Peripheral interactions of relativistic 14N nuclei with emulsion nuclei

The results of investigation of the dissociation of the 2.86-A-GeV/c ¹⁴N nucleus in an emulsion are presented. The cross sections for various fragmentation channels are given. The invariant approach to analysis of fragmentation is used. The momentum and correlation characteristics of the α particles for the ¹⁴N → 3α + X channel in the laboratory system and c.m.s. of three α particles are examined. The results obtained for the ¹⁴N nucleus are compared with similar data for the ¹²C and ¹⁶O nuclei.     

Synthesis and cytotoxicity of 28-carboxymethoxy lupane triterpenoids.Preference of 28-O-acylation over 28-O-alkylation of betulm by ethyl bromoacetate

28-Carboxymethoxy lupane tritepenoids 3 and 4 were synthesized by alkylation of betulin with the THP protected 2- hydroxyethyl iodide followed by oxidation and reduction.Direct reaction of betulin(5) or betulone(10) with ethyl bromoacetate led to 28-O-acylation,instead of 28-O-alkylation.The targeted compounds 3 and 4 were not cytotoxic at the highest concentration tested(75μmol/L),suggesting that elongation of the chain length at the 28-position in both betulinic acid(1) and betulonic acid(2) was detrim...     

Fragmentation channels of relativistic 7Be nuclei in peripheral interactions

At the JINR Nuclotron, ⁷Li nuclei are accelerated. The charge-exchange reaction involving these nuclei at an external target provides a secondary 1.23-A-GeV ⁷Be beam. This beam is used to irradiate emulsion chambers. The mean free path λ_inel(⁷Be) = 14.0 ± 0.8 cm for inelastic ⁷Be interactions in an emulsion coincides within the errors with those for ⁶Li and ⁷Li nuclei. More than 10% of the ⁷Be events are associated with the peripheral interactions in which the total charge of the relativistic fragments is equal to the charge of the ⁷Be nucleus and in which charged mesons are not produced. An unusual ratio of the helium isotopes is revealed in the composition of the doubly charged fragments of the ⁷Be nuclei: the number of the ³He fragments is twice as large as that of the ⁴He fragments. Each of 50% of peripheral interaction events includes two doubly charged fragments. The channels of the ⁷Be fragmentation into charged fragments are presented. In 50% of events, the ⁷Be fragmentation occurs only into charged fragments without the emission of neutrons. The ⁴He + ³He channel dominates, whereas each of the ⁴He + d + p and ⁶Li + p channels constitutes 10%. Two events without neutron emission are observed in the ³He + t + p and ³He + d + d three-body channels. The mean free path for the coherent dissociation of relativistic ⁷Be nuclei into ⁴He + ³He is equal to 7 ± 1 m. The main features of the fragmentation of relativistic ⁷Be nuclei in such peripheral interactions are explained by the ³He + ⁴He two-cluster structure of the ⁷Be nucleus.     

Luminescence of Ytterbium and Neodymium in Complexes with Bis-Macrocyclic Ligands

We have studied the spectral-luminescent characteristics of ytterbium and neodymium ions in complexes with new polydentate bis-crown-ether and bis-azacyclic ligands both of whose parts are bound by 2,9-substituted 1,10-phenanthroline. The relationship between the intensity, rare-earth ion luminescence lifetime, and the composition of the coordination sphere of the complexes is established. Using the considered compounds as an example, we show the advantage of the joint influence of screening of the central ion from the effect of high-frequency O–H- and C–H vibrations of the solvent molecules and of the photoantenna effect in improvement of the luminescent characteristics of lanthanides.     

Comparative analysis of the electronic structure and electronegativity of groups of unbranched ethers of sulphoxylate acid

Journal of Structural Chemistry - Within the quantum theory of atoms in molecules (QTAIM) the electronic structure of sulphoxylate acid HOSOH and compounds of a homological series of ethers of...     

Dissociation of 10C nuclei in a track nuclear emulsion at an energy of 1.2 GeV per nucleon

The charge topology in the fragmentation of ¹⁰C nuclei in a track nuclear emulsion at an energy of 1.2 GeV per nucleon is studied. In the coherent dissociation of ¹⁰C nuclei, about 82% of events are associated with the channel ¹⁰C → 2α+ 2p. The angular distributions and correlations of product fragments are presented for this channel. It is found that among ¹⁰C → 2α+ 2p events, about 30% are associated with the process in which dissociation through the ground state of the unstable ⁹Be_g.s. nucleus is followed by ⁸Be_g.s. + p decays.     

Ion beam engineered nano silver silicon substrates for surface enhanced Raman spectroscopy

We demonstrate a method for engineering substrates for surface enhanced Raman spectroscopy (SERS) by Ag⁻ ion implantation in Si. The implantation dose and beam current density are chosen such that the Ag concentration in Si exceeds the solid solubility limit, causes aggregation of Ag and nucleates Ag nano particles. The embedded nano particles are then partially exposed by a wet etch process. Our measurements show that the so fabricated nano‐composite substrates are very effective as stable and reproducible SERS substrates. Copyright © 2013 John Wiley & Sons, Ltd.     

The First Observation of 4f-Luminescence in New Heteronuclear Lanthanide–Germanium Complexes

New lanthanide–germanium complexes with diethylenetriaminepentaacetic acid (DTPA) have been synthesized and were characterized by means of elemental analysis, IR-, UV-absorption and luminescent spectroscopy. The 4f-luminescence of heteronuclear Ln(Ge-DTPA)2 (Ln=Sm, Eu, Tb, Dy) complexes in aqueous solutions was investigated for the first time.     

Fragmentation of relativistic nuclei in peripheral interactions in nuclear track emulsion

The technique of nuclear track emulsions is used to explore the fragmentation of light relativistic nuclei down to the most peripheral interactions: nuclear “white” stars. A complete pattern of the relativistic dissociation of a 8B nucleus with target fragment accompaniment is presented. Relativistic dissociation ⁹Be → 2α is explored using significant statistics, and a relative contribution of ⁸Be decays from 0+ and 2+ states is established. Target fragment accompaniments are shown for relativistic fragmentation ¹⁴N → 3He +H and ²²Ne → 5He. The leading role of the electromagnetic dissociation on heavy nuclei with respect to breakups on target protons is demonstrated in all these cases. It is possible to conclude that the peripheral dissociation of relativistic nuclei in nuclear track emulsion is a unique tool to study many-body systems composed of the lightest nuclei and nucleons in the energy scale relevant for nuclear astrophysics. The text was submitted by the authors in English.