Formation of Zr I and II lines under non-LTE conditions of stellar atmospheres

The non-local thermodynaic equilibrium (non-LTE) line formation for the two ions of zirconium is considered through a range of spectral types when the Zr abundance varies from the solar value down to [Zr/H] = -3. The model atom was built using 148 energy levels of Zr I, 772 levels of Zr II, and the ground state of Zr III. It was shown that the main non-LTE mechnism for the minority species Zr I is ultraviolet overionization. Non-LTE leads to systematically depleted total absorption in the Zr I lines and positive abundance corrections, reaching to 0.33 dex for the solar metallicity models. The excited levels of Zr II are overpopulated relative to their thermodynamic equilibrium populations in the line formation layers due to radiative pumping from the low-excitation levels. As a result, the line source function exceeds the Planck function leading to weakening the Zr II lines and positive non-LTE abundance corrections. Such corrections grow towards lower metallicity and lower surface gravity and reach to 0.34 dex for Teff = 5500 K, log g = 2.0, [M/H] = -2. As a test and first application of the Zr I-Zr II model atom, Zr abundance was determined for the Sun on the basis of 1D LTE model atmosphere. Lines of Zr I and Zr II give consistent within the error bars non-LTE abundances, while the difference in LTE abundances amounts to 0.28 dex. The solar abundance of zirconium obtained with the MAFAGS solar model atmosphere is log eps(Zr) = 2.63+-0.07.Comment: published in Astron. Letters, 36, 664 (2010); Erratum was submitte

Microbiological Control in Decontamination of Sludge from Wastewater Treatment Plant

Dynamics of the microbiological indicators of fresh sludge from wastewater treatment plants with a concentration of CaO, 10% and 20%, and ash, −30% and 50%, and treated with quicklime, ash, and microbial fertilizer for a 50-day period of composting were studied. The influence of temperature, water content, and oxygen on the development of microbes was established in laboratory conditions. Microbiological analysis included the determination of non-pathogenic (non-spore-forming bacteria, bacilli, actinomycetes, micromycetes, bacteria digesting mineral nitrogen), and pathogenic (Salmonella, Listeria, Escherichia coli, Enterococcus, Clostridium perfringens) microorganisms. Of the beneficial microflora in the sludge before treating, the amount of non-spore-forming bacteria was the highest, followed by bacilli and micromycetes. It was found that actinomycetes were absent in the untreated sludge. Clostridium perfringens occupied a major share in the composition of the pathogenic microflora, followed by Escherichia coli, Enterococcus, and Listeria. The best results for decontamination of the sludge were obtained by adding 20% quicklime and 50% ash. Alkalization of the sludge after treatment led to the destruction of pathogenic microflora but also reduced the number of beneficial microorganisms. The decrease in pH during the study period determined the redevelopment of pathogenic microflora. Combined variants with lime or ash and microbial fertilizer showed better results for the development of non-pathogenic microflora and the destruction of pathogens

Radiative parameters of Nb I excited states

peer reviewe

Radiative lifetimes and transition probabilities in Rh I

peer reviewe

Radiative decay parameters for highly excited levels in Ti II

peer reviewe

Lifetime measurements of even and odd states in neutral terbium (Tb I)

Radiative lifetimes of 7 odd and 11 even parity states of Tb I (Z = 65) have been measured by the time resolved laser induced fluorescence method (TR-LIF). Experimental data for 9 out of the 18 states are obtained for the first time. The radiative lifetimes presented in this study are in good agreement with previous TR-LIF experimental results but systematically shorter than those obtained by the delayed coincidence technique

Application of Laser Induced Breakdown Spectroscopy (LIBS) to the determination of transition probabilities of laser lines in Au II spectrum

Experimental branching fractions for laser lines arising from excited states of 5d97s configuration of Au II have been determined by application of Laser Induced Breakdown Spectroscopy (LIBS). The experimental relative transition probabilities were converted into an absolute scale using theoretical values for the radiative lifetimes of the corresponding states, calculated in this work. Transition probabilities and radiative lifetimes have been determined by a relativistic Hartree - Fock method taking configuration interaction and core-polarization effects into account. A comparison of the present results with the available theoretical values has been made and shows a reasonable agreement although discrepancies are observed between theory and experiment for some transitions

Radiative parameters for some transitions arising from the 3d(9)4d and 3d(8)4s(2) electronic configurations in CuII spectrum

Transition probabilities of 41 transitions originating from the 3d(9)4d and 3d(8)4s(2) electronic configurations of singly ionized copper have been determined using laser-induced breakdown spectroscopy. The Cu II ions have been produced by laser ablation. The experimental relative transition probabilities have been converted into an absolute scale using measured branching fractions and theoretical radiative lifetimes of the corresponding upper states obtained by a relativistic Hartree-Fock method taking core-polarization and configuration interaction effects into account. Comparison of the new results with previously available data is also presented

Radiative lifetimes of Zr III excited levels

We report on radiative lifetimes of 4d5p excited states of Zr III produced in a laser produced plasma. The ions were populated either in the ground state or in metastable states, and the number of ions is strongly dependent on the application of an external magnetic field, which is shown to be very important when using the time-resolved laser-induced fluorescence technique for lifetime measurements in highly charged ions. The experimental lifetime results fall in the region 1–2 ns with statistical uncertainties less than 7%. The experimental values were compared with multi-configuration Hartree-Fock calculations showing an agreement within 12–20%. The experimental values are systematically higher than the theoretical ones