Simulation of irradiation of thin layers of biological matter by low-energy photon radiation

Passage of 1–400 keV photons through thin layers (0.001–1.0 mm) of biological matter was simulated. Monte Carlo simulation was performed using the GEANT4.9 software package. The energy dependences of the absorbed dose and number of ionizing events and the number of ionizing events per unit absorbed dose were obtained. It was shown that the dependences in many respects are determined by the thickness of layers. Assuming that equal numbers of ionizing events in the layer cause equal biological effects, energy dependences of relative biological effectiveness of photons in the energy range studied have been estimated.     

Stationary phase corrections in the process of bosonization of multi-quark interactions

The functional integration over the auxiliary bosonic variables of cubic order related with the effective action of the Nambu–Jona–Lasinio model with ’t Hooft term has recently been obtained in the form of a loop expansion. Even numbers of loops contribute to the action, while odd numbers of loops are assigned to the measure. We consider the two-loop corrections and analyse their effect on the low-lying pseudoscalar and scalar mass spectra, quark condensates and weak decay constants. The results are compared to the leading order calculations and other approaches. PACS 12.39.Fe, 11.30.Rd, 11.30.Qc     

Traresonator formation of submicron periodic structures

To whom correspondence should be addressd.     

Production of carbon nanotubes by self-propagating high-temperature synthesis

Carbon nanotubes are prepared by the method of self-propagating high-temperature synthesis for the first time. The initial components for this synthesis are carboniferous materials (soda, limestone, and Teflon) and reducers (magnesium, lithium, and sodium) with addition of a nickel or iron catalyst. The morphology of the nanotubes (straight multiwall nanotubes apparently free of a catalyst, bent nanotubes completely filled with a catalyst, and carbon nanofibers) is similar to that of nanotubes grown by chemical methods. The nanotubes account for 2–4 wt % of the product synthesized.     

The continuum gauge field-theory model for low-energy electronic states of icosahedral fullerenes

The low-energy electronic structure of icosahedral fullerenes is studied within the field-theory model. In the field model, the pentagonal rings in the fullerene are simulated by two kinds of gauge fields. The first one, non-abelian field, follows from so-called K spin rotation invariance for the spinor field while the second one describes the elastic flow due to pentagonal apical disclinations. For fullerene molecule, these fluxes are taken into account by introducing an effective field due to magnetic monopole placed at the center of a sphere. Additionally, the spherical geometry of the fullerene is incorporated via the spin connection term. The exact analytical solution of the problem (both for the eigenfunctions and the energy spectrum) is found.     

Self-organization in film nucleation in the high-T c superconductor Y-Ba-Cu-O system

The process of new-phase nucleation in the YBa₂Cu₃O_7−x system deposited by magnetron sputtering has been studied. The first experimental observation of the phenomenon of temporal self-organization in the course of new-phase formation, which was predicted theoretically,^1–3 is reported. Auto-oscillations in the number of nuclei of various chemical compounds 20–60 nm in size were observed to occur within the 15 to 300-s time interval, the total number of nuclei varying aperiodically from 10¹³ m⁻² to less than 10¹¹ m⁻². Fiz. Tverd. Tela (St. Petersburg) 39, 216–218 (February 1997)     

πa1 Transitions and low-energy limit in the linear sigma model

Joint Institute for Nuclear Research, Dubna. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 86, No. 3, pp. 385–390, March, 1991.