Relativistic Nuclear Energy Density Functionals: adjusting parameters to binding energies

We study a particular class of relativistic nuclear energy density functionals in which only nucleon degrees of freedom are explicitly used in the construction of effective interaction terms. Short-distance (high-momentum) correlations, as well as intermediate and long-range dynamics, are encoded in the medium (nucleon density) dependence of the strength functionals of an effective interaction Lagrangian. Guided by the density dependence of microscopic nucleon self-energies in nuclear matter, a phenomenological ansatz for the density-dependent coupling functionals is accurately determined in self-consistent mean-field calculations of binding energies of a large set of axially deformed nuclei. The relationship between the nuclear matter volume, surface and symmetry energies, and the corresponding predictions for nuclear masses is analyzed in detail. The resulting best-fit parametrization of the nuclear energy density functional is further tested in calculations of properties of spherical and deformed medium-heavy and heavy nuclei, including binding energies, charge radii, deformation parameters, neutron skin thickness, and excitation energies of giant multipole resonances.Comment: 53 pages, 23 figures, accepted for publication in Physical Review

Occupational diseases in workers from a smelting and metal works in Varaždin

Daje se pregled uvjeta rada u ljevaonici i tvornici armatura s posebnim osvrtom na izmjerenu buku pri obavljanju pojedinih poslova i izloženost prašini sa sadržajem slobodnog silicijeva dioksida. Nakon toga izloženi su podaci za 14 radnika u kojih je utvrđena pneumokonioza s osvrtom na poslove i zadatke koje su obavljali, subjektivne smetnje, spirometrijski nalaz, rendgenski nalaz pluća i ocjenu radne sposobnosti. Upozorava se na poteškoće u raspoređivanju radnika sa pneumokoniozom i preostalom radnom sposobnošću na druge odgovarajuće poslove.Working conditions in a smelting and metal works, particularly exposure to noise and to dusts containing free silica, are described. Medical histories of 14 workers suffering from pneumoconiosis are analysed and data are correlated with workplaces, signs and symptoms of the disease, and with spirometric and X-ray findings. The workers\u27 residual working capacity was assessed, and problems encountered in assigning the workers to suitable workplaces are stressed

Generalized time-dependent generator coordinate method for small and large amplitude collective motion

An implementation of the generalized time-dependent generator coordinated method (TD-GCM) is developed, that can be applied to the dynamics of small and large amplitude collective motion of atomic nuclei. Both the generator states and weight functions of the GCM correlated wave function depend on time. The initial generator states are obtained as solution of deformation constrained self-consistent mean-field equations, and are evolved in time by the standard mean-field equations of nuclear density functional theory (TD-DFT). The TD-DFT trajectories are used as a generally non-orthogonal and overcomplete basis in which the TD-GCM wave function is expanded. The weights, expressed in terms of a collective wave function, obey a time-dependent GCM (integral) equation. In this explorative study, the generalized TD-GCM is applied to the excitation energies and spreading width of giant resonances, and to the dynamics of induced fission. The necessity of including pairing correlations in the basis of TD-DFT trajectories is demonstrated in the latter example.Comment: 30 pages,11 figure

Localization and clustering in the nuclear Fermi liquid

Using the framework of nuclear energy density functionals we examine the conditions for single-nucleon localization and formation of cluster structures in finite nuclei. We propose to characterize localization by the ratio of the dispersion of single-nucleon wave functions to the average inter-nucleon distance. This parameter generally increases with mass and describes the gradual transition from a hybrid phase in light nuclei, characterized by the spatial localization of individual nucleon states that leads to the formation of cluster structures, toward the Fermi liquid phase in heavier nuclei. Values of the localization parameter that correspond to a crystal phase cannot occur in finite nuclei. Typical length and energy scales in nuclei allow the formation of liquid drops, clusters, and halo structures.Comment: 6 pages, 3 figure

Generalized time-dependent generator coordinate method for small and large amplitude collective motion (II): pairing correlations and fission

The generalized time-dependent generator coordinate method (TD-GCM), developed in the first part of this work and applied to small and large amplitude collective motion in nuclei, is here extended to include pairing correlations. The correlated GCM nuclear wave function is expressed in terms of time-dependent generator states and weight functions. The particle-hole channel of the effective interaction is determined by a Hamiltonian derived from an energy density functional, while pairing is treated dynamically in the standard BCS approximation with time-dependent pairing tensor and single-particle occupation probabilities. With the inclusion of pairing correlations, various time-dependent phenomena in open-shell nuclei can be described more realistically. The model is applied to the description of saddle-to-scission dynamics of induced fission. The generalized TD-GCM charge yields and total kinetic energy distribution for the fission of $^{240}$Pu, are compared to those obtained using the standard time-dependent density functional theory (TD-DFT) approach, and with available data.Comment: 24 pages,9 figures. arXiv admin note: text overlap with arXiv:2304.1336

Nuclear Pairing from Chiral Pion-Nucleon Dynamics: Applications to Finite Nuclei

The 1S0 pairing gap in isospin-symmetric nuclear matter and finite nuclei is investigated using the chiral nucleon-nucleon potential at the N3LO order in the two-body sector, and the N2LO order in the three-body sector. To include realistic nuclear forces in RHB (Relativistic Hartree Bolgoliubov) calculations we rely on a separable form of the pairing interaction adjusted to the bare nuclear force. The separable pairing force is applied to the analysis of pairing properties for several isotopic and isotonic chains of spherical nuclei.Comment: 13 pages, 3 figures, submitted to PR

Effects of synthesis parameters on structure and properties of the ceramic/polymer films based on bacterial cellulose

Cellulose, as the main constituent of plants, is the most common natural material that is widely used. Bacterial cellulose (BC) is a polymer of β-1,4-glucan chains, extracellularly attached to bacterial cells. It possesses the same structure as plant cellulose but its application has many advantages. BC has tinner threads, better crystallinity, mechanical strength and higher purity. By the means of micro- and nano-pores in the structure, it is possible to retain nano particles and enhance the application of obtained nanostructures. BC lacks antibacterial and antioxidative activity, conductivity and magnetic properties, which lowers the possibility of its application in biomedicine and electronics. To overcome previously mentioned deficiency, it is possible to apply bioactive polymers, nanomaterials or solid particles into the structure. High biocidal potential of TiO2 originates from its photocatalytic properties, and the generation of reactive oxygen species (ROS). At the first site of action, they cause cell membrane damage and afterwards, they attack intracellular components causing cell death. Hydroxyapatite (HAp) is capable to act synergistically with TiO2 and to accelerate its efficiency. Having in mind all characteristics of previously mentioned components, we have investigated the structure, morphology, mechanical properties and antimicrobial activity of advanced ceramics/polymer films. The influence of synthesis duration on BC structure, produced by Komagataeibacter xylinus species, was investigated. Thereafter, the possibility of TiO2/HAp ceramic nanocomposite application in BC was examined. The developed structures were analyzed by SEM and EDS analyzes, as well as XRD and FTIR spectroscopy. Mechanical properties were investigated as well

Antibacterial potential of electrochemically exfoliated graphene sheets

Electrochemically exfoliated graphene is functionalized graphene with potential application in biomedicine. Two most relevant biological features of this material are its electrical conductivity and excellent water dispersibility. In this study we have tried to establish the correlation between graphene structure and its antibacterial properties. The exfoliation process was performed in a two electrode-highly oriented pyrolytic graphite electrochemical cell. Solution of ammonium persulfate was used as an electrolyte. Exfoliated graphene sheets were dispersed in aqueous media and characterized by atomic force microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, X photoelectron spectroscopy, X-ray diffraction, electron paramagnetic resonance, zeta potential, contact angle measurements and surface energy. Antibacterial assays have shown lack of the significant antibacterial activity. Major effect on bacteria was slight change of bacteria morphology. Membrane remained intact despite significant change of chemical content of membrane components.This is the peer reviewed version of the paper: Marković, Z. M., Matijašević, D. M., Pavlović, V. B., Jovanović, S. P., Holclajtner-Antunović, I. D., Špitalský, Z., Mičušik, M., Dramićanin, M. D., Milivojević, D. D., Nikšić, M. P., & Todorović Marković, B. M. (2017). Antibacterial potential of electrochemically exfoliated graphene sheets. Journal of Colloid and Interface Science, 500, 30–43. [https://doi.org/10.1016/j.jcis.2017.03.110][https://www.sciencedirect.com/science/article/abs/pii/S0021979717303776?via%3Dihub

Halos and related structures

The halo structure originated in nuclear physics but is now encountered more widely. It appears in loosely bound, clustered systems where the spatial extension of the system is significantly larger than that of the binding potentials. A review is given on our current understanding of these structures, with an emphasis on how the structures evolve as more cluster components are added, and on the experimental situation concerning halo states in light nuclei.Comment: 27 pages, 3 figures, Contribution to Nobel Symposium 152 "Physics With Radioactive Beams

Density dependent hadron field theory for neutron stars with antikaon condensates

We investigate $K^-$ and $\bar K^0$ condensation in $\beta$-equilibrated hyperonic matter within a density dependent hadron field theoretical model. In this model, baryon-baryon and (anti)kaon-baryon interactions are mediated by the exchange of mesons. Density dependent meson-baryon coupling constants are obtained from microscopic Dirac Brueckner calculations using Groningen and Bonn A nucleon-nucleon potential. It is found that the threshold of antikaon condensation is not only sensitive to the equation of state but also to antikaon optical potential depth. Only for large values of antikaon optical potential depth, $K^-$ condensation sets in even in the presence of negatively charged hyperons. The threshold of $\bar K^0$ condensation is always reached after $K^-$ condensation. Antikaon condensation makes the equation of state softer thus resulting in smaller maximum mass stars compared with the case without any condensate.Comment: 20 pages, 7 figures; final version to appear in Physical Review