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In vitro micronucleus test assessment of polycyclic aromatic hydrocarbons

100%

Żelazna K. , Rudnicka K. , Tejs S.

tom Vol. 7, No. 2

70-80

Polycyclic aromatic hydrocarbons (PAH) can be dangerous due to their genotoxic properties and the formation of DNA adducts in the target organs. The increasing number of environmental pollutants containing polycyclic aromatic compounds requires the use of inexpensive and relatively quick assays enabling evaluation of potential genotoxicity of chemicals. Therefore, the in vitro micronucleus assay (MN) has been developed as a rapid screening test based on measuring and counting the micronuclei in various cells subjected to the examined compound. Combined with the cytokinesis-block micronucleus (CBMN) technique and the fluorescence in situ hybridization (FISH) assay, it also enables classification of compound mutagenic activity into aneugenic or clastogenic categories, the identification of the mechanism of MNi formation and the estimation of malsegregations of chromosomes amongst the two nuclei in binucleated cells. The combination of these different approaches is very useful in performing risk assessments of PAH with threshold types of dose responses.

Technology and properties of low-pressure metalorganic vapour phase epitaxy grown InGaAs/AlInAs superlattice for quantum cascade laser applications

63%

Badura M. , Bielak K. , Ściana B. , Radziewicz D. , Pucicki D. , Dawidowski W. , Żelazna K. , Kudrawiec R. , Tłaczała M.

tom Vol. 46, nr 2

241--248

Quantum cascade laser is one of the most sophisticated semiconductor devices. The active region of the quantum cascade laser consists of hundreds thin layers, thus the deposition precision is the most crucial. The main technique for the fabrication of quantum cascade laser structure is molecular beam epitaxy, however, the prevalence of metalorganic vapour phase epitaxy techniques in the fabrication of semiconductor structures causes a perpetual work on the improvement production of the entire quantum cascade laser structure by the metalorganic vapour phase epitaxy. The paper presents technological aspects connected with the metalorganic vapour phase epitaxy growth of InGaAs/AlInAs low-dimensional structures for quantum cascade laser active region emitting ~9.6 μm radiation. Epitaxial growth of superlattice made of InGaAs/AlInAs lattice matched to InP was conducted at the AIXTRON 3x2″ FT system. Optical and structural properties of such heterostructures were characterised by means of high resolution X-ray diffraction, photoluminescence, contactless electroreflectance and scanning electron microscope techniques. Epitaxial growth and possible solutions of structure improvements are discussed.