[en] Short communication

[en] The main objective of this work was the development of new photocrosslinking and labeling reagents which show favourable photochemical properties and can be synthesized in an extremely high specific radioactivity. A key compound in the synthesis of these reagents was 2-tributyltin-4-(3-trifluormethyl-3H-diazirin-3-yl)-benzyl alcohol. Esters of this alcohol can be easily radioiodinated at a specific radioactivity of >2000 Ci/mmol under mild conditions. By experiments with a model compound it was shown that 2-iodo-4-(3-trifluormethyl-3H-diazirin-3-yl)-benzyl esters, upon photolysis, generate highly reactive (singlet) carbenes capable of inserting into CH-bonds. Equally important, there is no indication of loss of iodine under the photolysis conditions applied. Therefore two key requirements for photolabeling reagents are fulfilled. Several photoactivatable radioiodinated phospholipids have been synthesized. Their properties have been evaluated by labeling of the the membranes of intact erythrocytes and influenza viruses. Currently these lipids are used to study the interaction of various proteins (shown are experiments with MARCKS) with membranes. Furthermore a new class of actual label transfer crosslinkers (two thiol specific and one amino specific) have been developed. The range of potentialities of these reagents is currently being investigated. Finally a photoactivatable radioiodinated ceramide analogue suitable as a photoaffinity crosslinker has been developed with the goal of identifying the putative receptor of this second messenger-like lipid. Preliminary studies towards this goal are described. We are convinced that the reagents and methods presented in this work are valuable tools, and that they will find widespread use in future cell-biological and biochemical research. (author) figs., tabs., refs

[en] In the present paper gamma spectroscopic investigations of ³⁹K and ⁴¹Ca are reported. To this end a novel device for gamma radiation linear polarization measurement, a four-crystal Compton polarimeter, was used. The data were analysed in a model independent way. The results concerning gamma decay and reaction mechanism was interpreted on the base of simple models. For further information see hints under relevant topics. (FKS)

[en] In this thesis the study of the single ionization of helium by protons with incident energies from 200 keV/u to 13.3 keV/u is described. The recoil, electron, and projectile momenta were completely determined for the whole final-state momentum space. (HSI)

[en] The invention has been aimed at developing a single beam ion source of simple design and small dimensions with increased current density in the centre of the ion beam and reduced operating voltage of the gas discharge. The source can be used in transmission electron microscopy

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[en] We discuss the possibility of performing experiments allowing one to test quantum mechanics versus any local realistic model within the context of the physics at the Φ-factory. After having sketched the main features of the physical process under consideration and having focused the locality requirements for it, we derive Bell's inequality for the two-meson system. Comparison with quantum predictions shows that the inequality is not violated for any choice of the parameters characterizing the measurement process. Contrary to the case of spin variables, there is then no way to exclude, by experiments at the Φ-factory, the possibility of a local realistic description of the process. A recent suggestion about a test of quantum predictions versus the assumption of a spontaneous factorization mechanism, as well as the claimed validity of an inequality which is different from Bell's one, are also discussed. The general conclusion is that the Φ-factory facility does not seem to open new ways of testing quantum mechanics versus alternative general schemes of the type which are usually regarded as worth considering the debate about locality and quantum mechanics. The concluding Section is devoted to making clear our position with respect to the problems discussed in this paper. It is pointed out that, in our opinion, the existing experimental evidence makes already clear that one has to accept the ''mysterious'' features of microscopic systems. The really crucial problem is that of investigating whether one can restore a coherent worldview which generally conforms with our experience at the macroscopic level, by keeping all highly successful predictions of quantum theory at the microscopic one. (author). 22 refs

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[en] The United States and Russia are conducting joint technology exchanges on the vitrification of high-level wastes at the Chelyabinsk-65 site in Russia and the Savannah River site in the United States. These activities are part of a larger program of exchanges provided for by a Memorandum of Cooperation (MOC) between the US and the USSR in the fields of Environmental Restoration and Waste Management that was signed in the fall of 1990. An agreement to exchange information in the vitrification area was concluded during a visit by a DOE delegation to Chelyabinsk-65 in the fall of 1991. Samples of simulated high-level waste glass and the leach test procedures used by each country were to be exchanged. The results of studies based on leaching the simulated high-level waste glasses, and potential future work in the area of vitrification, to include advanced concepts, will be discussed