Analysis of actinides in the primary coolant of a WWER-440 type reactor

A simple and effective method has been developed for the determination of the transuranium isotopes in primary coolant samples of WWER-440 type reactors. Membrane filters containing undissolved particles from about one liter coolant were destroyed by mineral acids, then americium-curium isotopes and neptunium-plutonium isotopes were coprecipitated sequentially with NdF₃ based on their different redox behavior. Alpha-spectra were determined by silicon semiconductor detectors connected to multichannel analyzers. Activity ratios measured in a reactor unit with a failed fuel element were compared with calculated values of the same type of reactor under similar conditions. Parameters of the defective fuel (burnup, original enrichment) could be estimated.     

Dual-mode recognition of oxalate by protonated azacryptate hosts; conformational response of the guest maximizes pi-stacking interactions

Exceptionally large complexation constants for oxalate encapsulated within azacryptand hosts are partly explained by pi-stacking interactions between C=O and aromatic rings.     

Aggregati di cerchi di Minkowski

Sunto Uno teorema diFejes Tóth [2] che si riferisce algi aggregati di cerchi diMinkowski nel piano euclideo sarà esteso alle superficie a curvatura costante. Alla memoria di Guido Castelnuovo, nel primo centenario della nascita.     

Differential freeze-out and pion interferometry at RHIC from covariant transport theory

Puzzling discrepancies between recent pion interferometry data on Au+Au reactions at square root of s=30 and 200 AGeV from RHIC and predictions based on ideal hydrodynamics are analyzed in terms of covariant parton transport theory. The discrepancies in the R(out)/R(side) ratio are significantly reduced when the finite opacity of the gluon plasma is taken into account. However, the magnitude of the radii is not well accounted for.     

Organically modified Pd-silica catalysts applied in Heck coupling

Pd-silica catalysts prepared by depositing Pd onto silica precursors modified by surface methyl or phenyl groups through the reduction of Pd2+ ions with surface Si-H functions exhibit high activity and selectivity in Heck coupling.     

High-throughput prediction of blood-brain partitioning: a thermodynamic approach

A high-throughput in silico screening tool for potentially CNS active compounds was developed on the basis of the correlation of solvation free energies and blood-brain partitioning (log(cbrain/cblood) = log BB) data available from experimental sources. Utilizing a thermodynamic approach, solvation free energies were calculated by the fast and efficient generalized Born/surface area continuum solvation model, which enabled us to evaluate more than 10 compounds/min. Our training set involved a structurally diverse set of 55 compounds and yielded a function of log BB = 0.035Gsolv + 0.2592 (r = 0.85, standard error 0.37). Calculation of solvation free energies for 8700 CNS active compounds (CIPSLINE database) revealed that Gsolv is higher than -50 kJ/mol for the 96% of these compounds which can be used as suitable criteria for the identification of compounds preferable for CNS penetration.     

Capillary zone electrophoresis of orotic acid in urine with on-line isotachophoresis sample pretreatment and diode array detection

Two hydroxide-selective microbore analytical columns (the Dionex AS11 and AS15) were tested and compared for the quantitation of anionic species in 30% hydrogen peroxide. The ions of interest were fluoride, acetate, formate, chloride, bromide, nitrate, sulfate, and phosphate. Statistically sound calibration and spiking studies were carried out, investigating the range of a blank to 60 ppb. Prior to injection onto the separators, peroxides were loaded without pretreatment onto a concentrator column, which was then washed with deionized water to remove the matrix. Although retention times gradually decreased during the spiking studies, reliable quantitation was still achievable on both columns at the target concentration of 30 ppb. However, various resolution problems meant that the AS11 should not be recommended for this application.     

The decoupling problem at RHIC

We investigate whether it is possible to dynamically generate from classical transport theory the observed surprising R_out ≈ R_side in Au+Au at \(\sqrt s = 130A\) GeV at RHIC [1,2]. We obtained covariant solutions to the Boltzmann transport equation via the MPC technique [3], for a wide range of partonic initial conditions and opacities. We demonstrate that there exist transport solutions that yield a freezeout distribution with R _out < R _side for K _⊥ ? 1.5 GeV. These solutions correspond to continuous evaporation-like freezeout, where the emission duration is comparable to the source size. Naively this would mean R _out > R _side. Nevertheless, our sources exhibit R _out < R _side because they are narrower in the‘out’ than in the‘side’ direction and, in addition, a positive x _out-t correlation develops reducing R _out further.     

Freeze-out of the expanding system

The freeze-out (FO) of the expanding systems, created in relativistic heavy-ion collisions, is discussed. We start with kinetic FO model, which realizes complete physical FO in a layer of given thickness, and then combine our gradual FO equations with Bjorken-type system expansion into a unified model. We shall see that the basic FO features, pointed out in the earlier works, are not smeared out by the expansion.