Study of the diffusion of trace elements and radionuclides in soils

Thin layer method of measuring diffusion processes was modified to shorten time and to increase efficiency of experiments. For this purpose small and fine glass capillaries of 20 mm length and inner diameter of several millimeters were used as diffusion cells. The diffusion of trace amounts of¹³⁷Cs, its dependence on soil moisture and interaction with the soil have been studied. Experimental technique. evaluation of records and the basic interpretation of the migration process are described.     

Improvement in the determination of accuracy of enthalpy of ionization from the isothermal deep level transient spectroscopy

In this paper we propose to use a combination of a modified isothermal Deep Level Transient Spectroscopy (IDLTS) method with optical excitation and a filtering method of multi-exponential decays for IDLTS signal represented by a nonexponential transient capacitance. Excellent agreement with published results is achieved using this method for the investigation of a hole trap response (HL4) interfering with other traps in Schottky barriers that were fabricated on an epitaxial GaAs layer grown by VPE on bulk N-GaAs.The authors express sincere thanks to I. Thurzo and F. Dubecký of the Slovak Academy of Sciences who provided samples for these experiments and for useful advice.     

Mössbauer and TEM studies of the perovskite system (1-y)La2/3 $$A$$ 1/3TiO3·yLaFeO3

The microscopic nature of the Mössbauer phase analysis has been found as being particularly valuable in testing assumptions suggested by TEM results regarding the microdomain structure and the population of different lattice sites by iron ions in the perovskite system (1-y)La_{2/3 1/3}TiO₃·yLaFeO₃ with 0.04<y < 0.25 ( is an A-site vacancy). This system was found to contain only Fe₃₊-phases which are stable under normal conditions, but moderate heating in vacuo causes a partial reduction of ferric ions to ferrous ions.     

Acetic Acid Based Sol-Gel PLZT Thin Films: Processing and Characterization

PLZT 4/65/35 thin films were prepared by the acetic acid based sol-gel route. The choice of lanthanum precursor, i.e., acetate or nitrate, influences the functional group content of formamide modified sols and the microstructure of the thin films. The lanthanum nitrate based PLZT thin film deposited on Si/SiO2/TiO2 /Pt/TiO2 substrate has a columnar perovskite grain structure, while the lanthanum acetate based one is characterized by a lead-silicon containing reaction layer beneath the platinum electrode. Although lead is depleted from the PLZT thin film the perovskite structure is retained by the use of the top layer with a large excess of PbO.     

Investigation of the anodic processes on platinum in perchlorate and chlorate solutions by linear sweep voltammetry using the rotating double-ring electrodes

The polarographic behavior of chloramine-T has been investigated over a wide pH range. Chloramine-T gives two waves at low concentration. In acidic solution, the second wave is due to the formation of mercurous chloride, whereas, in alkaline solution, the second wave is due to the formation of the mercuric salt of p-toluenesulfonamide. The diffusion current of the total wave is due to a two-electron reduction, is proportional to the concentration and is stable, particularly in alkaline solution. The polarographic behavior of the anodic wave of p-toluenesulfonamide has also been investigated.     

Determination of tritium in natural waters

A study of the tritium content of precipitation and of river water samples, collected during a seasonal maximum of tritium concentration in 1976 is given. The measurements were made for precipitation in Belgrade from April to December 1976, and for river water from the Sava (in Belgrade), the Tisa at 137 km, and the Danube at 1425 km, 1174 km, 861 km from the confluence. The maximum monthly value of the tritium content of precipitation is 135 TU, and the Danube at 1425 km has a maximum of 196 TU (627 pCi/l). In general, there is no correlation between the amount of precipitation and river water with tritium content.     

Kinetics and precipitation mechanism of sparingly soluble alkaline earth sulfates

Summary Phenotypical and genotypical characteristics of the precipitation phenomena of barium, strontium and calcium sulfates have been determined and compared to each other. The kinetics of the transition from homogeneous dynamic systems into heterogeneous quasi static systems have been investigated by tyndallometric light scattering technique, by electrophoretic determination the charge sign on particles. In the obtained general precipitation diagrams stress the outer precipitate — clear solution boundaries as well as discontinuities in the structure of the precipitate itself.

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Zusammenfassung Es wurden phenotypische und genotypische Eigenschaften der Präzipitationsprozesse von Barium-, Strontium- und Calcium-Sulfat bestimmt.Die Kinetik wurde mittels der Lichtstreuungsmethode und elektrophoretischer Bestimmungen untersucht.Die Ergebnisse wurden in Präzipitationsdiagrammen dargestellt.

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With 3 figures     

Synthesis,characterization and screening of biological activity of Zn(II), Fe(II) and Mn(II) complexes with trithiocyanuric acid

New Zn(II), Fe(II) and Mn(II) complexes with a combination of nitrogen-donor ligands and trithiocyanuric acid (ttcH₃) were prepared and characterized by elemental analysis, IR and UV–Vis spectroscopies. The antitumor activity of the prepared complexes, together with already known Ni(II) species, were assayed in vitro against G-361 (human malignant melanoma), HOS (human osteogenic sarcoma), K-562 (human chronic myelogenous leukaemia) and MCF-7 (human breast adenocarcinoma) tumor cell lines. The IC₅₀ values of the Fe(II) and Mn(II) compounds turned out to be lower than those of cisplatin and oxaliplatin. The antimicrobial activities were evaluated by MIC against bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis). The molecular structure of [Zn(taa)(ttcH)] · H₂O (taa = tris(2-aminoethyl)amine) was determined by X-ray diffraction. The central atom is pentacoordinated by four N atoms of taa and one N atom of the ttcH dianion.     

Influence of a quality system complying with the requirements of ISO/IEC 17025 standard on the management of a gamma-ray spectrometry laboratory

The motives for and the implementation of a quality system complying with the requirements of the ISO/IEC 17025 standard in a gamma-ray spectrometry laboratory are briefly described, as well as its influence on the laboratory's work and output. The use of the quality system as a tool for managing and controlling the state of the laboratory is described. Two examples of control and improvement of the laboratory's performance are given.     

Radiochemical determination of210Po and210Pb in water

A method for²¹⁰Po and²¹⁰Pb determination in water samples is described. The nuclides are concentrated, in presence of added²⁰⁸Po and lead carrier, by evaporation. Then the polonium is plated electroless from the acidic solution on a copper planchet and measured by alpha spectrometry.²¹⁰Pb separation from the other isotopes is based on the solutility of PbSO₄ in citrate.²¹⁰Pb content is determined by measuring the activity of its daughter²¹⁰Bi. The critical steps in the isolation of lead have been examined and discussed.