromatography techniques are applied to plant discharge streams for repetitive wastewater discharge permit analyses. This combination allows the analyst to reduce sample preparation since microextraction replaces both purge-and-trap for volatiles and microextraction for semi-volatiles. An additional advantage is the elimination of a concentration step, which is often a major contributor to low method recoveries. The overall procedure is shown to be more precise than purge-and-trap but slightly less precise than conventional extraction. The results of each method are shown to be equivalent.     

Regional cooperation in proficiency testing: strategy planning and practical experiences in Western Balkan countries

The article describes the project of regional cooperation in proficiency testing within CARDS 2006 (assistance programme to the Western Balkans), which was coordinated by European Committee for Standardization, European Commission and European Free Trade Association and conducted by the University of Ljubljana, Faculty of Electrical Engineering, Laboratory of Metrology and Quality. The later is the holder of the national standard for thermodynamic temperature as well as an accredited proficiency testing provider and also accredited as a calibration, testing and inspection laboratory. It is also responsible for graduate study programme Quality Engineering. Proficiency testing was considered as a core activity of the entire project, but additionally as a very appropriate platform for knowledge transfer of EU technical legislation in selected sectors, metrology, testing and quality assurance in general. The project had a high added value for participating laboratories in countries of Western Balkans, because it required an active role of all participating laboratories, assured participation of staff from national metrology institutions, all national accreditation bodies, and was supported by national quality infrastructures, such as standardization, governmental institutions etc. in the entire Western Balkans region. The activities stimulated progress in the area of conformity assessment, added knowledge to the implementation of technical directives and development of the technical part of national legislation and therefore facilitated the process toward the accession to the European Union. The main objective was therefore to organize proficiency testing in those sectors (construction, consumer protection and environment) that were vital in the pre-accession process of countries seeking full implementation of EU technical legislation.     

Superspin-glass like behavior of nanoparticle La<Subscript>0.7</Subscript>Ca<Subscript>0.3</Subscript>MnO<Subscript>3</Subscript> obtained by mechanochemical milling

Single-phase perovskite compound La_0.7Ca_0.3MnO₃ was synthesised by a high-energy ball milling in a single step processing. Structure and morphology characterizations revealed nanoparticle nature of this mixed valent manganite with the average particle diameter of 9 nm. Comprehensive set of magnetic measurements showed that the system can be described as an ensemble of interacting magnetic nanoparticles where each particle possesses high magnetic moment, i.e., superspin. Furthermore, magnetic behavior showed contributions from both superspin-glass (SSG) and superparamagnetic (SP) states, and the prevailing properties depended on the experimental conditions. It was established that SSG state dominated in low magnetic fields up to 500 Oe while in higher applied fields suppression of collective behavior occurred and individual characteristics of nanoparticles prevailed. It was also concluded that the applied method of synthesis produced system with high magnetic anisotropy as well as with the large nanoparticle shell whose thickness amounts 30% of a particle diameter.