EFFECT OF TRANSPLANTATION OF IMMUNOCOMPETENT CELLS TREATED WITH CAFFEINE ON THE PARAMETERS OF THE NERVOUS SYSTEM FUNCTIONAL ACTIVITY

It was demonstrated that in vitro treatment with caffeine splenocytes of mice (CBAxC57Bl / 6) F1 with a passive type of behavior in «open field» modifies the functional activity of these cells, manifested in changes in spontaneous and induced cytokine production; the intravenous injection of these cells is accompanied by modulation of the parameters of the motor and exploratory activity of recipients, the nature of which depends on the dose of caffeine. At the same time were shown some changes in the synthesis of cytokines by brain cells of mice-recipients. Possible mechanisms for modulating effect of transplanted immune cells on recipient's behavior were discussed

Evaporation and fission decay of (132)Ce compound nuclei at E(x)=122 MeV: some limitations of the statistical model

Light charged particle (LCP) emission in the evaporation residue (ER) and fusion fission (FF) channels have been studied for the 200 MeV 32S + 100Mo reaction, leading to 132Ce composite nuclei at E x =122 MeV. The main goal was to study the decay of 132 Ce on the basis of an extended set of observables, to get insights on the fission dynamics. The proton and alpha particle energy spectra, their multiplicities, ER-LCP angular correlations, ER and FF angular distributions, and ER and FF cross-sections were measured. The measured observables were compared with the Statistical Model (SM). Using standard parameters, the model was able to reproduce only the pre-scission multiplicities and the FF and ER cross-sections. The calculation was observed to strongly overestimate the proton and alpha particle multiplicities in the ER channel. Disagreements were also observed for the ER-LCP correlations, the LCP energy spectra and the ER angular distribution. By varying the SM input parameters over a wide range of values, it is shown that it is not possible to reproduce all the observables simultaneously with a unique set of parameters. The inadequacy of the model in reproducing the ER particle multiplicities is also observed analysing data from the literature for other systems in the A ≈ 150 and E x ≈ 100−200 MeV region. These results indicate serious limitations about the use of the SM in extracting information on fission dynamics

Fusion-fission and quasifission of superheavy systems with Z = 110 – 116 formed in Ca 48 -induced reactions

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Fission of 180,182,183Hg and 178Pt nuclei at intermediate excitation energies

Purpose: The study of asymmetric and symmetric fission of 180,182,183Hg and 178Pt nuclei as a function of their excitation energy and isospin. Methods: Mass-energy distributions of fission fragments of 180Hg, 178Pt (two protons less than 180Hg), and 182Hg (two neutrons more than 180Hg) formed in the 36Ar+144Sm,142Nd, and 40Ca+142Nd reactions were measured at energies near and above the Coulomb barrier. Fission of 183Hg obtained in the reaction of 40Ca with 143Nd was also investigated to see if one extra neutron could lead to dramatic changes in the fission process due to the shape-staggering effect in radii, known in 183Hg. The measurements were performed with the double-arm time-of-flight spectrometer CORSET. Results: The observed peculiarities in the fission fragment mass-energy distributions for all studied nuclei may be explained by the presence of a symmetric fission mode and three asymmetric fission modes, manifested by the different total kinetic energies and fragment mass splits. The yield of symmetric mode grows with increasing excitation energy of compound nucleus. Conclusions: The investigated properties of asymmetric fission of 180,182,183Hg and 178Pt nuclei point out the existence of well-deformed proton shell at Z≈36 and a less deformed proton shell at Z ≈ 46.peerReviewe

Asymmetric and symmetric fission of excited nuclei of 180,190Hg and 184,192,202Pb formed in the reactions with 36Ar and 40,48Ca ions

Background: Observation of asymmetric fission of 180Hg has led to intensive theoretical and experimental studies of fission of neutron-deficient nuclei in the lead region. Purpose: The study of asymmetric and symmetric fission modes of 180,190Hg and 184,192,202Pb nuclei. Methods: Mass-energy distributions of fission fragments of 180,190Hg and 184Pb formed in the 36Ar+144,154Sm and 40Ca+144Sm reactions, respectively, at energies near the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET and compared with previously measured 192,202Pb isotopes produced in the 48Ca+144,154Sm reactions. The mass distributions for 180,190Hg and 184,192,202Pb together with old data for 187Ir, 195Au, 198Hg, 201Tl, 205,207Bi, 210Po, and 213At [J. Nucl. Phys. 53, 1225 (1991)] have been decomposed into symmetric and asymmetric fission modes. The total kinetic-energy distributions for different fission fragment mass regions have been analyzed for 180,190Hg and 184Pb. Results: The stabilization role of proton numbers at Z≈36, 38, Z≈45, 46, and Z=28/50 in asymmetric fission of excited preactinide nuclei has been observed. The high (≈145−MeV) and the low (≈128−MeV) energy components have been found in the total kinetic-energy distributions of 180,190Hg fission fragments corresponding to the fragments with proton numbers near Z≈46 and Z≈36, respectively. In the case of fission of 184Pb only the low-energy component (≈135MeV) for the fragments with masses corresponding to the proton numbers Z≈36 and 46 has been found. Conclusions: The studied properties of asymmetric fission of 180,190Hg and 184,192,202Pb nuclei point out the existence of well deformed proton shell at Z≈36 and less deformed proton shell at Z≈46.peerReviewe

Evidence of quasifission in the 180Hg composite system formed in the 68Zn + 112Sn reaction

For the 68Zn + 112Sn reaction the Coulomb parameter Z1Z2 is equal to 1500 that is close to the threshold value for the appearance of quasifission process. It was found that mass-energy distributions of the reaction fragments differ significantly from those obtained in the 36Ar + 144Sm reaction leading to the formation of the same composite system of 180Hg at similar excitation energies of about 50 MeV. In the case of the reaction with 68Zn ions, the mass distribution of fissionlike fragments has a wide two-humped shape with maximum yields at 70 and 110 u for the light and heavy fragments, respectively, instead of 80 and 100 u observed in the fission of 180Hg formed in the 36Ar + 144Sm reaction. The difference is explained by an unexpectedly large contribution (more than 70%) of quasifission in the case of the 68Zn + 112Sn reaction

Inverse quasifission in the reactions Gd 156,160 + W 186

Background: Low-energy multinucleon transfer reactions may be used for production of new neutron-enriched heavy nuclei. Purpose: Our aim is to investigate the influence of proton (Z=82) and neutron (N=82, 126) shells as well as orientation effects on the formation of reaction products in the inverse quasifission process in the reactions 156,160Gd + 186W. Methods: Mass, energy, and angular distributions of primary binary fragments formed in the reactions 156Gd+186W at an energy of 878 MeV, and 160Gd+186W at 860 and 935 MeV, have been measured using the double-arm time-of-flight spectrometer CORSET at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions (FLNR) at the Joint Institute for Nuclear Research (JINR), Dubna. Results: Enhancement in the yield of products with masses 200–215 u has been found for both reactions. The cross sections of the formation of trans-target fragments with masses around 208 u are found to be about 10μb at the Coulomb barrier energy and reach the level of 0.5 mb at the energy above the barrier for side-to-side collision. Conclusions: The enhanced yield of products with masses heavier than the target mass confirms the important role of the closed shells at Z=82 and N=82, 126 in the inverse quasifission process in low-energy damped collisions. The orientation effect caused by the strong deformation of colliding nuclei can result in a gain in the yield of heavy target-like fragments