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The copolymerization of sodium p-styrenesulfonate with styrene is studied in solvents that form homogeneous solutions with mixtures of these monomers and differ in polarity: DMFA, a mixture of 1,4-dioxane with DMF, DMSO, and a DMSO-water mixture. It is shown that the diagrams of the copolymer composition depend on the type of solvent and that their shapes do not obey the Mayo-Lewis model. The copolymers become substantially enriched with styrene units during an increase in the solvent polarity. The main cause of deviation from the classical scheme of binary copolymerization is the selective solvation of growing macroradicals with styrene. This effect becomes more pronounced during an increase in the solvent polarity and a decrease in its dissolving ability with respect to polystyrene and during polymer separation into a heterophase. This conclusion is confirmed by the dependence of the copolymer composition on the initiator concentration.

Mass-energy distributions (MEDs) and capture-fission cross sections have been measured in the reaction 48 Ca + 208 Pb → 256 No at the energies E lab = 206 – 242 MeV using a double-arm time-of-flight spectrometer CORSET. It has been observed that MED of the fragments consists of two parts, namely, the classical fusion–fission process corresponding to the symmetric fission of 256 No and quasi-fission “shoulders” corresponding to the light fragment masses ∼ 60 – 90 u and complimentary heavy fragment masses. The quasi-fission “shoulders” have a higher total kinetic energy (TKE) as compared with that expected for the classical fission. A mathematical formalism was employed for the MEDs fragment decomposition into fusion–fission and quasi-fission components. In the fusion–fission process a high-energy Super-Short mode has been discovered for the masses M H = 130 – 135 u and the TKE of ≈ 233 MeV .

The CORSET time-of-flight spectrometer has been developed at the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research (Dubna, Russia) for investigating binary products of nuclear reactions. The spectrometer has been used to study the dynamics of fusion-fission and quasi-fission of superheavy elements. The design and the main characteristics of the spectrometer, as well as the algorithms for deducing the mass-energy distributions of fragments and the cross sections of nuclear reactions, are presented. The spectrometer contains two time-of-flight arms based on microchannel-plate detectors and three telescopes, each of which is composed of two microchannel-plate detectors and one semiconductor detector. A system of four semiconductor detectors is used to obtain the absolute value of a cross section. The time resolution of the time-of-flight arms is 150 ps, which allows the time-of-flight distances to be set at 10–20 cm, thus providing a mass resolution of 3 amu and an angular resolution of 0.3°. Owing to these characteristics, the spectrometer can be used as a trigger in multidetector setups for measuring light charged particles, neutrons, and γ rays in coincidence with reaction fragments.

Fission fragment mass and energy distributions (MED) and fission fragment folding angle distributions (FFFAD) have been measured in the reaction 6Li + 232Th within the lithium projectile energy range E lab = 28.5 – 62.5 MeV . The values of the ratio between the complete and incomplete fusion cross-sections have been obtained from a combined analysis of MED and FFFAD. The incomplete fusion originates from transfer reactions and/or from the 6Li breakup mainly into α and d clusters. It has been found that the contribution of complete fusion into the total fusion–fission cross-section is only ∼ 27 % at the lithium projectile energy E lab = 28.5 MeV ( ∼ 2 MeV below the Coulomb barrier).

The competition between fusion-fission and quasi-fission in the reactions 48 Ca+ 208 Pb and 48 Ca+ 244 Pu(E * = 40MeV) is investigated using the pre-scission neutron multiciplicity distributions ( PSNMD ) obtained with a new analysis protocol.

M. G. Itkis,∗ ,a A. A. Bogatchev,a I. M. Itkis,a M. Jandel,a J. Kliman,a G. N. Kniajeva,a N. A. Kondratiev,a I. V. Korzyukov,a E. M. Kozulin,a L. Krupa,a Yu. Ts. Oganessian,a I. V. Pokrovski,a V. A. Ponomarenko,a E. V. Prokhorova,a A. Ya. Rusanov,a V. M. Voskresenski,a A. A. Goverdovski,b F. Hanappe,c T. Materna,c N. Rowley,d L. Stuttge,d G. Giardina,e and K. J. Moodyf Flerov Laboratory of Nuclear Research, JINR, 141980 Dubna, Russia Institute for Physics & Power Engineering, 249020 Obninsk, Russia Universite Libre de Bruxelles, 1050 Bruxelles, Belgium Institut de Recherches Subatomiques, F-67037 Strasbourg Cedex, France Dipartimento di Fisica dell’ Universita di Messina, 98166 Messina, Italy University of California, Lawrence Livermore National Laboratory, Livermore, California 94551, USA

For the first time the cross section and angular distributions of fission fragments have been measured for the compound nucleus 220 Ra produced in the reaction 12 C+ 208 Pb at three energy values in the range from 0.5 to 8.0 r MeV below the fusion barrier calculated in terms of the Bass model. In the investigated energy range there is a plateau characterized by the relation W (180°)/ W (90°)=1.2 in the angular anisotropy of fission fragments.

The talk presents the results of an investigation of the main characteristics (mass and energy distributions of fission fragments and multiplicity of neutrons) of the fission of the nuclei of 220 Ra, 226 Th, 256 No, 270 Sg, 286 112 produced in reactions with ions of 18 O, 22 Ne and 48 Ca at energies close to and essentially below the Coulomb barrier. The data obtained show that the form of the mass and energy distributions of the fission fragments of 226 Th and 270 Sg is accounted for by the multimodal nature of the fission. In addition, for 226 Th, a new phenomenon was established there is a significant difference between the numbers of prescission neutrons for symmetric and asymmetric fission modes. It was found that, for the low-energy fission of the nucleus of 286 112, the mass distribution of the fragments is of a clear-cut asymmetric form, contrary to what is observed for the spotaneous fission of the nuclei with Z = 100–104 and for the induced fission of 270 Sg.

The potential to create a remote, contactless, diagnostic method for biological tissues or materials with properties similar to those of biological tissues, so-called phantoms, is studied. The method is based on measurement of local oscillations of the surface of material under study under the action of acoustic and ultrasonic waves. The application of a laser-scanning vibrometer provides a means for visualization oscillations of a biological tissue phantom with model defects in the form of air bubbles, regions with higher density, and laminations, and allows determination of the positions of these defects.

The interest in the study of the fission process of superheavy nuclei mainly deals with the opportunity to obtain information about the cross-section of the compound nucleus (CN) formation at excitation energies E*\approx 15–30 MeV. It allows one to estimate the survival probability of the superheavy composite system after evaporation of 1–3 neutrons, i.e. in "cold" or "warm" fusion reactions. However, in order to solve this problem deeper understanding of the coalescence processes between colliding nuclei, the competition between fusion-fission and quasi-fission processes is needed. The characteristics of both processes, their manifestation in the experimental observables and the relative contribution to the capture cross-section in dependence on the excitation energies, reaction entrance channel etc were investigated for a wide range of target-projectile combinations. Results of the experiments devoted to the study of the fusion-fission and quasi-fission processes in the reactions of the formation of the superheavy nuclei with Z = 102–122 are presented. The heavy ions 26Mg, 48Ca, 50Ti, 58Fe and 64Ni were used as projectiles. The choice of the reactions with 48Ca and actinide-targets was inspired by the experiments on the production of the isotopes 283112, 289114 and 283116 in Dubna using the same reactions. The 50Ti, 58Fe and 64Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia) and the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) using the time-of-flight spectrometer of fission fragments CORSET. The role of the shell effects, the influence of the entrance channel asymmetry and the deformations of colliding nuclei on the mechanism of the fusion-fission and the competitive process of quasi-fission are discussed. The recent results on synthesis of superheavy nuclei and the perspectives of the "hot" fusion reaction for the production of superheavy nuclei are considered.

The mass-energy distributions of the fragments, fusion-fission (OFF) and capture (oCap) cross-sections in the reactions 26Mg+248Cm; 48Ca+2"RPb, 232Th, 238U , 2 4 4 ~ u , 2 4 8 ~ m ; 244Pu, 248Cm were measured at the U400 accelerator of Flerov Laboratory of Nuclear Reactions (JINR, Russia) with use of double-ann time-of-flight spectrometer CORSET. The influence of reaction entrance channel on the competition between fusion-fission and quasi-fission processes was studied. Strong manifestation of the shell effects in mass distributions of fusion-fission and quasi-fission fragments was observed. The multimodal fission phenomena were found for 2 7 4 H ~ and 256N0 nuclei at low excitation energies. % ~ ~ 2 0 8 p b , 232~h

Results of the experiments aimed at the study of fission and quasi‐fission processes in the reactions 12C+204Pb, 48Ca+144,154Sm, 168Er, 208Pb, 238U, 244Pu, 248Cm; 58Fe+208Pb, 244Pu, 248Cm, and 64Ni+186W, 242Pu are presented. The choice of the above‐mentioned reactions was inspired by the experiments on the production of the isotopes 283112, 289114 and 283116 at Dubna using the same reactions. The 58Fe and 64Ni projectiles were chosen since the corresponding projectile‐target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U‐400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia), the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) and the Accelerator of the Laboratory of University of Jyvaskyla (JYFL, Finland) using the time‐of‐flight spectrometer of fission fragments CORSET and the neutron multi‐detector DEMON. The role of shell effects and the influence of the entrance channel asymmetry and the deformatio...

The process of fusion-fission of heavy and superheavy nuclei (SHE) with Z = 82-122 formed in the reactions with ^48Ca and ^58Fe ions at energies near and below the Coulomb barrier has been studied. The experiments were carried out at the ^400U accelerator of the Flerov Laboratory of Nuclear Reactions (JINR) and at the XTU Tandem accelerator of the National Laboratory of Legnaro, (LNL) using the time-of-flight spectrometer of fission fragments CORSET and the neutron multi-detector DEMON. As a result of the experiments, mass and energy distributions (MED) of fission fragments, fission, quasi-fission and evaporation residues cross sections, multiplicities of neutrons and gamma quanta and their dependence on the mechanism of formation and decay of compound systems have been studied.

Flerov Laboratory of Nuclear Reactions, JINR, 141980 Dubna, Russia I Universite Libre de Bruxelles, Bruxelles, Belgique 21nstitut de Recherches Subatomiques, CNRS-IN2P3, Strasbourg, France 'Department of Physics, University of Messina and INFN, Italy "Institute of Nuclear Physics of the National Nuclear Center of Kazakhstan 480082 Almaty, Kazakhstan 'Institute of Physics SASc, 84228 Bratislava, Slovakia

Results of fission fragment mass-energy distributions of the compound ${}^{226}\mathrm{Th}$ nucleus formed in the sub-barrier fusion reaction ${}^{18}\mathrm{O}{+}^{208}\mathrm{Pb}$ at an energy of ${}^{18}\mathrm{O}$ ions ${E}_{\mathrm{lab}}=78$ MeV are reported. The reaction has been studied twice using two different accelerators, and both sets of experimental data agree quite well. Performed analysis of the experimental data with the use of a new multicomponent method has shown that alongside the well-known modes, i.e., the symmetric (S) and two asymmetric modes standard-one and standard-two, a high-energy mode standard-three has manifested itself. The last named mode appears due to the influence of the close-to-sphere neutron shell with $N\ensuremath{\approx}50$ in the light fission fragment group. Theoretical calculations of the prescission shapes of the fissioning nuclei ${}^{224,226}\mathrm{Th}$ confirm this conclusion.

Mass-energy distributions of the ${}^{220}\mathrm{Ra}$ fission fragments produced in the ${}^{12}\mathrm{C}{+}^{208}\mathrm{Pb}$ reaction at projectile energies higher and deep below the Coulomb barrier have been measured using a two-arm time-of-flight spectrometer CORSET. It has been shown that an asymmetric component appears at the sides of the prevailing symmetric fission with a cooling of the compound nucleus. The component consists of two standard modes with average masses of $\ensuremath{\simeq}132$ and $\ensuremath{\simeq}139.$ A three-component structure has also been observed in the total kinetic energy distributions in the range of asymmetric fission fragment masses.

The fusion-fission reactions {sup 22}Ne + {sup 248}Cm and {sup 22}Ne + {sup 249}Cf were investigated at projectile energies equal to 102 and 127 MeV. Mass-energy distributions and yields are shown. Two-dimensional plots of TKE vs fragment mass are also shown for {sup 48}Ca reactions at 230 MeV with {sup 208}Pb and {sup 238}U, leading to {sup 256}No and {sup 286}112.

The neutron spectra associated to the two fission modes of Th-226 have been measured in coincidence with the fragment yields of the O-18 + Pb-208 reaction at E-lab = 78 MeV. The pre- and post-fission multiplicities and temperatures have been extracted. Surprisingly, the prefission neutron multiplicities associated with the asymmetric mode are larger than those associated with the symmetric mode.

The talk presents new results obtained in the study of fission of superheavy nuclei 256No, 270Sg and 286112 formed in reactions with 22Ne and 48Ca ions at energies near or considerably lower than the Coulomb barrier. The experiments have been performed at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (FLNR) with the use of the time-of-flight spectrometer of fission fragments CORSET.

Osteogenesis imperfecta (OI) is a disease with biochemical evidence of abnormality in collagen biosynthesis. We report here that expression of the OI phenotype extends to the level of dermal fibroblast morphology in vitro. Growth characteristics and morphology of control (n = 3) and 01 cell strains (n = 10) were compared. Our results show that (1) OI fibroblasts take longer time (16 days) than that with control cells (13 days) to reach stationary phase; (2) OI fibroblasts achieve a lower cell density (1.0 +/- 0.09) at stationary phase compared to control cells (1.47 +/- 0.1); p0.01; (3) cell shape (expressed as the width/length ratio) was also abnormal in OI cells: they have significantly increased ratios (p0.05) compared to control. These changes were associated with an increased level of fibronectin concentration and engorged cytoplasmic vesicles in dermal fibroblasts in vitro. We have reason to suspect that dysmorphology of fibroblasts may be related to aberrant collagen metabolism that leads to inadequacy of extracellular substratum, that in its turn hinders normal adhesion of cells as well as their spreading, morphology and fibronectin concentration.

Lymphadenosis NK/LY resistant to rubomycin was obtained on its repeated cultivation in mice treated with the antibiotic. The rubomycin resistance was stable and preserved for a long period of time when the line was repeatedly cultivated in mice not exposed to the antibiotic. The tumor cells resistant to rubomycin acquired resistance to olivomycin. DNA histograms of the tumor cells obtained by means of impulse cytophotometry provided determination of the tumor sensitivity and resistance to antitumor agents. It is recommended that impulse cytophotometry be used for the screening of antitumor drugs and development of their administration regimen.

A total of 52-fold passages of leukemia L-1210 were carried out for a year on mice treated intraperitoneally with olivomycin. Prolonged exposure to olivomycin resulted in decreased transplantability of the tumor cells. The tumor cells obtained under the effect of olivomycin were more sensitive (collateral sensitivity) to methotrexate as compared to the cells of the initial strain L-1210. An intramuscular route for transplantation of the tumor cells of leukemia L-1210 is recommended. The dosage intramuscular transplantation of the tumor cells provided simultaneously data on transplantability, tumor size and lifer-time of mice.