An application of nonnegative matrices to the synchronization of chaotic oscillators

The following problem arose in a correspondence between the authors, concerning the exact location of the set of eigenvalues of special real matrices, arising from a problem of synchronization of chaotic oscillators.     

Reductive transformations of unsaturated azabicyclic nitrolactams

Using different reducing methods unsaturated indolizidine and quinolizidine lactams substituted with a nitro group were transformed into various alkaloid-like derivatives. Hydrogen transfer and palladium catalyzed hydrogenation gave compounds of ketolactam or lactam type meanwhile the nitro group was eliminated. On the other hand, in presence of Raney-nickel catalyst the nitro compounds were reduced to diastereomeric amino derivatives whose stereochemistry was elucidated by NMR spectroscopy. Using sodium bis-dimethoxy-ethoxy-aluminum-hydride (Red-Al) as reducing agent an unexpected tricyclic azetidine was isolated and characterized.     

Synthesis and Stereochemistry of Novel Dibrominated 1,5-Dioxaspiro[5.5]undecane Derivatives

 The synthesis and stereochemistry of new dibrominated spiro-1,3-dioxane derivatives are reported. Investigations by means of NMR methods and single crystal X-ray diffraction for two compounds revealed the high regio- and diastereoselectivity of the bromination reaction of some new spiro-1,3-dioxanes and the asymmetric induction of the chiral carbon atom located in the spiro skeleton.     

Existence and multiplicity results for hemivariational inequalities with two parameters

A multiplicity result of Ricceri, based on a minimax inequality, is applied to locally Lipschitz functionals and the existence of one or two non-trivial solutions for a class of two-parameter hemivariational inequalities is proved. An application is given to elliptic problems with discontinuous nonlinearities on unbounded domains.     

Thermal and optical studies on hexa-2,4-diyne-1,6-diyl-bis(4-n-hexoxybenzoate)

As part of a programme investigating mesogenic diacetylenes a symmetrically disubstituted diacetylene has been synthesized and polymerized. Thermal, thermo-optical and IR studies have been carried out to investigate the different crystalline forms of the diacetylene.     

Thionation of a cyanoxime derivative to form the sulphur-containing derivative,a novel ligand for complexation with transitional metal ions

Structural Chemistry - 2-Cyano-2-(hydroxyimino)dithioacetic acid was prepared starting from cyanoacetic acid methylester via 2-cyano-2-(hydroxyimino)acetic acid methylester. Before thionation, the...     

A certified reference material for radionuclides in the water sample from Irish Sea (IAEA-443)

A new certified reference material (CRM) for radionuclides in sea water from the Irish sea (IAEA-443) is described and the results of the certification process are presented. Ten radionuclides (³H, ⁴⁰K, ⁹⁰Sr, ¹³⁷Cs, ²³⁴U, ²³⁵U, ²³⁸U, ²³⁸Pu, ^239+240Pu and ²⁴¹Am) have been certified, and information values on massic activities with 95% confidence intervals are given for four radionuclides (²³⁰Th, ²³²Th, ²³⁹Pu and ²⁴⁰Pu). Results for less frequently reported radionuclides (⁹⁹Tc, ²²⁸Th, ²³⁷Np and ²⁴¹Pu) are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in water samples, for the development and validation of analytical methods and for training purposes. The material is available in 5 L units from IAEA (http://nucleus.iaea.org/rpst/index.htm).     

Accumulation of uranium, transuranium and fission products on stainless steel surfaces II. Sorption studies in a laboratory model system

Within the frame of a joint project, the accumulation of the uranium and transuranium (TRU) species on some structural materials used at Soviet made VVER-type pressurized water reactors (such as heat exchanger tube of steam generators and stainless steel canister material) has been studied. The experiments were carried out in a laboratory model system. During the sorption studies, boric acid coolants provided by the Paks Nuclear Power Plant (Paks NPP) were circulated for a period of 30 h. Solution and tube samples obtained in the course of above experiments were analyzed by independent methods (??- and ??-spectrometry, ICP-MS, SEM-EDX, voltammetry and XPS). The experimental results reveal that: (i) the surface excess of the TRU nuclides studied is extremely low (less than 1% of a monolayer coverage); (ii) the surface excess of uranium species measured on the SG tube surfaces is significantly higher, after 30 h sorption period (??_sample = 1.0 ??g cm^?2 U ? 3.7 × 10^?9 mol cm^?2 UO₂) exceeds a monolayer coverage; (iii) the mechanistic features of the contamination processes (specific or non-specific adsorption, deposition of colloidal and/or disperse particles) depend decisively upon the nature of the studied radionuclides and the chemical structure and composition of the oxide layer formed on stainless steel surfaces.