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Papers by Gheorghe E Draganescu
METHODS: The laser microspectral analysis device LMA-1 (Carl Zeiss, Jena), equipped with a diffra... more METHODS: The laser microspectral analysis device LMA-1 (Carl Zeiss, Jena), equipped with a diffraction spectrometer PGS-2 (Carl Zeiss, Jena). This laser have a resonator with glass doped Nd3+. The output energy of the laser is 0.5-1.2 Joule/pulse λ=1060 nm. The LMA-1 system has mirror lens 40x, used to visualise the explored surface, which can be interchanged with 10 X lens,
Fifth International Conference on Lasers in Medicine: Biotechnologies Integrated in Daily Medicine, 2014
ABSTRACT The present study aims to assess the pulp vitality before and after different tooth blea... more ABSTRACT The present study aims to assess the pulp vitality before and after different tooth bleaching procedures, in order to determine the changes in pulpal microcirculation and whether they are reversible or not. Twelve volunteers were included in this study. For each volunteer, the pulpal blood flow of maxillary teeth was assessed prior to treatment using Laser Doppler Flowmetry. The "in office" bleaching technique was used 6 anterior teeth, with two different gels, a conventional one chemically activated (Group I 3teeth) and another one activated using Nd:YAG laser (Group II-3 teeth). The bleaching agents were applied on counterpart teeth and, after obtaining a esthetic results for each tooth, the pulpal blood flow was assessed using Laser Doppler Flowmetry immediately after treatment and then after one day and one week. All data were collected and statistically analyzed. Immediately after treatment, the assessment showed an increase of pulpal blood flow, for both study groups, but higher in Group I as compared to Group II (p<0.005). The subsequent assessments showed a reduction of the pulpal blood flow with non - significant differences between the study groups (p<0.005).The results suggest that the tooth bleaching procedurere presents a safe treatment method, which does not lead to irreversible damage to the dental pulp, when used correctly.
Advanced Materials Research, Dec 13, 2013
ABSTRACT
Lasers in Dentistry XIV, 2008
The microleakage at the interface between the metal infrastructure and the veneering part of the ... more The microleakage at the interface between the metal infrastructure and the veneering part of the fixed partial dentures are a common problem of aesthetic dentistry. It is possible to use the method of laser microspectral analysis for investigations of microleakage at the metal-veneering material interfaces in fixed partial prostheses. The laser microspectral analysis device LMA-10 (Carl Zeiss, Jena) was used equipped with a diffraction spectrometer PGS-2 (Carl Zeiss, Jena). Different fixed partial dentures were used to determine the microleakage between the metal infrastructure and the veneering material. The distribution of chemical elements at interface infiltration was investigated, making a series of craters and establishing the spectra of the vapours emitted from the craters. Data was gathered in various tables of chemical elements showing the quality and the quantity of microleakage. The laser microspectral analysis is a punctual method of analysis, which allows to investigate small quantities of materials of around 0.1 µg. This method allows to establish the content of atoms and molecules and to perform semi-quantitative and quantitative analysis. By this method it is possible to establish trace elements, i. e. with concentration of ppm (parts per million).
Key Engineering Materials, 2014
ABSTRACT
Advanced Materials Research, 2013
ABSTRACT
Lasers in Dentistry XIV, 2008
The method of laser micro spectral analysis is a method of punctual method of analysis, which per... more The method of laser micro spectral analysis is a method of punctual method of analysis, which permits to investigate small quantity of material, around 0.1 mug. This method permits to establish the content of atoms and molecules. The method permits to make semi-quantitative and quantitative analysis. By this method it is possible to establish trace elements, with concentration of order ppm (parts per million). For atomic UV spectral analysis, intense spectra are produced by the transitions of the metals. The halogens have poor spectra in the UV region. The method is low cost and can be made also with devices adapted for this kind of measurement. By this method we established the curves of concentration distribution for Ca, Mg, P and Zn. These distributions are different of the direction amalgam-nerve duct and on a perpendicular direction to the direction amalgam-nerve duct. We must underline that the method of laser micro spectral analysis gives the possibility to measure the infiltration of due substances in the porous regions of filled tooth.
In this paper is introduced a nonlinear fractional oscillator and is established the solution wit... more In this paper is introduced a nonlinear fractional oscillator and is established the solution with the aid of variational iteration method. It is introduced a useful method for identification of parameters of a vibrating system with fractional damping. The method is based on the wavelet multiresolution analysis and can be used to identify the systems with one or many degrees of freedom.
This paper introduces a nonlinear fractional model to describe the metal diffusion phenomena prod... more This paper introduces a nonlinear fractional model to describe the metal diffusion phenomena produced by electrolytic coating. To simplify the problem, is detailed the case of a one-dimensional diffusion process. This model is in accord with the fractal properties of the roughness of their surfaces.
Advanced Materials Research, 2014
... The tensile tests were realized on a testing machine, equipped with a furnace for controlling... more ... The tensile tests were realized on a testing machine, equipped with a furnace for controlling thetesting temperature. The results of study show that TiNi (50.6 at. % Ni) shape memory alloy is suitable for producing both self-expandable stents, and superelastic stents. ...
Stomatoloski glasnik Srbije, 2004
ABSTRACT
Physica A: Statistical Mechanics and its Applications, 2008
This paper presents a search over adequate quantitative parameters in order to reflect the speech... more This paper presents a search over adequate quantitative parameters in order to reflect the speech quality alteration due to the incorrect positioning of a dental mounting. The research is based on signal analysis.These parameters are extracted from the short time Fourier transform (STFT) and wavelet transform. The paper also investigates the possibility of using the Shannon entropy of the signal as a quantitative parameter.For the investigation the /sh/ and /s/ sounds (phonemes) were used.
Journal of Physics: Conference Series, 2008
ABSTRACT A useful nonlinear identification technique applied to the anelastic and rheologic model... more ABSTRACT A useful nonlinear identification technique applied to the anelastic and rheologic models is presented in this paper. First introduced by Feldman, the method is based on the Hilbert transform, and is currently used for identification of the nonlinear vibrations.
Journal of Mathematical Physics, 1997
The operator algebras of a new family of relativistic geometric models of the relativistic oscill... more The operator algebras of a new family of relativistic geometric models of the relativistic oscillator [1] are studied. It is shown that, generally, the operator of number of quanta and the pair of the shift operators of each model are the generators of a non-unitary representation of the so(1, 2) algebra, except a special case when this algebra becomes the standard one of the non-relativistic harmonic oscillator.
Zeitschrift für Physikalische Chemie, 1996
The European Physical Journal B, 2006
. The quantum covariances of physically transparent pairs of observables relative to two dimers ... more . The quantum covariances of physically transparent pairs of observables relative to two dimers hosted in a solid matrix are exactly investigated in the temporal domain. Both dimers possess fermionic and bosonic degrees of freedom and are dipolarly coupled. We find out and describe clear signatures traceable back to the presence and persistence of quantum coherence in the time evolution of
Applied Mechanics and Materials, 2013
ABSTRACT
Journal of Optics B: Quantum and Semiclassical Optics, 2000
METHODS: The laser microspectral analysis device LMA-1 (Carl Zeiss, Jena), equipped with a diffra... more METHODS: The laser microspectral analysis device LMA-1 (Carl Zeiss, Jena), equipped with a diffraction spectrometer PGS-2 (Carl Zeiss, Jena). This laser have a resonator with glass doped Nd3+. The output energy of the laser is 0.5-1.2 Joule/pulse λ=1060 nm. The LMA-1 system has mirror lens 40x, used to visualise the explored surface, which can be interchanged with 10 X lens,
Fifth International Conference on Lasers in Medicine: Biotechnologies Integrated in Daily Medicine, 2014
ABSTRACT The present study aims to assess the pulp vitality before and after different tooth blea... more ABSTRACT The present study aims to assess the pulp vitality before and after different tooth bleaching procedures, in order to determine the changes in pulpal microcirculation and whether they are reversible or not. Twelve volunteers were included in this study. For each volunteer, the pulpal blood flow of maxillary teeth was assessed prior to treatment using Laser Doppler Flowmetry. The "in office" bleaching technique was used 6 anterior teeth, with two different gels, a conventional one chemically activated (Group I 3teeth) and another one activated using Nd:YAG laser (Group II-3 teeth). The bleaching agents were applied on counterpart teeth and, after obtaining a esthetic results for each tooth, the pulpal blood flow was assessed using Laser Doppler Flowmetry immediately after treatment and then after one day and one week. All data were collected and statistically analyzed. Immediately after treatment, the assessment showed an increase of pulpal blood flow, for both study groups, but higher in Group I as compared to Group II (p<0.005). The subsequent assessments showed a reduction of the pulpal blood flow with non - significant differences between the study groups (p<0.005).The results suggest that the tooth bleaching procedurere presents a safe treatment method, which does not lead to irreversible damage to the dental pulp, when used correctly.
Advanced Materials Research, Dec 13, 2013
ABSTRACT
Lasers in Dentistry XIV, 2008
The microleakage at the interface between the metal infrastructure and the veneering part of the ... more The microleakage at the interface between the metal infrastructure and the veneering part of the fixed partial dentures are a common problem of aesthetic dentistry. It is possible to use the method of laser microspectral analysis for investigations of microleakage at the metal-veneering material interfaces in fixed partial prostheses. The laser microspectral analysis device LMA-10 (Carl Zeiss, Jena) was used equipped with a diffraction spectrometer PGS-2 (Carl Zeiss, Jena). Different fixed partial dentures were used to determine the microleakage between the metal infrastructure and the veneering material. The distribution of chemical elements at interface infiltration was investigated, making a series of craters and establishing the spectra of the vapours emitted from the craters. Data was gathered in various tables of chemical elements showing the quality and the quantity of microleakage. The laser microspectral analysis is a punctual method of analysis, which allows to investigate small quantities of materials of around 0.1 µg. This method allows to establish the content of atoms and molecules and to perform semi-quantitative and quantitative analysis. By this method it is possible to establish trace elements, i. e. with concentration of ppm (parts per million).
Key Engineering Materials, 2014
ABSTRACT
Advanced Materials Research, 2013
ABSTRACT
Lasers in Dentistry XIV, 2008
The method of laser micro spectral analysis is a method of punctual method of analysis, which per... more The method of laser micro spectral analysis is a method of punctual method of analysis, which permits to investigate small quantity of material, around 0.1 mug. This method permits to establish the content of atoms and molecules. The method permits to make semi-quantitative and quantitative analysis. By this method it is possible to establish trace elements, with concentration of order ppm (parts per million). For atomic UV spectral analysis, intense spectra are produced by the transitions of the metals. The halogens have poor spectra in the UV region. The method is low cost and can be made also with devices adapted for this kind of measurement. By this method we established the curves of concentration distribution for Ca, Mg, P and Zn. These distributions are different of the direction amalgam-nerve duct and on a perpendicular direction to the direction amalgam-nerve duct. We must underline that the method of laser micro spectral analysis gives the possibility to measure the infiltration of due substances in the porous regions of filled tooth.
In this paper is introduced a nonlinear fractional oscillator and is established the solution wit... more In this paper is introduced a nonlinear fractional oscillator and is established the solution with the aid of variational iteration method. It is introduced a useful method for identification of parameters of a vibrating system with fractional damping. The method is based on the wavelet multiresolution analysis and can be used to identify the systems with one or many degrees of freedom.
This paper introduces a nonlinear fractional model to describe the metal diffusion phenomena prod... more This paper introduces a nonlinear fractional model to describe the metal diffusion phenomena produced by electrolytic coating. To simplify the problem, is detailed the case of a one-dimensional diffusion process. This model is in accord with the fractal properties of the roughness of their surfaces.
Advanced Materials Research, 2014
... The tensile tests were realized on a testing machine, equipped with a furnace for controlling... more ... The tensile tests were realized on a testing machine, equipped with a furnace for controlling thetesting temperature. The results of study show that TiNi (50.6 at. % Ni) shape memory alloy is suitable for producing both self-expandable stents, and superelastic stents. ...
Stomatoloski glasnik Srbije, 2004
ABSTRACT
Physica A: Statistical Mechanics and its Applications, 2008
This paper presents a search over adequate quantitative parameters in order to reflect the speech... more This paper presents a search over adequate quantitative parameters in order to reflect the speech quality alteration due to the incorrect positioning of a dental mounting. The research is based on signal analysis.These parameters are extracted from the short time Fourier transform (STFT) and wavelet transform. The paper also investigates the possibility of using the Shannon entropy of the signal as a quantitative parameter.For the investigation the /sh/ and /s/ sounds (phonemes) were used.
Journal of Physics: Conference Series, 2008
ABSTRACT A useful nonlinear identification technique applied to the anelastic and rheologic model... more ABSTRACT A useful nonlinear identification technique applied to the anelastic and rheologic models is presented in this paper. First introduced by Feldman, the method is based on the Hilbert transform, and is currently used for identification of the nonlinear vibrations.
Journal of Mathematical Physics, 1997
The operator algebras of a new family of relativistic geometric models of the relativistic oscill... more The operator algebras of a new family of relativistic geometric models of the relativistic oscillator [1] are studied. It is shown that, generally, the operator of number of quanta and the pair of the shift operators of each model are the generators of a non-unitary representation of the so(1, 2) algebra, except a special case when this algebra becomes the standard one of the non-relativistic harmonic oscillator.
Zeitschrift für Physikalische Chemie, 1996
The European Physical Journal B, 2006
. The quantum covariances of physically transparent pairs of observables relative to two dimers ... more . The quantum covariances of physically transparent pairs of observables relative to two dimers hosted in a solid matrix are exactly investigated in the temporal domain. Both dimers possess fermionic and bosonic degrees of freedom and are dipolarly coupled. We find out and describe clear signatures traceable back to the presence and persistence of quantum coherence in the time evolution of
Applied Mechanics and Materials, 2013
ABSTRACT
Journal of Optics B: Quantum and Semiclassical Optics, 2000