Radioactivity in technological NPP waste

Concentrations of radionuclides in liquid and solid technological waste of the South-Ukrainian Nuclear Power Plant were studied. It is shown that correlated variation in radionuclide content of all samples is observed. Simple relations are derived for evaluating concentrations of radionuclides from the data on the ⁶⁰Co and ¹³⁷Cs activities. Original Russian Text ? M.D. Bondar’kov, A.M. Maksimenko, I.N. Vishnevskii, V.A. Zheltonozhskii, M.V. Zheltonozhskaya, L.V. Sadovnikov, S.V. Il’ichev, V.V. Boyarishchev, 2009, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 2, pp. 279–282.     

Busy period,virtual waiting time and number of customers in G<Superscript><Emphasis Type="Italic">δ</Emphasis></Superscript>|M<Superscript><Emphasis Type="Italic">ϰ</Emphasis></Superscript>|1|B system

In this article, we determine the integral transforms of several two-boundary functionals for a difference of a compound Poisson process and a compound renewal process. Another part of the article is devoted to studying the above-mentioned process reflected at its infimum. We use the results obtained to study a G ^δ |M ^ϰ |1|B system with batch arrivals and finite buffer in the case when δ∼ge(λ). We derive the distributions of the main characteristics of the queuing system, such as the busy period, the time of the first loss of a customer, the number of customers in the system, the virtual waiting time in transient and stationary regimes. The advantage is that these results are given in a closed form, namely, in terms of the resolvent sequences of the process.     

Reactions of N-sulfonyl-1,2,3-thiadiazole-4-carbimidamides with sulfonyl chlorides: regiospecific synthesis and structure of 2-sulfonyl-1,2,3-triazoles

Chemistry of Heterocyclic Compounds - Sulfonylation of 1,2,3-thiadiazolecarboxylic acid amidines in the presence of a base was found to be accompanied by the Cornforth rearrangement of the...     

High-Yield Synthesis of New Ni–Ru Carbido–Carbonyl Clusters

Four new bimetallic Ni–Ru mixed-metal carbido–carbonyl clusters of a general formula [NiRu₅C(CO)₁₄ L₂], where L₂ = dppe (2), dppp (5), (PPh₃)₂ (8) and (PBu₃)₂ (13) were synthesised following the general synthetic strategy using penta- and hexaruthenium carbido carbonyl dianions in the reactions with corresponding dichloro complexes of Ni(II). The molecular and crystal structures of 2, 5, 7, 8, and 13 were determined by single crystal X-ray analysis. The mixed-metal core is octahedral with the P atoms coordinating to the Ru atoms.     

Functionalisation of the template-free and template-structured silica films synthesised on glass substrates by sol–gel technique

Possibility of the post-synthesis functionalisation of the template-free and template-structured silica films of ca. 200 nm thickness on glass slides was evaluated. The films were prepared by dip-coating from TEOS sol–gel precursor in the absence or presence of CTAB template. It has been found out that the template-structured silica films can be functionalised with Ag nanoparticles via [Ag(NH₃)₂]NO₃ ion-exchange or with adsorbed Methylene Blue (MB) cationic dye due to the presence of the well-organised mesopores after template removal. In contrast, only the external geometric surface of the template-free silica films appeared to be accessible for modifier molecules. Possibility of functionalisation of the multi-layered template-structured silica film depends on the sequence of dip-coating and calcination steps upon their preparation. When preparation includes reiteration of dip-coating and calcination steps, only the latest top silica film appears to be accessible to modifier molecules. When preparation includes successive dip-coating cycles accomplished by calcination of the final multi-layered film, all pores appear to be accessible since their formation occurs via simultaneous removal of the template molecules over the whole thickness of the multi-layered template-structured silica film.     

Structure of triblock-copolymers based on poly(ethylene oxide) and poly(acrylamide) with central blocks of varying lengths

Temperature transitions have been studied in the structure of triblock copolymers based on poly(ethylene oxide) and poly(acrylamide) (PAA-b-PEO-b-PAA) with central blocks of varying length and compared with individual polymers and polymer mixtures with analogous composition. It has been established that interaction of the polymer components on account of the formation of systems of intramolecular hydrogen bonds is strengthened by the presence of covalent bonds between the components. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 41, No. 6, pp. 364–370, November–December, 2005.     

Correlated ab initio study of nucleic acid bases and their tautomers in the gas phase,in a microhydrated environment and in aqueous solution. guanine: surprising stabilization of rare tautomers in aqueous solution

Altogether eight keto and enol tautomers of guanine were studied theoretically in the gas phase, in a microhydrated environment (1 and 2 water molecules) and in bulk water. The structures of isolated, as well as mono- and dihydrated tautomers were determined by means of the RI-MP2 method using the extended TZVPP (5s3p2d1f/3s2p1d) basis set. The relative energies of isolated tautomers included the correction to higher correlation energy terms evaluated at the CCSD(T)/aug-cc-pVDZ level. The relative enthalpies at 0 K and relative free energies at 298 K were based on the above-mentioned relative energies and zero-point vibration energies, temperature-dependent enthalpy terms and entropies evaluated at the MP2/6-31G level. The keto form having hydrogen atom at N7 is the global minimum while the canonical form having hydrogen atom at N9 represents the first local minimum at all theoretical levels in vacuo and in the presence of 1 and 2 water molecules. All three unusual rare tautomers having hydrogens at N3 and N7, at N3 and N9, and also at N9 and N7 are systematically considerably less stable and can be hardly detected in the gas phase. The theoretical predictions fully agree with existing theoretical as well as experimental results. The effect of bulk solvent on the relative stability of guanine tautomers was studied by self-consistent reaction field and molecular dynamics free energy calculations using the thermodynamic integration method. Bulk solvent, surprisingly, strongly favored these three rare tautomers over all remaining low-energy tautomers and probably only these forms can exist in water phase. The global minimum (tautomer with hydrogens at N3 and N7) is by 13 kcal/mol more stable than the canonical form (3rd local minimum). Addition of one or two water molecules does not change the relative stability order of isolated guanine tautomers but the respective trend clearly supports the surprising stabilization of three rare forms.     

Compacting of poly(acrylamide)‐poly(vinyl alcohol) grafted copolymers in aqueous solution of phenol and its effect in the copolymers films structure

The interaction of phenol with graft copolymers of poly(acrylamide) to poly(vinyl alcohol) (PVA‐PAA_N) forming intramolecular polycomplexes (Intra PC), and also with PAA, is investigated by the methods of gel chromatography, viscometry, UV and IR spectroscopy. It is shown, that phenol connection with polymers is weak and carried out on the equilibrium mechanism. Under phenol influence the effect of compacting of polymer macromolecules is observed. It is revealed, in particular, by change of the ratio between different H‐bonds structures in polymer films obtained at phenol presence. PVA‐PAA_N connect phenol more effectively, than PAA; the quantity of bound phenol grows with N.     

Polyurethane-Based Extended Release Form of Piroxicam

Summary: The anti-inflammatory effect of piroxicam (Px) immobilized on a polyurethane (PU) matrix was studied in vivo by measuring levels of t-methylimidazole acetic acid (t-MeImAA) in urine of experimental animals. Released into body from the polymeric matrix, Px affected inflammation process, significantly reducing the t-MeImAA levels. The retention of Px within the PU/drug system – largely due to physical modification of the polymer – resulted in durable therapeutic action of the system.