Volume 61, Number 34, 2016
Theoretical and Mathematical Physics
The Inverse Problem from Discrete 1 States in the D = 1 Dimensional Space R.J. Lombard, R. Yekken, R. Mezhoud Romanian Journal of Physics 61,
301313 (2016)
We propose a method to determine the potential from a discrete spectrum in the D = 1 dimensional space. The key point is given by approximate relationships between the moments of the ground state density and the excitation energies. These relationships are exact in the case of the harmonic oscillator. Empirical correction factors can be used for other potentials, leading to a useful zero order approximation for the moments. From the approximation to the ground state density moments, a first approximated potential is calculated by inversion of the Schrödinger equation. This potential is used to improve the relationships between ground state moments and excitation energies. Convergence towards the exact potential is obtained by iterating the procedure. Conditions for a unique answer are presented. Solving this problem has implications in higher dimensions for potentials separable or partly separable in Cartesian coordinates. The method is illustrated by a few examples.
Φ^{4} Theory is Trivial Renata Jora Romanian Journal of Physics 61,
314319 (2016)
We prove that the Φ^{4} theory is trivial for any values of the bare coupling constant λ thus extending previous results referring to very strong couplings to the full range of values for this parameter. The method is based on all order properties of the partition and two point functions in the path integral formalism. method of functional integration.
Trivial Lagrangians in the Causal Approach D.R. Grigore Romanian Journal of Physics 61,
320332 (2016)
We prove the nonuniqueness theorem for the chronological products of a gauge model. We use a cohomological language where the cochains are chronological products, gauge invariance means a cocycle restriction and coboundaries are expressions producing zero sandwiched between physical states. Suppose that we have gauge invariance up to order n of the perturbation theory and we modify the firstorder chronological products by a coboundary (a trivial Lagrangian). Then the chronological products up to order n get modified by a coboundary also.
Spatially Hyperbolic Universes with Fundamental Matter Sources Adrian Bodnarescu, MarinaAura Dariescu Romanian Journal of Physics 61,
333349 (2016)
Motivated by publications on the signature of negative curvature Universes in the CMB maps, in the present paper, we have analyzed the $k = −1$ − FRW Universe, with different types of mattersources. Thus, the nonrelativistic dust, the false vacuum, the CMB radiation and the stiff matter cases are discussed in order to see the behavior of the Universe characterized by each matter source alone. Finally, we have discussed the Einstein–Gordon Equations for a scalar with spontaneously broken symmetry.
Applications of the Extended Fractional EulerLagrange Equations Model to Freely Oscillating Dynamical Systems Adel Agila, Dumitru Baleanu, Rajeh Eid, Bulent Irfanoglu Romanian Journal of Physics 61,
350359 (2016)
The fractional calculus and the calculus of variations are utilized to model and control complex dynamical systems. Those systems are presented more accurately by means of fractional models. In this study, an extended version of the fractional EulerLagrange equations is introduced. In these equations the damping force term is extended to be proportional to the fractional derivative of the displacement with variable fractional order. The finite difference methods and the Coimbra fractional derivative are used to approximate the solution of the introduced fractional EulerLagrange equations model. The free oscillating single pendulum system is investigated.
Soliton Solutions of the CubicQuintic Nonlinear Schrödinger Equation with Variable Coefficients Houria Triki, AbdulMajid Wazwaz Romanian Journal of Physics 61,
360366 (2016)
In this work, a nonlinear Schrödinger equation with variable coefficients incorporating cubicquintic nonlinearities, selfsteepening, and selffrequency shift is investigated by application of the trial equation method. The model describes the propagation of femtosecond light pulses in optical fibers. Exact solitonlike solutions including bright, dark, and singular solutions are derived. Parametric conditions for the existence of envelope soliton solutions are given.
Conservation Laws for Coupled Wave Equations P. Masemola, A.H. Kara, A.H. Bhrawy, A. Biswas Romanian Journal of Physics 61,
367377 (2016)
This paper reports conservation laws for coupled wave equations that are studied in several contexts. These include twolayered shallow water waves, longshort wave interactions, longitudinal and transverse wave interactions and others. The conserved densities are secured with the aid of Lie symmetry analysis, while the conserved quantities are obtained from the soliton solutions that were reported earlier.
Various Exact Rational Solutions of the Twodimensional Maccari's System Feng Yuan, Jiguang Rao, K. Porsezian, D. Mihalache, Jingsong He Romanian Journal of Physics 61,
378399 (2016)
A general explicit form of rational solutions for the Maccari’s system is given in terms of the Gram determinants by the bilinear method. It is shown that the fundamental rational solutions are made up of the lump and the simplest line rogue wave solutions. Under certain parametric conditions, the lumps can be classified into three patterns: bright, bimodal, and dark states. The fundamental rogue wave is called line rogue wave, because it arises from a constant background with a line profile and then disappears into the same background. The multirational solutions consist of either fundamental lumps or fundamental line rogue waves, or hybrid of lumps and line rogue waves. The multirational solutions also show that the multirogue waves describe the interaction of several fundamental rogue waves, which also arise from the constant background and then decay back to it. Moreover, higherorder rogue waves exhibit quite different patterns, such as bright, dark, and intermediate waveforms.
Nuclear Physics
Heavy Ion Orbiting and Regge Poles (I) F. Carstoiu, M. Lassaut, L. Trache, V. Balanica Romanian Journal of Physics 61,
400412 (2016)
We review the semiclassical theory for heavy ion orbiting insisting on the connection with Regge poles and barriertop resonances. Although the physical content of the phenomenon is well understood semiclassically, a clear signature is hard to be found because the relation between the observation angle and the deflection angle is not one to one.
Calculation of Nuclear Matter in the Presence of Strong Magnetic Field Using LOCV Technique G. H. Bordbar, Z. Rezaei Romanian Journal of Physics 61,
413423 (2016)
In the present work, we are interested in the properties of nuclear matter at zero temperature in the presence of strong magnetic fields using the lowest order constraint variational (LOCV) method employing $AV_{18}$ nuclear potential. Our results indicate that in the absence of a magnetic field, the energy per particle is a symmetric function of the spin polarization parameter. This shows that for the nuclear matter, the spontaneous phase transition to a ferromagnetic state does not occur. However, we have found that for the magnetic fields $B \gtrsim 10^{18}$ G, the symmetry of energy is broken and the energy has a minimum at a positive value of the spin polarization parameter. We have also found that the effect of magnetic field on the value of energy is more significant at the low densities. Our calculations show that at lower densities, the spin polarization parameter is more sensitive to the magnetic field.
NumberProjected Spectroscopic Factor for One Pair of LikeNucleons Transfer Reaction within the Framework of the PicketFence Model Y. Benbouzid, N.H. Allal, M. Fellah Romanian Journal of Physics 61,
424434 (2016)
An expression of the spectroscopic factor for one pair of likenucleons transfer reaction is established by means of the sharpBCS (SBCS) numberprojection method. It includes pairing correlations between likeparticles and the particlenumber fluctuations which are inherent to the BCS theory are eliminated. This expression appears as a limit of a sequence which converges as a function of the extraction degrees of the false components. A numerical study is then performed within the framework of the picketfence schematic model. It is shown that the convergence as a function of the extraction degrees of the false components is rapid. Moreover, it is shown that the projection effect on the spectroscopic factors is nonnegligible. Indeed, the relative discrepancy between the BCS and SBCS values may reach up to 6%. The particlenumber fluctuations which are inherent to the BCS approach must then be taken into account in the calculation of the spectroscopic factor of such reactions.
Atomic Physics
RMatrix Calculation of Singly Ionized Carbon Structure for XRay Laser Modelling C. Iorga, V. Pais, V. Stancalie Romanian Journal of Physics 61,
435444 (2016)
This study presents the results of extensive calculations for the singly ionized carbon ion based on the electron scattering on the C^{2+} ion in the frameworks of the Rmatrix theory. Combining the Rmatrix and Quantum defect theory and method the Rydberg series of resonances have been identified. Comparison with other data has been made. Part of present calculation results includes the oscillator strengths, collision strengths and photoionization cross sections which are further used to benchmark the data needed to perform the population kinetics in plasma. The laserproduced carbon plasma is investigated for Xray emission. Competing processes describing the level population distribution include autoionization, Auger decay and collisional ionization of the outershell electrons by electrons generated during the photoionization.
XRF and MicroPixe as Investigation Tools for Ancient Metallurgy  the Cases of PreMonetary Signs Type "Arrowhead" from Histria and of Agighiol Hoard Daniela CristeaStan, B. Constantinescu, G. Talmatchi, D. Ceccato Romanian Journal of Physics 61,
445456 (2016)
Compositional analysis can identify alloys made by ancient people, help in the authentication of items with uncertain origin (i.e. not excavated from wellcontrolled archaeological environment) and bring information on the employed metallurgical procedures. The main metallurgical problem of ancient bronze alloys was to have a good homogeneous microstructure at least in the range of few microns that means to avoid elemental segregation. If XRay Fluorescence (XRF) analysis gives the general elemental composition (approx. 30 mm^{2} investigated area), microProton Induced Xray Emission (microPIXE) is an excellent tool to investigate the alloys microstructure, especially segregation phenomena. We investigated warfare Scythiandesign arrowheads and premonetary signs type “arrowhead” found in Dobroudja, especially in Histria area, but also in Floriile (a Thracian settlement on Danube), both supposed produced by Histria and by its “barbarian” neighbors (Getae, Scythians). For comparison, we also present a preliminary study on two GetoThracian silver appliqués, part of Agighiol (Northern Dobroudja) hoard.
Condensed Matter
Influence of Randomness on Small Angle Scattering from Deterministic Mass Fractals E.M. Anitas, V.A. Osipov, A.I. Kuklin, A.Yu. Cherny Romanian Journal of Physics 61,
457463 (2016)
We suggest new algorithm for constructing a random mass fractal from a deterministic one. The positions of ”units” inside the fractal are taken at random, while their number is kept constant at each iteration. The smallangle scattering intensity $I(q)$, where $q$ is the scattering vector magnitude, is calculated for a system of randomly oriented fractals with spatially uncorrelated positions. We investigate how the introduced randomness smears the logperiodic function $I(q)q^D$ ($D$ is the fractal dimension) and thus how the scaling factor of fractal can be extracted from the scattering intensity.
Mechanisms of Micropore Formation in Silicone Rubber Based Membranes I. Bica, E.M. Anitas, M. Bunoiu, L. Iordaconiu, C.M. Bortun, L.M.E. Averis Romanian Journal of Physics 61,
464472 (2016)
In this paper we present the fabrication method of microporous membranes based on silicone rubber and stearic acid, at various volume concentrations of the catalyst. During mixing, air dissolves in the liquid solution. Then, during polymerization gas bubbles form and penetrate the membrane. At the end of polymerization, one obtains pores and we show that their dimensional distribution is significantly influenced by the catalyst concentration. We present the obtained results and discuss the influence of catalyst concentration on the pore distribution within the framework of a newly developed theoretical model. The results give new insights into pore formation mechanisms in silicone rubber based membranes.
Magnetic Scattering Determination from Sans Contrast Variation Experiments at IBR2 Reactor M. Balasoiu, A.I. Kuklin Romanian Journal of Physics 61,
473482 (2016)
Separate determination of the nuclear and magnetic contributions to the scattering intensity by means small angle neutron scattering (SANS) method is analyzed. The possibility of simultaneous and separate investigation of nuclear and magnetic structures of a system by means of neutron scattering gives especially valuable the use of neutrons in magnetic materials characterization. The experimental necessity of a magnetic field application during the SANS measurements change the initial state of the colloidal disperse system, unlike in the case of the bulk materials. The SANS method with the use of contrast variation technique for studying the structure of magnetic colloidal particles solve this problem and eliminates the need for a magnetic field application during the measurements.
Structure of WaterBased Magnetic Liquids by SmallAngle XRay Scattering A.V. Nagornyi, V.I. Petrenko, M.V. Avdeev, S.O. Solopan, O.V. Yelenich, A.G. Belous, A.A. Veligzhanin, A.Yu. Gruzinov, Ya.V. Zubavichus, L.A. Bulavin Romanian Journal of Physics 61,
483490 (2016)
Structure of magnetic fluids, which were produced by two methods of synthesis and stabilization of magnetite nanoparticles in aqueous solution of agarose, was considered in the given work. Complex aggregation in the colloidal systems was found according to smallangle synchrotron Xray scattering (SAXS) technique. Effective size of single polydisperse magnetic particles and fractal dimensions of aggregates in ferrofluids were estimated from experiment. Comparative SAXS analysis indicates that the content of agarose in water almost does not affect on structure of magnetic fluids at nanoscale level.
Residual Stress Measurements by Neutron Diffraction at the IBR2 Pulsed Reactor G.D. Bokuchava, I.V. Papushkin, A.V. Tamonov, A.A. Kruglov Romanian Journal of Physics 61,
491505 (2016)
Neutron diffraction is widely used for investigations of residual stresses in various constructional materials and bulk industrial components due to the nondestructive character of the method and high penetration depth of neutrons. Therefore, to study residual stresses, the Fourier stress diffractometer FSD has been constructed at the IBR2 pulsed reactor (Dubna, Russia). Using a special correlation technique high resolution level of the instrument has been achieved: $\Delta d/d \approx 2 \div 4 \cdot10^{3}$ . The FSD design satisfies the requirements of high luminosity, high resolution and specific sample environment. In this paper, the design and current status of FSD diffractometer is reported.
Microstructure and Interphase Magnetic Coupling in Nd2Fe14B/αFe Nanocomposites Obtained by Mechanical Milling and Short Time Annealing Sever Mican, Răzvan Hirian, Léopold V.B. Diop, Ionel Chicinas, Olivier Isnard, Viorel Pop Romanian Journal of Physics 61,
506517 (2016)
The effects of short time annealing and soft phase premilling on the structural and magnetic properties of 6 h milled Nd_{2}Fe_{14}B/10wt% Fe magnetic nanocomposites were investigated. The Xray diffraction peaks of Nd_{2}Fe_{14}B disappeared after milling due to crystal structure damage, this effect being more pronounced when using premilled Fe. After annealing, the characteristic peaks of Nd_{2}Fe_{14}B were restored with a limited growth of the αFe crystallites. The best exchange coupling was obtained for the samples which contain unmilled Fe as the soft phase. The maximum coercive field is 0.61 T. The samples containing premilled Fe have lower coercive field values, but show a higher remanence. The Nd_{2}Fe_{14}B/αFe exchange coupling is analysed.
Method of Obtaining Porous Polymer Structure Using Atmospheric Pressure Plasma B.G. Rusu, V. Pohoata, C. Ionita, R. Schrittwieser, N. Dumitrascu Romanian Journal of Physics 61,
518526 (2016)
This study focuses on producing porous polymer under plasma conditions using two different monomers: ethylene glycol and styrene. A plasma discharge at atmospheric pressure was used to induce polymerisation reactions in order to obtain copolymer films based on the two monomers. The plasma source consists of a dielectric barrier discharge which operates in an argon gas flow with glass as dielectric. The porous polymer was obtained by dissolution and sonication of the hydrophilic groups from the material. The new porous material was tested in terms of protein adsorption. The films were characterized by Fourier Transform infrared spectroscopy, Xray Photoelectron Spectroscopy and Scanning Electron Microscopy techniques.
A New Material for Bipolar Plates Used in Fuel Cells Alexis Negrea, Zorica Bacinschi, Ioan Alin Bucurica, Sofia Teodorescu, Raluca Stirbescu Romanian Journal of Physics 61,
527535 (2016)
The backelitegraphite composite material developed to meet the operating conditions of a proton exchange membrane fuel cells (PEMFC) is obtained from a polymer matrix (Novolac thermorigid resin), the hardener – HMTA and the conductive material – graphite powder. The production method requires size conditioning at 90 °C, stiffening thermal treatment at 120–125 °C and the final crosslinking treatment at 280 °C. All of these parameters influence the electrical and mechanical properties of the material and also can be used in recommendation of material to be involved in bipolar plates manufacturing. For the proposed material it was obtained the values for electrical conductivity of 248 Scm^{1} and flexural strength of 38 MPa.
Study on the Axial Distribution of the Stored Microparticles in an Electrodynamic Trap by Using Software Image Processing O.S. Stoican Romanian Journal of Physics 61,
536542 (2016)
A method aimed to study the properties of a solid particles assembly trapped by an electrodynamic trap is reported. Method is based on the digital processing of the trapped microparticles video image obtained by using a web camera. The algorithm used to derive the trapped microparticles axial density distribution from qualitative information embedded in an image is described.
Effect of Magnesium Oxide Particle Size and the Filler Content on Magnesium Potassium Phosphate Cement Properties M. Nicu, L. Ionascu, F. Dragolici, Gh. Dogaru Romanian Journal of Physics 61,
543552 (2016)
The radioactive aluminium waste generated by the VVRS nuclear reactor decommissioning after nearly 15 years from shutdown is represented as low and intermediate radioactive waste and is divided as activated and contaminated aluminium metal. To realize a conditioning matrix for radioactive aluminum is necessary to study alternative cementitious systems such as magnesium potassium phosphate cement. This paper presents the influence of magnesium oxide and the filler content on properties of magnesium potassium phosphate cement, such as: fluidity, setting time, pH, and compressive strength (in fresh and hardened state). In this study were used two types of MgO with different specific surface area and different types of filler (fly ash and red mud). The mechanical tests for samples of MKPC will be correlated with XRD characterization data. The studies in this paper were carried out on the engineering properties of the resulting paste or mortar and attempted in order to obtain an optimized formula of magnesium potassium phosphate cement based on the raw materials available.
To the Coarsening Mechanism of Pt Nanoparticles During Sintering R.D. Vengrenovich, B.V. Ivanskii, I.I. Panko, A.V. Moskaliuk, S.V. Yarema, V.I. Kryvetskyi, M.O. Stasyk Romanian Journal of Physics 61,
553566 (2016)
A comparison between the generalized ChakravertyWagner and LifshitsSlyozovWagner distributions with experimental histograms for Ptnanocrystals has been performed according to the modified LSW theory applied to the surface (2D) and bulk (3D) systems. Pt nanocrystals were synthesized and deposited onto a plain solid substrate from the gas phase or from the liquid phase on the surface of carbon nanotubes. Good correlation between the experimental histograms and the theoretical curves proves that two mechanisms of the nanocrystals’ growth (dissolution) can be involved simultaneously during the Ostwald ripening stage. One of them is controlled by diffusion, while the chemical reaction rate controls the other mechanism. Details of comparison between the experimental histograms and theoretical curves prove that growth of Ptnanoparticles is controlled mainly by the chemical reaction rate (i.e. Wagner’s mechanism) regardless of the synthesis method and the sintering conditions for nanocrystals.
Design and Testing of Flexible Carbon Nanocomposites for Resistive Force Sensing Applications Leila Zevri, Iulian Iordache, Aristofan Al. Teişanu, Gheorghe Ioniţă Romanian Journal of Physics 61,
567576 (2016)
This paper reports on the research that investigated the obtaining of electrically conducting nanocomposites materials with properties which allow their use as resistive force sensors. The used method consisted in the addition of electrically conductive particles with nanometric dimensions in an elastomer matrix. The samples obtained showed values of electrical volume resistivity as follows: SEKTJ5 ($\rho_v \sim 10^5$ $\Omega\cdot$cm), SEKTJ6 ($\rho_v \sim 10^4$ $\Omega\cdot$cm), SECHB6 ($\rho_v \sim 10^6$ $\Omega\cdot$cm) and for SECHB7 ($\rho_v \sim 10^4$ $\Omega\cdot$cm). It was drawn the chart of electrical resistivity as a function of the concentration of conductive filler material and it was established the percolation transition region (conductivenonconductive transition region) where the nanocomposites show to be very sensitive. The differences in electrical resistivity, that account for the tensile sensitivity of the nanocomposites materials, are explained. According to the applied force, the variations of the electrical resistance were recorded for samples tested in dynamical conditions and it was demonstrated the ability of the nanocomposites materials to quickly respond to almost instantaneous application of a force in the range of (0.5–50) N. It was calculated the tensile sensitivity at a given rate of the applied force, reaching 35566 $\Omega$/N for 1.5 N/s and 50400 $\Omega$/N for 0.5 N/s.
Optics
Nonlinear ParityTimeSymmetry Breaking in Optical Waveguides with Complex GaussianType Potentials Pengfei Li, Bin Liu, Lu Li, Dumitru Mihalache Romanian Journal of Physics 61,
577594 (2016)
Dynamics of Spatial Solitons in ParityTimeSymmetric Optical Lattices: A Selection of Recent Theoretical Results YingJi He, Xing Zhu, Dumitru Mihalache Romanian Journal of Physics 61,
595613 (2016)
We provide a brief overview of selected recent theoretical studies, which were performed in diverse relevant optical settings, on the key features and unique dynamics of spatial solitons in paritytimesymmetric optical lattices.
Analyzing of the Radiation Induced Damage to Optical Glasses by Using Online Heating Laser Measurements MR. Ioan Romanian Journal of Physics 61,
614625 (2016)
Optical glasses are a bridge between the optical systems and the real environment and are often subjected to hostile conditions. The purpose of this work is by applying laser beam techniques to study changes of transparent glass properties induced by their irradiation with strong ionizing radiation (e.g., X, γ radiation). Basically, we investigated the changes due to the color centers or other defects produced by irradiating crownbor glasses with 1.25 MeV gammarays. In principle, we can expect to changes in the transmittance properties of these glasses, but also to the reversing process by heating (estimate the migration energy of defects). Several BK7 glass samples were irradiated using a dose rate of about 0.1 kGy/s ± 5%, at the IFINHH (BucharestMagurele) ^{60}Co irradiation facility. Optical characterizations were performed on a low power HeNe laser beam, before and after passing through each irradiated glass sample. According to the changes in the glass transmittance, the value of the linear dichroism at 296.15 K and 441.83 K was determined for BK7 samples (61.37 % and respectively 43.34 % relative increase). In our case, the experimental setup has highlighted a relative decrease of the initial laser beam power of 65.14 % at 296.15 K on the entire range of absorbed doses (0–24.4) kGy. From the calculus, we obtained the following migration energies: 0.103 eV, 0.38 eV, 0.174 eV, 0.089 eV (Table 1) and 0.161 eV, 0.089 eV, 0.076 eV (Table 2). The measurements were made with the following experimental setup: 25LHP151230 type HeNe laser, Melles Griot, USA; PowerMaxUSB UVVIS type powermeter, Coherent, USA.
Comparative Discussion on Global Models for Optical Properties of BI_{2}O_{3} G. Murariu, A. Dinescu, A.G. Murariu, S. ConduracheBota Romanian Journal of Physics 61,
626637 (2016)
The novelty of this paper is due to the investigation of the possibility of reaching a reliable global effective model of temperature dependence on the optical properties, based on automated neural network (ANN). For this approach, starting with a series of experimental data set of the measured reflectance magnitudes we built and studied 20 different ANN with RBF and MLP structure and with different activation functions of neurons. After the training, validation and test stages, only the best 10 models were retained and a systematic comparison between the simulations results is included in the paper. The discussion is continued with the comparison of ANN approach results obtained for refractive index magnitudes. As in the previous part, after the training, validation and test stages, only the best 10 models were retained and a systematic comparison between the simulations results. The obtained results are promising, but the performance is not higher than in the previous analytical investigation.
Plasma Physics
Correlation Analysis of the Polarization Degree for the Gas Mixture H_{2} Kr C. Gavrila, I. Gruia, A.E. Sandu Romanian Journal of Physics 61,
638647 (2016)
Correlation Analysis it is used to study the intensity of the link between the variables. In this study it has been analysed the correlation of the Polarization Degree (PD), for the mixture of gases H_{2}Kr, (ν_{H2}/ν_{Ne} = 27/38), using the intensities of the chromatic lines (λ_{1} = 758,7 nm, λ_{2} = 760 nm and λ_{3} = 811 nm), measuring at different values of the discharge current, I[mA] at the frequency of 25kHz for different values of the pressure (p_{1} = 27,5 torr, p_{2} = 42 torr, p_{3} = 65 torr and p_{4} = 80 torr).
Infrared and XRay Photoelectron Spectroscopy in Surface Characterization of Polydimethylsiloxane Thin Films Generated on Metallic Substrates in Multipoints to Plane Corona Discharges A. Groza, A. Surmeian, C. Diplasu, C. Negrila, B. Mihalcea, M. Ganciu Romanian Journal of Physics 61,
648656 (2016)
By coupling two spectral techniques, namely, Xray photoelectron and specular reflection infrared spectroscopy at high reflection angles, we identified, in this paper, the formation of SiO_{2} respectively SiO_{x} (1 < x < 2) structures on the surface of polydimethylsiloxane thin films. These layers have been obtained as a result of placing a thin liquid film precursor on a germanium substrate under corona charge injection in multipoints to plane electrodes configuration in air at atmospheric pressure for 2 hours.
QuasiMonochrome Light Polarization Study in Binary ElectropositiveElectronegative Gas Mixture L.C. Ciobotaru, I. Gruia Romanian Journal of Physics 61,
657665 (2016)
The Monochromatizationeffect of light (the Meffect) consists in the reduction of an electronegativeelectropositive gas mixtures discharge emission spectrum to only a few (or even one) spectral lines, in AC/DC discharges at moderate to high total pressure (tens to hundreds of Torr) of the gas mixtures. The paper deals with the emitted quasimonochrome light polarization preliminary study in a hydrogenneon gas mixture related to the experimental conditions: the total pressure of the gas mixture, the partial pressure of the electronegative gas and the discharge current for different frequencies values, proposing also a basic explanation of the phenomenon.
Medical Physics
Comparison of Different Techniques Used to Improve the Sealants Adhesion on Enamel Surface A. Rotaru, T. Teslaru, I. Chirap, A.M. Prodan, N. Dumitrascu Romanian Journal of Physics 61,
666675 (2016)
Traditional approaches to treat caries, in a surgical manner, were replaced by new strategies that focus on preventing disease and preserving intact tooth structure. One of the most efficient methods of teeth decay preventions is the sealing. The success of the sealant application technique on the enamel surface depends on the maintenance of tooth isolation, adequate rinsing and efficient photopolymerization and cooperation with patients (children). The purpose of this research is to improve adhesion of sealants on the enamel surface of tooth by various pretreatment techniques. Posterior teeth, recently extracted for orthodontic reasons, free of caries, were treated by acid – etching, UV radiations and plasma. Plasma was generated in a dielectric barrier discharge with asymmetrical configuration of electrodes, working at atmospheric pressure in helium. The control of plasma parameters was assured by electrical and optical diagnosis and the main surface properties of enamel implied in the sealant adhesion, respectively roughness and wettability, were investigated by atomic force microscopy and contact angle measurements.
Environmental and Earth Physics
Models for Temperature Evolution in Constanta Area (Romania) A. Barbulescu Romanian Journal of Physics 61,
676686 (2016)
Modeling the climatic processes is of big importance for prediction of their future evolution. In this article we present the results of modeling the mean annual temperature series collected at the Constanta (Romania) meteorological station over a period of 41 years, by four different approaches. Firstly, AutoRegressive Moving Average and Gene Expression Programming are employed for obtaining suitable models. Aiming to find robust and accurate ones, we also use a hybrid method that benefits from the advantages of the two previous methods, and that combines the linear patterns discovered with ARMA and the nonlinear patterns treated by GEP. Comparisons are made with the results of Support Vector Regression. The models obtained by the last method gave the best results.
Assessment of Annual Effective Dose Due to the Indoor Radon Exposure in a SecondDegree Earthquake Zone of Kutahya (Turkey) L. Sahin, H. Cetinkaya, S. Gelgun Romanian Journal of Physics 61,
687696 (2016)
Indoor radon concentrations have been measured in 100 dwellings of Central Kutahya, Turkey, using LR115 type II SolidState Nuclear Track Detectors. The detectors were placed in living rooms during the period of MarchMay 2010 for three times. The annual indoor radon concentrations vary from 74.1 ± 2.4 to 272.3 ± 4.2 Bq m^{3}, with a mean value of 120.8 ± 2.0 Bq m^{3}. Based on these results, we find an annual effective dose varying from 1.9 to 6.9 mSv, with a mean value of 3 mSv y^{1} received by inhabitants living in Kutahya city.
Application of the PowerModerate Weighted Mean (PMM) Concept in the Calculation of Reference Values of Interlaboratory Comparisons M. Sahagia, A. Luca, A. Antohe, M.R. Ioan, E. GarciaToraño Romanian Journal of Physics 61,
697706 (2016)
Recently, the Consultative Committee for Ionizing Radiations Section II, Measurement of Radionuclides, of the International Committee of Weights and Measures [CIPMCCRI(II)], decided to apply the new concept of powermoderate weighted mean (PMM) in calculation of the Key Comparison Reference Values(KCRV), standard uncertainties and degrees of equivalence, Document CCRI(II)/1337. The paper will exemplify the calculations of 226 Ra activity concentration of a slag sample, using the PMM mode, for which we had recommended before the use of the weighted mean. This value will also be compared with a recently published one.
Isolation and Identification of Soil Bacteria Able to Efficiently Remove Copper from Culture Mediums M. Constantin, C.D. Negut , C. Barna, C. Cîmpeanu, I.I. Ardelean Romanian Journal of Physics 61,
707717 (2016)
Copsa Mica is one of the sites with the highest degree of heavy metal pollution in Romania, the whole area being well known on national and international level for the ecological lack of balance due to the nonferrous smelter plant. Three bacterial strains were isolated from the soil samples derived from the extraction sit. The growth and development of these bacteria in high concentration of toxic metal environments (Pb, Cd, Zn) represent an important research direction, the understanding of those mechanisms involved in bacterial resistance against the toxic effects of heavy metals and radionuclides contributes to the development of new technologies for treating contaminated water. Concurrently, their capacity of absorbing and accumulating the metals present in a liquid medium was analyzed. In this paper we report the isolation, purification and identification of three bacterial strains from metal contaminated soil (Copsa Mica), strains able to grow in high copper concentration and efficiently remove copper from culture medium. The best removal results were obtained with Bacillus megaterium which removes 99.8 % of the copper present in growth media supplemented with 192 mM Cu^{2+}.
Evaluation of Environmental Monitoring Data at Low and IntermediateLevel Radioactive Waste Repository Baita, Bihor, Romania B.T. Obreja, E. Neacsu, L. Done, F. Dragolici, L. Tugulan, L. Zicman, D. Scradeanu Romanian Journal of Physics 61,
718727 (2016)
In this paper we aim to present a study based on the results obtained in the frame of Environmental Monitoring Programme (EPM) for the Romanian National Repository for Low and Intermediate Radioactive Waste (DNDR) – Baita Bihor from 1998 to 2014. EPM involves the determination of artificial radionuclides activity per unit of mass or volume of samples from soil, vegetation, surface water and sediment, as well as the ambient dose equivalent rate, H^{*} (10) at surface and at 1 m above the ground level . The obtained data were investigated in order to determine the impact of repository activity on population and environment. Our results demonstrate that the facility is operating safely, without any radiological impact to the surrounding environment.
Can We Still Use Classic Seismic Hazard Analysis for Strong and Deep Vrancea Earthquakes? Gheorghe Mărmureanu, Alexandru Mărmureanu, Elena Florinela Manea, Dragos TomaDanila, Mihnea Vlad Romanian Journal of Physics 61,
728738 (2016)
Seismic hazard is quantified by three parameters: level of severity, and spatial and temporal measurements. Thus, the purpose of a seismic hazard assessment is to determine these three parameters from instrumental, historical and geological observations. The characterization of earthquake ground motion for engineering applications generally involves the use of empirical models referred to as groundmotion prediction equations (GMPEs). In classic seismic hazard analysis, this GMPE describes a relationship between a ground motion parameter Y (PGA, PGV, MMI) in site, earthquake magnitude M, sourcesite distance R, and uncertainty or residual δ. Nothing on epicenter ground acceleration (PGA), velocity (PGV), MMI intensity. Selection of a ground motion for engineering design and other considerations requires a clear understanding of seismic hazard among stakeholders, seismologists and engineers in particular. The authors are coming with data in connection to strong and deep Vrancea earthquakes, the large uncertainties of peak ground accelerations (PGA) recorded in epicenter and far of epicenter in extraCarpathian area after last three strong earthquakes (August 30,1986; M_{W} = 7.1; h = 131.4 km; May 30,1990; M_{W} = 6.9; h = 90.9 km; May 31,1990; M_{W} = 6.4; h = 86.9 km). There are many PGA records in Romanian and Republic of Moldavia seismic stations. Many of them are larger than in epicenter Vrâncioaia seismic station. Consequently, classic seismic hazard analysis is not applicable at all to strong and deep Vrancea earthquakes.
