In this work we propose a universal action for gravity and matter which in first orders leads to standard gravity and QFT theories. In our theory matter acts as conformal factors of generic conformal transformations applied to the metric. In this framework we derived easily the Schwarzschild metric with cosmological constant and the Reissner-Nordstrom metric. Moreover we estimate the value of the cosmological constant in very good agreement with the natural value.

Two exactly-solvable confined models of the completely positive oscillator-shaped quantum well are proposed. Exact solutions of the position-dependent mass Schrödinger equation corresponding to the proposed quantum well potentials are presented. It is shown that the discrete energy spectrum expressions of both models depend on certain positive confinement parameters. The spectrum exhibits positive equidistant behavior for the model confined only with one infinitely high wall and nonequidistant behavior for the model confined with the infinitely high wall from both sides. Wavefunctions of the stationary states of the models under construction are expressed through the Laguerre and Jacobi polynomials. In general, the Jacobi polynomials appearing in wavefunctions depend on parameters $a$ and $b$, but the Laguerre polynomials depend only on the parameter $a$. Some limits and special cases of the constructed models are discussed.

In this paper, an integrable shallow water wave equation with timedependent coefficients in (1+1)-dimensions is taken into account. Through employing the generalized three-wave methods, a series of (double) solitary wave solutions and periodic (solitary) wave solutions to the considered equation are presented with the aid of symbolic calculation. Furthermore, by specifying relevant functions and parameters, the localized structures of some resulting solutions are displayed via some figures. These results enrich the diversity of nonlinear waves in physics.

In this study, we investigate the lump solutions for both integrable (2+1)- and (3+1)-dimensional extended KdV and KP equations using symbolic computation with Maple and the Hirota bilinear (HB) form. For each integrable model, we create positive quadratic function solutions to the HB equation. Graphs of the derived lump solutions are displayed with the proper parameter values.

The electron-impact dissociative ionization of pyridine has been investigated using mass spectrometry. Thirty-two well-resolved mass peaks have been identified in the cation mass spectra and assigned to the most likely ionic molecular fragments. The new sixteen ionic fragments' appearance energies have been determined, and sixteen others remeasured. The total cross-section for electron-impact ionization of pyridine has been measured at 100 eV. Thorough analysis indicates that at least three peaks' groups in the mass spectra occur via the shake-off dehydrogenation mechanism, i.e., by sequential hydrogen atoms elimination from the pyridine parent cation or its fragmentation products. The nature of this process is deciphered.

Combinations of three pairs of contacting media with linear, exponential, and parabolic profiles of dielectric permittivity are described theoretically. Three new types of narrowly localized transverse electric waves propagating along the interfaces between the considered graded-index media are found. The exact dispersion equations for each type of the waves determining the effective refractive index in dependence on optical and geometric characteristics are obtained. The influence of the thicknesses of the graded-index layers on dispersion equation solutions is analyzed. It is found that the effective refractive index increases with an increase in the thickness of the graded-index layers in all considered combinations of the contacting media. The thickness of the parabolic graded-index profile has the least significant effect on the effective refractive index, compared to the linear and exponential ones.

The formation of one-dimensional nanostructures (nanowhiskers) during the evaporation of a drop of C₇₀ fullerene solution in ortho-xylene on a smooth surface of a glass substrate was studied. The growth mechanisms of fullerene nanostructures were analyzed, as well as their morphological and size characteristics were determined.

We develop an $1/n$ expansion method for the systematic approximation of the solutions of classical spin systems (tri-dimensional vectors) which can describe general spin-spin interactions and phases with complex magnetization pattern. This method is applied to study the phase transitions observed in pyrochlore crystals (e.g. Gd₂Ti₂O₇) and the results have qualitative agreement with the experimental ones.

External beam radiotherapy for cervical cancer using 3D conformal radiotherapy (3D-CRT) is a standard procedure in Romania. A dosimetric planning comparison between 3D-CRT and intensity modulated techniques evaluating both target parameters and organs at risk could justify the implementation of the latter techniques in clinical settings. 50 cervical cancer patients were treated with 3D-CRT, and equivalent plans simulated with IMRT and VMAT for a comparative dosimetric assessment. In addition to providing better compliance and homogeneity, intensity modulated techniques provide superior protection for organs at risk, especially for bowel bag, influencing patients’ quality of life.

Due to the the multitude of composite materials available, choosing the most adequate ones is a difficult task. Apart from most relevant characteristics such as aesthetics and mechanical strength, it is just as important to obtain smooth restorations, given the negative effects of bacterial plaque retention on the stomatognathic system. We have considered four of the composite resins most frequently used by dentists in Romania and we used laboratory tests to analyse the wear resistance and surface roughness after applying 3 finishing systems. We show that finishing systems have a powerful impact on composite materials roughness, and the best results are obtained with a microhybrid composite. As for wear resistance, nanohybrid composites proved to be superior to microhybrid ones. The results of the study suggest that the structure of the composite material counter-balances its roughness. From a clinical perspective, the quality of the surface of dental restorations is important not only functionally, preventing their wear and bacterial plaque retention, but also from an aesthetical point of view.

In this paper low background high-resolution gamma spectrometry was used for the determination of the activity concentrations of the natural and man-made radionuclides in topsoil samples collected in the vicinity of a large steel plant in Galati, Romania. Their values (mean ± standard deviation) for ²³⁸U, ²²⁶Ra, ²³²Th, ²³⁵U, ²¹⁰Pb, ⁴⁰K and ¹³⁷Cs were: 38.1 ± 6.2; 35.9 ± 5.4; 35.5 ± 3.0; 1.8 ± 0.4; 47.3 ± 8.6; 504.5 ± 38.9 and 7.2 ± 4.7 Bq·kg^–1, respectively. ⁶⁰Co and ²⁴¹Am had activities below the detection limit: 0.6–1.3 and 2.2–4.7 Bq·kg^–1, respectively. The results indicate inputs of natural radionuclides in the sites close to the slag dump, raw materials transportation facility, ore and coal processing factories, blast furnaces, and iron scrap deposit. The evaluation of the associated radiological impact was performed based on selected hazard parameters: absorbed gamma dose rate, total external gamma dose rate, radium equivalent activity index, external hazard index, representative level index, annual effective dose, excess lifetime cancer risk, and annual gonadal dose.

The seismic recordings from certain types of buildings in urban areas during moderate earthquakes from Vrancea-intermediate depth focal region are processed and analysed. One of the most important element in hazard evaluation at national level is the seismic recording network which has been upgraded in the last years up to over 20 strong motion accelerometers in Bucharest and 135 in Romania with easy data handling (accelerations easy to transform in displacements). The general behaviour of reinforced concrete buildings in Bucharest Metropolis during destructive seismic events from Vrancea-intermediate depth focal region is briefly described. The analysis of the elastic response spectra is made for four buildings subjected to the two recent earthquakes with magnitude higher than 4.8, of October 28, 2018 and January 31, 2020 from Vranceaintermediate depth seismic zone. The information consisting in maximum level of the pseudo-acceleration to which the buildings were subjected may be used to detect and quantify any exceedance of the code spectra of interest in near real-time. The recorded earthquakes data are transmitted in real time to the National Data Centre. The goal is to develop and implement modern techniques and tools able to estimate the effect of earthquakes on the built environment in the shortest time possible after a major earthquake.

The main purpose of this study is to create a database that correlates the data from the current catalogue of Romanian earthquakes (ROMPLUS) with the information from other available catalogues, research studies for the events produced between 984 and 1899, historical documents, and mentions in archives or historical papers. The database will contain, in addition to the ROMPLUS available information, the type of event (tectonic or anthropic) and the references attached to each event. In the second step of our analysis (events recorded after 1900), the database will be updated and connected with the catalogue of the earthquake mechanisms.

Effective decontamination is crucial for managing radioactive waste, and it is important to find optimal practices that consider factors such as ease of use, reduction in secondary waste, and hazardous nature of the material. The study evaluates a chemical decontamination gel effectiveness in removing radioactive materials from commonly used materials at IFIN-HH. Artificially contaminated materials were tested, and the gel decontamination factor was evaluated. The gel has advantages such as easy application, high decontamination factor, and minimal contamination of radioactive materials, making it a promising method for efficient and safe management of radioactive waste.

Zirconium alloys are used in heavy water-cooled reactors due to their low thermal neutron capture cross-section and good mechanical and corrosion properties. At the beginning of their operation, hydrogen was identified as an embrittlement agent. The source of the embrittlement was hydride precipitates that formed as platelets. Hydrides were associated with the cracks and the process was called Delayed Hydride Cracking – DHC. This research aims to develop a reproducible procedure concerning DHC K_IH parameter measurements on Zirconium claddings, by using the Pin Loading Test (PLT) technique. Experimental activities including sample preparation, adding hydrogen, testing and results are presented in detail.