The E3Σ1+ (63S1)←A3Π0+(53P1) transition in CdAr revisited: The spectrum and new analysis of the E3Σ1+ Rydberg state interatomic potential.

Revisited study of the E3Σ1+ (63S1)←A3Π0+(53P1) transition in CdAr using both theoretical and experimental approach is presented. Systematic detection of the E3Σ1+in,υ'←A3Π0+,υ″=6 transition frequencies with higher accuracy and spectrally narrower laser extended and improved analysis and simulation of the LIF excitation spectrum. More consistent characterization of the E3Σ1+in-Rydberg state inner well using inversed perturbation approach methodology was achieved. Free←bound transitions in the E3Σ1+in←A3Π0+,υ″=6 excitation were taken into account in the analysis and simulation of the recorded spectrum. The updated spectroscopic characterization of the A3Π0+ state was also revisited.

Broadband anti-Stokes white emission of Sr2CeO4 nanocrystals induced by laser irradiation.

The laser induced white emission (LIWE) from Sr2CeO4 nanocrystals upon irradiation with a focused IR laser beam was investigated. It was observed to be a threshold phenomenon with its intensity increasing exponentially with the excitation power density. This process was investigated under double laser beam simultaneous excitation in the UV range leading to Stokes emission in the visible range and in the IR range leading to anti-Stokes LIWE. With increasing LIWE intensity, the Stokes emission intensity strongly decreased. The LIWE is accompanied by efficient photocurrent generation depending on laser excitation density followed by multiphoton absorption and ionization processes. Photoimpedance measurements showed a sharp increase of the dielectric constant by several orders of magnitude in the Sr2CeO4 nanocrystals during the LIWE process demonstrating a metallic-like behaviour. The mechanisms of LIWE include multiphoton absorption and ionization that lead to the creation of a coupled pair of Ce3+ and Ce4+ ions that allow for the intervalence charge transfer (IVCT) emission transitions in the white light range. A strong decrease of absorption band intensity of Sr2CeO4 with increasing LIWE intensity confirms the creation of (Ce3+, Ce4+) pairs.

DNA damage in grasshopper Chorthippus brunneus (Orthoptera) hatchlings following paraquat exposure.

Comet assay was applied to study genotoxic damage induced by paraquat (PQ) in brain cells of Chorthippus brunneus (Insecta: Orthoptera) hatchlings. Percentage of the comet fluorescence in the tail (TDNA), length of the comet tail (TL) and Olive tail moment (OTM) were used for quantitative assessment of the DNA damage. Multiple regression analysis supplemented standard statistical elaboration of the results. Increasing PQ concentrations applied either directly to the brain cells suspension (10, 50, and 250 µM PQ final concentration--in vitro protocol) or indirectly (50, 250, and 1250 µM PQ final concentration--in vivo protocol) provoked significant increase of oxidative damage to DNA (higher median TDNA and OTM values). The damage increased with time of exposure (0, 5, 15, and 30 min) following in vitro application, but decreased in longer interval (3 vs 24 h) after in vivo administration of paraquat. On contrary, median TL values did not correlate with paraquat concentration irrespectively of the exposure protocol. Possible reason of this discrepancy in light of paraquat toxicity is discussed.

Role of the antenna in tissue selective probes built of lanthanide-organic chelates.

The role of the antenna in the process of the host sensitized luminescence of the DOTA cage coordinated with the Eu ion is investigated. The analysis of the optimal geometries of DOTA modified by several antennas is based on the results of density functional theory (DFT) calculations. The physical environment of the luminescence center (the lanthanide ion) is illustrated by charge density maps and described by the values of the crystal field parameters directly evaluated. The conclusions derived from this theoretical analysis support earlier observations that antennas attached to the cage play the sole role of harvesting and transferring the energy to the lanthanide ion, whereas the cage perturbs the symmetry of the environment of the lanthanide ion, giving rise to the sensitized luminescence. The implications of the separation of the two parts of the organic chelate, cage and antenna, are discussed within the theoretical models of the energy transfer and of forced f <--> f electric dipole transitions.

Cadmium-selenium antagonism and detoxifying enzymes in insects.

Activities of non-specific carboxylesterases (CarE) have been studied in adult males of hissing cockroach Gromphadorhina portentosa subjected to prolonged intoxication (7 weeks) with Cd and/or Se to investigate whether sublethal dose of cadmium (0.4 micromol. g(-1) dry weight feed) would influence the detoxifying capabilities of the omnivorous insect, and whether selenium (0.01 micromol. g(-1) dry weight feed) given concomitantly would act as Cd antagonist. Activities of CarE have been measured in crude homogenate, postmitochondrial supernatant and the pellet obtained from midgut, Malpighian tubules and fat body, using alpha-naphthyl acetate (alphaNA) and rho-nitrophenyl acetate (rhoNPA) as substrates. The highest rate of alphaNA hydrolysis occurred in midgut, whereas that of rhoNPA in both the gut and Malpighian tubules. CarE activities in the Cd-group have been the highest in all tissues examined and for both substrates. A simultaneous administration of Cd and Se decreased the effects of Cd alone, probably as a result of partial elimination of the biologically active Cd pool. Selenium alone caused only minor effects when compared with cadmium. These results suggest, that disturbances of CarE activities depend on the Cd concentration in feed, and hence in tissues, as well as on possible interactions of the elements.