In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.



Volume 52 No. 2 June 2003


Photovoltaic structures formed by thermal annealing of electrodeposited CuInSe2 in H2S; 51–58

Julia Kois, Sergei Bereznev, Enn Mellikov, and Andres Öpik

Abstract. Thin polycrystalline CuInSe2 films were electrodeposited onto ITO/In(O,S) and ITO covered glasses from aqueous solutions with various ratios of elements. The obtained structures were annealed at 450 °C in H2S. Current-voltage and impedance measurements were carried out for the produced heterostructures. The electronic quality of CuInSe2 was found to have improved after thermal and chemical treatment.

Key words: photovoltaic structure, electrodeposition, thermal treatment, chemical treatment.

Observations of ice impurities in some Finnish lakes; 59–75

Matti Leppäranta, Matti Tikkanen, and Juhani Virkanen

Abstract. Ice, snow, and water samples from four lakes and three years were analysed for the impurities (from meltwater). The ice thickness was 30–60 cm. The average concentration of dissolved matter was 11–17 mg/L in ice and 15–23 mg/L in snow. These values were 10–40% of the concentration of dissolved matter in lake water. The sediment content was 2–12 mg/L in all media. The mean metal levels in the ice were 100 mg/L for Al and Fe; 30 mg/L for Zn; 1–10 mg/L for Cu, Mn, and Ni; and below 0.1 mg/L for Cd. These levels were 0.5–2.0 times as high as those in the water. Snowfall is a significant source for many metals. Nutrient levels in the ice were: total-P 2 mg/L; total-N 200 mg/L; SO4, Na, and Cl 1 mg/L; Ca 2 mg/L; and Mg and K 0.5 mg/L. The levels in the ice were by one order of magnitude lower than in the water. Two river ice sites were sampled for reference. These showed by an order of magnitude higher sediment content than the lake ice.

Key words: lake ice, Finland, impurities, sediments, chemical elements.

Assessment of occupational exposure to asbestos in energy and transport enterprises; 76–82

Maie Kangur and Vello Jaakmees

Abstract. Occupational exposure to asbestos in energy and transport enterprises was studied. For the assessment of occupational exposure to asbestos inspections of buildings, asbestos identifica­tion in material samples, and workplace measurements were included. The occurrence of asbestos in buildings from various time periods was studied using relevant acknowledged methods. The methods of polarized light and phase-contrast optical microscopy were used in the qualitative analysis of material samples and in the counting of asbestos fibres in air samples.

Key words: asbestos, identification, occupational exposure.

A study on three-phase ozonation; 83–91

Rein Munter and Yelena Veressinina

Abstract. The paper deals with ozone solubility and reactions in octane and octane–water mixtures. It is shown that ozone solubility in pure octane is about twice as high as in water at the same temperature. In two-phase mixtures, 50% of octane and 50% of water, the solubility coefficients of ozone in both phases are close to each other. It was established that during the ozonation of pure octane and octane–water mixtures organic peroxides were formed, which diffused totally from the organic to the water phase. The ozonation of salicylic, benzoic, and stearic acids was studied in octane–water mixtures.

Key words: ozone, solubility, octane, octane–water mixtures, organic peroxides, salicylic acid, benzoic acid, stearic acid, oxidation.

Mischmetall, zinc–copper couple, and Dewarda alloy in the pinacol coupling of aldimines; 92–96

Eerold Vellemäe, Olga Tšubrik, Olavi Loog, Sirje Mäeorg, and Uno Mäeorg

Abstract. New cheap reagents for the pinacol type coupling reaction of aldimines such as mischmetall, Zn–Cu couple, and Dewarda alloy are introduced. A relatively simple procedure for this reaction is described. Zn–Cu couple should be preferred because of economical considerations.

Key words: mischmetall, Zn–Cu couple, Dewarda alloy, imine, pinacol coupling.