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[en] The theory of multistep nuclear reactions due to Feshbach, Kerman and Koonin (1980) is reviewed with particular attention to recent developments. These include the latest analyses of multistep compound and multistep direct reactions that have established the dependence of the effective interaction strength V0 on the incident nucleon energy and on the atomic weight of the target, and the study of P to Q-chain transitions. (Author)
[en] The aim of this work is to examine the possibility of using the peculiarities of the tunnelling evolution to explain subbarrier two-particle transfer and emission enhancement in heavy-ion reactions. First, the authors obtain analytical expressions for the penetration of a quasi-monochromatic wave-packet probability density at any depth inside a rectangular opaque barrier and for effective penetrating velocities at various depths. Then, they present the results of calculations of the average transition and reflection durations inside the barrier. Last, they also present rather simple and physically clear considerations for the development of a new model or a theoretical approach to a subbarrier two-particle transfer and emission enhancement in nuclear collisions, which is an alternative to the Josephson nuclear effect model. 14 refs., 4 figs
[en] The method of high-energy approximation is adapted for the processes of direct (peripheral nucleus-nuclear) interaction. It is based on developing three-dimensional quasi-classics using E >> U and kR >> 1 approximations allowing one to perform calculations of elastic, inelastic scattering amplitudes and reactions of nucleon transfer in an obvious analytical form. A qualitative analysis of these processes' amplitude dependence on potential parameters, energy and pulse transmitted, is given. 8 refs
[en] The main purpose of the FRENA facility is to perform direct measurements. However direct measurements are more tedious and not all reactions particularly those with very low Gamow Energy are feasible without an underground facility. Thus to study intricacies of varied astrophysical reactions, to start with the facility can be utilized for indirect method through the study of resonant elastic scattering, sub-Coulomb transfer reactions, reaction mechanisms of (p,α) and (α,p) reactions etc.
[en] In recent years, one of the major goals of contemporary nuclear physics research is to address the physics of Super Heavy Element (SHE) production. For production of SHE one need to understand the fusion-fission dynamics. It has been proposed to have neutron rich radioactive beams bombarding stable targets to reach the valley of stability of SHE. But heavy ion reaction studies with RIB have lead to observation of new reaction channels such as projectile breakup rather than enhancing cross section for the fusion channel. In general, projectiles with low breakup threshold affect fusion-fission reaction dynamics
[en] Full text: Importin-α (Impα) plays a role in the classical nuclear import pathway, binding to cargo proteins with activities in the nucleus. Different Impα paralogs responsible for specific cargos can be found in a single organism. The cargos contain nuclear localization sequences (NLSs), which are characterized by one or two clusters of basic amino acids (monopartite and bipartite NLSs, respectively). In this work we present the crystal structure of Impα from M. musculus (residues 70-529, lacking the auto inhibitory domain) bound to a NLS peptide (pepTM). The peptide corresponds to the optimal sequence obtained by an oriented peptide library experiment designed to probe the specificity of the major NLS binding site. The peptide library used five degenerate positions and identified the sequence KKKRR as the optimal sequence for binding to this site for mouse Impα (70-529). The protein was obtained using an E. coli expression system and purified by affinity chromatography followed by an ion exchange chromatography. A single crystal of Impα -pepTM complex was grown by the hanging drop method. The data were collected using the Synchrotron Radiation Source LNLS, Brazil and processed to 2.3. Molecular replacement techniques were used to determine the crystal structure. Electron density corresponding to the peptide was present in both major and minor binding sites The peptide is bound to Impα similar as the simian virus 40 (SV40) large tumour (T)-antigen NLS. Binding assays confirmed that the peptide bound to Impα with low nM affinities. This is the first time that structural information has been linked to an oriented peptide library screening approach for importin-α; the results will contribute to understanding of the sequence determinants of classical NLSs, and may help identify as yet unidentified classical NLSs in novel proteins. (author)
[en] The results of the analysis of the α-particle transfer "1"2C(d, "6Li)"8Be and "1"2Be("3He, "7Be)"8Be reactions at the low energies performed within the modified DWBA have been presented. New estimates are obtained for values of the asymptotic normalization coefficients (ANCs) for α+"3He → "7Be (g.s.) and α+"3He → "7Be (E"∗ = 0.429 MeV) as well as of the astrophysical S_3_4(0) factors for the direct capture "3He(α, γ)"7Be reaction.
[en] Angular and energy distributions, as well as integral cross section of inclusion reaction of two-nucleon transfer with participation of three-particle nuclei in intermediate energy range were calculated. 12 refs., 2 figs
[en] α-particle multiplicity in heavy-ion fission is a promising tool to understand the fission dynamics. A precise information about the sources of α-particle emission is very crucial. Dominantly, α particles in heavy-ion fission originate from three sources: (i) pre-scission (compound nucleus), (ii) post-scission (fission fragments), and (iii) near-scission emission (neck region). In the present paper, we report the results obtained for α-particle multiplicity in "1"3C (75 MeV) + "2"3"2Th fission, where α-transfer would lead to "9Be not the "8Be