[en] The introduction and employment of irradiation technologies in the production attribute to research on the interaction between ionizing radiation and matter and the construction of irradiation installations. After its foundation our institute began at once to set up a gamma irradiation installation imported from the Soviet Union as the basis for radiation chemical investigations in the field of basic and applied research. Since then an efficient potential of 3 closed and 3 open irradiation facilities has been developed and installed at our institute. With this experimental basis the specific efficiency of the ionizing radiation for the construction of radiation technologies in industry, agriculture and environmental protection has been studied. (orig.)

[en] Subjects: Applications and characterisation of sulphate-reducing bacteria in acid lakes in abandanod uranium and lignite mines; biological analysis of the lakes and their sediments; analytical methods and biogeochemical analysis of mining lakes, technical deacidification experiments, balances and models of mass flow in lakes and sediments of mining landscapes

[en] Owing to the unusual matrix of pyrite-acidified mining lakes, the analysis of chemical parameters may be difficult. A number of methodological improvements have been developed so far, and a comprehensive validation of methods is envisaged. The adaptation of the available methods to small-volume samples of sediment pore waters and the adaptation of sensitivity to the expected concentration ranges is an important element of the methods applied in analyses of biogeochemical processes in mining lakes

[en] Radiation induced grafting of chlorinated PVC was carried out in an aqueous dispersion. Graft products of solution chlorinated PVC as well as fluid bed chlorinated PVC were impregnated with pentane at elevated temperature (373-388K) and pressure (0.8-1.2 MPa). Treatment of the impregnated particles with water vapour yields not inflammable plastic foams, but there are remarkable differences between graft products of solution chlorinated PVC (foam density=0.05 g/ml) and fluid bed chlorinated PVC (foam density=0.8 g/ml). It was demonstrated, that it is possible to obtain plastic foams analogous to Styropor on the basis of grafted chlorine polymers. (author) 2 figs.; 1 tab

[en] For application in genetic engineering the solid phase synthesis of oligonucleotides, using polymeric or silica based supports has attained increased importance. Graft polymers, obtained by gas phase grafting of PTFE-powder with styrene have some advantages compared with other supports. The preparation of these graft polymers and the application for the oligonucleotide synthesis are described. (author)

[en] High-burnup (>50 MWd/kgU) spent fuel samples of various sizes were exposed to NaCl solutions under static, anaerobic and reducing conditions. The accumulated corrosion time was about 200 days. Gas phase and leach solutions were analyzed. By dissolving mm sized fragments in large volumes of solution, saturation effects were avoided and upper limits for intrinsic dissolution rates of about 5-20 mg/(m²d) were measured. Surface area normalized reaction rates were significantly lower when using fine grained fuel powder (estimated sample surface area to solution volume ratio S/V ca. 3000 m^-1), indicating saturation effects. The maximum concentrations of Pu and Am in the tests are close to reported solubility limited concentrations in pure 5m NaCl solutions in the absence of radiolysis effects. The presence of iron effectively reduces the solution concentration of all measured radionuclides (except Cs)

[en] The high solubility in the usual solvents makes the chlorinated PVC most suitable for lacquers, adhesives and fibres. For this reason, the radiation-induced solution chlorination of PVC in methylene chloride was studied. The results of many experiments show that during the reaction between chlorine and PVC the solvent (methylene chloride) is chlorinated only in a small percentage to chloroform (9.5%) and finally to tetrachloromethane (0.1%). It was found that the radiation-induced chlorinated PVC has the same structure as the thermally chlorinated polymer, while the thermal stability and the rate of degradation of the radiation products show the better data for application purposes. (author)

[en] The current stage of the use of radiation technique for chemical syntheses on a technical scale is reviewed. In the first part radiation-induced syntheses of low-molecular compounds are described such as syntheses by sulphurization, halogenation, oxydation and other reactions. In the second part radiopolymerization and radiation-induced modifications of high polymers are discussed in detail. The third part deals with synthesizing by means of radiolytic decomposition of polymers. In most cases notes about radiation sources (⁶⁰Co, ¹³⁷Cs, electron accelerators), G-values, reaction yields, radiation doses, costs, and trends of application are made. 283 references are included

[en] The structure of Tl₂SeO₄ at 293, 100 and 30 K has been determined. Space group at 293 and 100 K is Pmcn, Z=4, lattice parameters at 293 K are a=6.0838(12)(100 K: 6.0336(19)), b=10.965(3) (100 K: 10.903(5)) and c=7.9385(15) A(100 K: 7.921(2)). At 30 K space group is P2₁2₁2₁, Z=4, with lattice parameters a=6.2333(17), b=10.533(3) and c=7.828(2). Measurement was carried out with a Stoe IPDS (293 K) and a Nonius CCD using an Oxford He-cryostat for cooling (100 and 30 K). Final agreement factors at 293 K after refinement with the program SHELXL97 are R(F)=0.061 (100 K: 0.097), wR(F**2)=0.051 (100 K: 0.156) for 566(100 K: 678) unique reflections and R(F)=0.039, wR(F**2)=0.097 for 1162 unique reflections at 30 K. The high-temperature phase is isotypical to the β-K₂SO₄ structure, characterized by isolated selenate tetrahedra and two different cation sites with coordination number 9 and 11. In the low-temperature phase, the tetrahedra are rotated and the coordination numbers of the Tl⁺ ions are reduced to 8 and 10, respectively. Structural changes are similar to the ones observed in high- and low-temperature phases of Tl₂MoO₄. A comparison to other Tl₂TX₄ compounds shows that the structural instabilities are closely connected to shortest Tl-O distances

[en] Short communications