On the residual properties of link groups

We study the residual properties of finitely generated linear groups. Using the methods under consideration, we prove the residual 2-finiteness of the groups of the Whitehead link, the Borromean links (answering a question of Cochran), and some other links. We show also that each link is a sublink of some link whose group is residually 2-finite.     

Data on light-fragment correlations in 40 Ar + 58 Ni at 77 MeV/nucleon

Results of the experimental study of p ⁴ He, d ³ He, dT, pT, p ³ He and, for the first time, nT, n ³ He, n ⁴ He correlations in the region of small relative momenta are presented. The data analysis provides an estimate of the effective source size or emission time.Received: 26 May 2003, Published online: 2 December 2003PACS: 25.70.Pq Multifragment emission and correlations     

A size effect in the optical properties of powdered TiO2

The spectral reflectivity ρ in the region 0.36–2.1 μm and its change Δρ with irradiation by 30 keV electrons versus the average grain sizer _av in a TiO₂ (rutile) powder has been studied in the range 1–7.5 μm. It has been established that the dependence of ρ onr _av differs for different regions of the spectrum, but there is a common increase of ρ in the size range 2.5–4 μm. The value of Δρ after irradiation is also less in powders with this range of sizes. It has been shown that the dependence Δρ=f(r _av) with increasing electron fluence from 2·10¹⁵ to 4·10¹⁶ is strengthened for one band and weakened for another. Tomsk Polytechnic University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 41, No. 12, pp. 52–58, December, 1998.     

ESR study of low-temperature radiolysis and photolysis of substitutedN′-furfurylidenebenzhydrazides

Low-temperature (77 K) γ- and UV irradiation of substitutedN′-furfurylidenebenzhydrazides produces paramagnetic particles in radiation-chemical yields of (0.05–0.5)/100 eV and quantum yields of 4·10⁻⁵–10⁻³, respectively. ESR study showed that hydrazyl radicals and HC·O and N·O₂ are the main products of radiolysis and photolysis, and the latter decay upon heating of the sample to 190 K, whereas the hydrazyl radicals survive up to 423 K. Further heating results in thermodestruction of the hydrazides, and the ESR spectrum exhibits only a singlet with splitting at 1 mT, which is characteristic of polyconjugated compounds. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2078–2082, November, 1999.     

Coulomb deexcitation and nonresonant charge exchange of muonic hydrogen in mixtures of hydrogen isotopes

The process of inelastic collisions of excited muonic hydrogen has been considered in the framework of the asymptotic theory of nonadiabatic transitions. The Coulomb deexcitation and chargetransfer rates are calculated in the energy range 0.001–100 eV taking into account the electron-screening effect for excited states in the range n = 3–10 for various isotopic configurations. The text was submitted by the authors in English.     

Interaction of single-walled carbon nanotubes with sulfuric acid

An increase in the radiation yield of paramagnetic centers in H₂SO₄ + nanotubes (NTs) solutions was evidence of the sensitizing influence of NTs on the low-temperature radiolysis of sulfuric acid, that is, on excitation energy and charge transfer. Under the conditions selected, the influence of NTs extended to distances of 100–300 nm. The presence of NTs also influenced the interstice nanodiffusion of atomic hydrogen by decreasing kinetic heterogeneity of the vitrified matrix surrounding NTs. No chemical interaction between atomic hydrogen and carbon NTs was observed at 77–120 K. The diffusion of radical-base anions occurred following the vacancy mechanism and was independent of the presence of NTs. Nanotubes did not form a separate phase as sulfuric acid solutions were cooled to 77 K. The transition from the vitreous to supercooled liquid state was observed as irradiated and nonirradiated solutions were heated to 175 K; no phase transitions occurred over the temperature range 180–300 K. For the first time, substantial changes in the electronic spectra of sulfuric acid solutions of NTs with time were observed: an intense additional absorption band at 320 nm appeared in the spectra in several days. This band was supposedly related to the formation of complexes between H₂SO₄ molecules and the surface of NTs.     

Dynamical effects on the way to fusion of very heavy nuclei

The central collision of ⁴⁰Ar and ²⁰⁸Pb is studied considering the ellipsoidal deformations and isovector dipole mode of motion in the approaching phase. The collective energy dissipation is suggested to originate from the Fermi surface deformation which is treated as a kinematically independent mode of motion within the canonical Lagrange-Rayleigh dynamics. The possible extensions of the approach are discussed. The potential energy surface, calculated using the generalized (folded) surface potential, is studied. The saddle point in the potential energy surface lying at the border of strongly deformed compact configurations is located. The potential energy at this point is about 10MeV smaller than that of the ions touching each other in the spherical shape. The examination of trajectories followed by the system in its evolution shows that the inertia forces strongly hinder the motion of ions along the potential energy valley. The collective energy dissipated during the approach is found to be smaller than the difference in the potential energies at saddle point and at the touching configuration of unpolarized ions.