Isfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126Applied physics-I: Introduction to neurophysicsApplied physics-I: Introduction to neurophysics347371115810.18869/acadpub.ijpr.15.4.347FARKhanbabaieMTabeshJournal Article20191126In recent years, many physics departments have turned from pure physics into applied physics so that physics is no longer taught as a major in undergraduate or graduate studies without any specific application. This is due to the physics solutions brought for researchers in different disciplines, and that is for the analytical skills of physicists. From the first differential equation developed by Hodgkin and Huxley for action potential of neurons in brain and nervous system, to suggestion of nanotechnology by Richard Feynman are all fundamental solutions introduced by fundamental sciences, especially physics, to industries, health sciences, and researchers in various fields. In this review paper we try to introduce the position of Neurophysics as a sub-branch of biophysics to physics students and researchers so that we can elaborate the importance of engaging with the international community and training of students of physics according to the day applications. We start with an introduction of central nervous system from the perspective of physics, and then explain the fundamental laws and equations of neurophysics. At the end we will finish with an introductory level of the physical science behind learning and memory.In recent years, many physics departments have turned from pure physics into applied physics so that physics is no longer taught as a major in undergraduate or graduate studies without any specific application. This is due to the physics solutions brought for researchers in different disciplines, and that is for the analytical skills of physicists. From the first differential equation developed by Hodgkin and Huxley for action potential of neurons in brain and nervous system, to suggestion of nanotechnology by Richard Feynman are all fundamental solutions introduced by fundamental sciences, especially physics, to industries, health sciences, and researchers in various fields. In this review paper we try to introduce the position of Neurophysics as a sub-branch of biophysics to physics students and researchers so that we can elaborate the importance of engaging with the international community and training of students of physics according to the day applications. We start with an introduction of central nervous system from the perspective of physics, and then explain the fundamental laws and equations of neurophysics. At the end we will finish with an introductory level of the physical science behind learning and memory.https://ijpr.iut.ac.ir/article_1158_901ba9da74f4814da80a4b08e6dc7d46.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126Damping length of slow magneto-acoustic waves in the coronal loops observed by SDODamping length of slow magneto-acoustic waves in the coronal loops observed by SDO373381115910.18869/acadpub.ijpr.15.4.373FAAAbediniTAmirhosseiniJournal Article20191126Slow magneto-acoustic waves are often observed in polar plumes and active region fan loops. The observed periodicities of these waves are in the range of 1- 40 minutes. Mainly, the ratio of damping time to the oscillation period is less than 2 (equal to the ratio damping length to the wave length), which corresponds to the strong damping regime. In general, slow magneto-acoustic waves can be damped with different dissipation mechanisms. Previously, the effect of thermal conduction like compressive viscosity, optical thin radiation, density stratification, and non-uniform magnetic field on the damping of slow magneto acoustic wave was investigated.
Theoretical studies indicate that the observed damping length of slow waves must be depended to the frequency of oscillation. In this paper, damping length and frequency-dependent damping length in propagating slow magneto-acoustic waves has been studied by AIA/SDO images in the 171 and 193 A0. The results of this analysis indicate that the frequencies range of intensity oscillation is 0.5 to 16.7 mHz (1 to 33 minutes), and power spectral densities of intensity oscillation are dominated for 1, 2.2 3.6 and 4.6 mHz. The average damping length of intensity oscillation was obtained 38.1, 35.4, 32.7 and 29.5 Mm for 1, 2.2, 3.6 and 4.6 mHz oscillation respectively. Also, the damping length of 2.2, 3.6 and 4.6 mHz oscillation was decreased about 7%, 13.5% and 22.2% compared to the damping length of 1 mHz.The order of magnitude of the damping lengths that obtained from this analysis are in agreement with previous findings by the authors and the result of the theoretical dispersion of relations of MHD waves, but the frequency-dependent damping length is much less than the theoretical prediction.Slow magneto-acoustic waves are often observed in polar plumes and active region fan loops. The observed periodicities of these waves are in the range of 1- 40 minutes. Mainly, the ratio of damping time to the oscillation period is less than 2 (equal to the ratio damping length to the wave length), which corresponds to the strong damping regime. In general, slow magneto-acoustic waves can be damped with different dissipation mechanisms. Previously, the effect of thermal conduction like compressive viscosity, optical thin radiation, density stratification, and non-uniform magnetic field on the damping of slow magneto acoustic wave was investigated.
Theoretical studies indicate that the observed damping length of slow waves must be depended to the frequency of oscillation. In this paper, damping length and frequency-dependent damping length in propagating slow magneto-acoustic waves has been studied by AIA/SDO images in the 171 and 193 A0. The results of this analysis indicate that the frequencies range of intensity oscillation is 0.5 to 16.7 mHz (1 to 33 minutes), and power spectral densities of intensity oscillation are dominated for 1, 2.2 3.6 and 4.6 mHz. The average damping length of intensity oscillation was obtained 38.1, 35.4, 32.7 and 29.5 Mm for 1, 2.2, 3.6 and 4.6 mHz oscillation respectively. Also, the damping length of 2.2, 3.6 and 4.6 mHz oscillation was decreased about 7%, 13.5% and 22.2% compared to the damping length of 1 mHz.The order of magnitude of the damping lengths that obtained from this analysis are in agreement with previous findings by the authors and the result of the theoretical dispersion of relations of MHD waves, but the frequency-dependent damping length is much less than the theoretical prediction.https://ijpr.iut.ac.ir/article_1159_0c2a433293b0dfebca1cadf1b0c71c19.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126Dependence of electronic conductance of a carbon nanoring on the position of contacts and the applied magnetic fieldDependence of electronic conductance of a carbon nanoring on the position of contacts and the applied magnetic field383389116010.18869/acadpub.ijpr.15.4.383FAMMardaaniHRabaniFMoghadasiJournal Article20191126In this paper, we studied the electronic conductance of a carbon nanoring using Green’s function method at the tight-binding approach for different positions of contacts in the presence and absence of magnetic field. The results show that as the conductors approch in the nanoring, the tunneling conductance in the gap region improves. Moreover, applying the magnetic field dramatically influences the conductance spectrum of the nanoring so that the existence of the magnetic field causes the configurations with coinciding conductance to be disarticulated. The study of the carbon nanoring including binary benzene rings indicates that the variation of the position of these benzene rings in the nanoring shifts the positions of anti-resonances in the conductance spectrum.In this paper, we studied the electronic conductance of a carbon nanoring using Green’s function method at the tight-binding approach for different positions of contacts in the presence and absence of magnetic field. The results show that as the conductors approch in the nanoring, the tunneling conductance in the gap region improves. Moreover, applying the magnetic field dramatically influences the conductance spectrum of the nanoring so that the existence of the magnetic field causes the configurations with coinciding conductance to be disarticulated. The study of the carbon nanoring including binary benzene rings indicates that the variation of the position of these benzene rings in the nanoring shifts the positions of anti-resonances in the conductance spectrum.https://ijpr.iut.ac.ir/article_1160_fcea578b5bf80d8c69472432aafb1585.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126Investigation of positronium formation by molecular hydrogen ion impact with multiple scattering formulation in charge transfer channelInvestigation of positronium formation by molecular hydrogen ion impact with multiple scattering formulation in charge transfer channel391399116110.18869/acadpub.ijpr.15.4.391FASAmiriFShojaeiRFathiJournal Article20191126In the present work the first and second order scattering amplitudes and the related phase were calculated in the charge transfer channel. The positronium formation, with the impact of molecular hydrogen ion, has been carried out using multiple channel scattering formulation and transition matrix. The calculation of differential cross section has been done by varying the scattering angle from 0 to 180 in the fixed orientation of the molecule. In the next calculation the scattering angles were fixed while the spatial molecular orientation was varied. At last the calculated differential cross section was compared with available results in the literature. The scattering angle spanned from 0 to 180 degrees in the second order nuclear and electronic terms were calculated while the molecular orientation was assumed to be fixed. Otherwise, the scattering angles were fixed in the calculation of the corresponding amplitudes while the orientation was varied. At last our calculations were compared with available resultsIn the present work the first and second order scattering amplitudes and the related phase were calculated in the charge transfer channel. The positronium formation, with the impact of molecular hydrogen ion, has been carried out using multiple channel scattering formulation and transition matrix. The calculation of differential cross section has been done by varying the scattering angle from 0 to 180 in the fixed orientation of the molecule. In the next calculation the scattering angles were fixed while the spatial molecular orientation was varied. At last the calculated differential cross section was compared with available results in the literature. The scattering angle spanned from 0 to 180 degrees in the second order nuclear and electronic terms were calculated while the molecular orientation was assumed to be fixed. Otherwise, the scattering angles were fixed in the calculation of the corresponding amplitudes while the orientation was varied. At last our calculations were compared with available resultshttps://ijpr.iut.ac.ir/article_1161_5a98c5d494bc393552486f07a6289330.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126The focusing effect of electromagnetic waves in two-dimensional photonic crystals with gradually varying lattice constantThe focusing effect of electromagnetic waves in two-dimensional photonic crystals with gradually varying lattice constant401404116210.18869/acadpub.ijpr.15.4.401FAFBakhshi GarmiJBarvestaniJournal Article20191126In this paper we studied the focusing effect of electromagnetic wave in the two-dimensional graded photonic crystal consisting of Silicon rods in the air background with gradually varying lattice constant. The results showed that graded photonic crystal can focus wide beams on a narrow area at frequencies near the lower edge of the band gap, where equal frequency contours are not concave. For calculation of photonic band structure and equal frequency contours, we have used plane wave expansion method and revised plane wave expansion method, respectively. The calculation of the electric and magnetic fields was performed by finite difference time domain method.In this paper we studied the focusing effect of electromagnetic wave in the two-dimensional graded photonic crystal consisting of Silicon rods in the air background with gradually varying lattice constant. The results showed that graded photonic crystal can focus wide beams on a narrow area at frequencies near the lower edge of the band gap, where equal frequency contours are not concave. For calculation of photonic band structure and equal frequency contours, we have used plane wave expansion method and revised plane wave expansion method, respectively. The calculation of the electric and magnetic fields was performed by finite difference time domain method.https://ijpr.iut.ac.ir/article_1162_df6b10532384cd39707d7a963fd20fc0.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126Study of charged particle acceleration by magnetic reconnection in a plasmaStudy of charged particle acceleration by magnetic reconnection in a plasma405413116310.18869/acadpub.ijpr.15.4.405FAMMehdizadeMHosseinpourM AMohammadiJournal Article20191126Magnetic reconnection, which occurs in high conducting plasmas, changes the topology of magnetic field lines and converts magnetic energy into the kinetic and thermal energy of plasma and also accelerates charged particles. This phenomenon plays an important role in changing the dynamic of laboratory and space plasmas such as fusion tokamaks and sun’s corona. The electric and magnetic fields generated by magnetic reconnection result in acceleration and drift motion of charged particles. Therefore, charged particles, depending on their injection position and initial kinetic energy, can be accelerated and escape or can be trapped in magnetic fields. In this study by considering different injection positions and initial kinetic energies, we investigate how a particle (proton) is accelerated or trapped. Our numerical analyses show that the spine structure for three-dimensional magnetic reconnection can be considered as a potential mechanism for particle acceleration. In this model, a proton can be accelerated up to a few MeV within a few milliseconds. The particle’s trajectory and final kinetic energy strongly depend on its injection position.Magnetic reconnection, which occurs in high conducting plasmas, changes the topology of magnetic field lines and converts magnetic energy into the kinetic and thermal energy of plasma and also accelerates charged particles. This phenomenon plays an important role in changing the dynamic of laboratory and space plasmas such as fusion tokamaks and sun’s corona. The electric and magnetic fields generated by magnetic reconnection result in acceleration and drift motion of charged particles. Therefore, charged particles, depending on their injection position and initial kinetic energy, can be accelerated and escape or can be trapped in magnetic fields. In this study by considering different injection positions and initial kinetic energies, we investigate how a particle (proton) is accelerated or trapped. Our numerical analyses show that the spine structure for three-dimensional magnetic reconnection can be considered as a potential mechanism for particle acceleration. In this model, a proton can be accelerated up to a few MeV within a few milliseconds. The particle’s trajectory and final kinetic energy strongly depend on its injection position.https://ijpr.iut.ac.ir/article_1163_17bc8948cffa8e4f1d136632073ed453.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126Quantum properties of two-mode entangled coherent statesQuantum properties of two-mode entangled coherent states415420116410.18869/acadpub.ijpr.15.4.415FANGhafourian Momen RazaviAAhanjMSarbisheiJournal Article20191126Coherent states are the quantum states, which give the closest description to classical states. Since their superpositions show quantum properties, research on these states has been of great interest. In addition, having nonclassical properties is necessary for quantum correlations. In this paper, we focus on two-mode entangled coherent states which are out of phase, and study the nonclassical properties such as squeezing of quadrature operators, antibunching and oscillatory photon statistics. Then we discuss about their entanglement, which is a quantum correlation in different conditions and compare the results.Coherent states are the quantum states, which give the closest description to classical states. Since their superpositions show quantum properties, research on these states has been of great interest. In addition, having nonclassical properties is necessary for quantum correlations. In this paper, we focus on two-mode entangled coherent states which are out of phase, and study the nonclassical properties such as squeezing of quadrature operators, antibunching and oscillatory photon statistics. Then we discuss about their entanglement, which is a quantum correlation in different conditions and compare the results.https://ijpr.iut.ac.ir/article_1164_1d673f590a339cf3ae0b4aa1c2c3c688.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126The effect of electron and gamma irradiation on the quality of surface and reflection of silver mirror coated by TiO2 and Ta2O5The effect of electron and gamma irradiation on the quality of surface and reflection of silver mirror coated by TiO2 and Ta2O5421427116510.18869/acadpub.ijpr.15.4.421FAEKhalouieBMirzaIJabbariBMirzaHZabolianJournal Article20191126In this study, the effects of gamma and electron radiation on reflectivity of silver mirrors coated by TiO2 and Ta2O5, in the wavelength range 250 to 1100 (nm) has been investigated. The coatings are considered for space applications in LEO orbit at 500 (km) from the earth surface for three-year mission in space. Electron and gamma dose absorbed within the three-year are respectively about 7.5 (KGy) and 0.4 (KGy) in this orbit. To measure the resistance of TiO2, gamma radiation with CO60 irradiation source was applied on the sample in the range from 0.2 to 20 (KGy) including dose 400 (Gy) at the desired height. At the highest dose, 20 (KGy), radiation effects on both samples were compared with each other. The atomic force microscopy was used to investigate the effect of radiation on the quality of samples surface after radiation, and an spectrophotometer was used to measure the samples reflection before and after radiation. The results showed that in spite of very minor surface changes, and color change of the mirror substrate, its reflection remains unchanged with TiO2 and Ta2O5 coatings.In this study, the effects of gamma and electron radiation on reflectivity of silver mirrors coated by TiO2 and Ta2O5, in the wavelength range 250 to 1100 (nm) has been investigated. The coatings are considered for space applications in LEO orbit at 500 (km) from the earth surface for three-year mission in space. Electron and gamma dose absorbed within the three-year are respectively about 7.5 (KGy) and 0.4 (KGy) in this orbit. To measure the resistance of TiO2, gamma radiation with CO60 irradiation source was applied on the sample in the range from 0.2 to 20 (KGy) including dose 400 (Gy) at the desired height. At the highest dose, 20 (KGy), radiation effects on both samples were compared with each other. The atomic force microscopy was used to investigate the effect of radiation on the quality of samples surface after radiation, and an spectrophotometer was used to measure the samples reflection before and after radiation. The results showed that in spite of very minor surface changes, and color change of the mirror substrate, its reflection remains unchanged with TiO2 and Ta2O5 coatings.https://ijpr.iut.ac.ir/article_1165_b5b5546bf836592f009255c75c021fef.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126A survey of conductivity of nanotubes indirectly doped with nitrogen using equations Kramerz-KronigA survey of conductivity of nanotubes indirectly doped with nitrogen using equations Kramerz-Kronig429433116610.18869/acadpub.ijpr.15.4.429FARKeshtmandMKhanlaryZKeshtmandJournal Article20191126Doping of carbon nanotubes with nitrogen should provide more control over the nanocarbon electronic structure. In addition to the chemical and arc-discharge alternative methods used nowadays, we suggest ion irradiationas an alternative way to introduce N impurities into nanotubes. The impinging ions can directly occupy the sp < sup>2 positions in the nanotube atomic network. As an alternative way N nitrogen atoms are introduced due to the same atomic radius. In this work we studied the defects caused by exposure to N2 with various energies with the Raman spectroscopy. Kramers–Kronig analysisis determined the optical conductivityof multiwall carbon nanotudes. Electrical measurements showed that conductivity of samples increases with enhancement of irradiation of MWCNTs, clearly due to creation of more defects and N-C and irradiation-mediated doping of nanotubes is a promising way to control the nanotubes electronic structure.Doping of carbon nanotubes with nitrogen should provide more control over the nanocarbon electronic structure. In addition to the chemical and arc-discharge alternative methods used nowadays, we suggest ion irradiationas an alternative way to introduce N impurities into nanotubes. The impinging ions can directly occupy the sp < sup>2 positions in the nanotube atomic network. As an alternative way N nitrogen atoms are introduced due to the same atomic radius. In this work we studied the defects caused by exposure to N2 with various energies with the Raman spectroscopy. Kramers–Kronig analysisis determined the optical conductivityof multiwall carbon nanotudes. Electrical measurements showed that conductivity of samples increases with enhancement of irradiation of MWCNTs, clearly due to creation of more defects and N-C and irradiation-mediated doping of nanotubes is a promising way to control the nanotubes electronic structure.https://ijpr.iut.ac.ir/article_1166_221aef89611db3cf4871af6f1cf7c807.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126The effect of oxygen flow rate on refractive index of aluminum oxide film deposited by electron beam evaporation techniqueThe effect of oxygen flow rate on refractive index of aluminum oxide film deposited by electron beam evaporation technique435440116710.18869/acadpub.ijpr.15.4.435FARShakouriHHaydariJournal Article20191126The effects of oxygen flow rate on refractive index of aluminum oxide film have been investigated. The Al2O3 films are deposited by electron beam on glass substrate at different oxygen flow rates. The substrate was heated to reach and the temperature was constant during the thin film growth. The transmittance spectrum of samples was recorded in the wavelength 400-800 nm. Then, using the maxima and minima of transmittance the refractive index and the extinction coefficient of samples were determined. It has been found that if we reduce the oxygen flow, while the evaporation rate is kept constant, the refractive index of Al2O3 films increases. On the other hand, reduced oxygen pressure causes the Al2O3 films to have some absorption.The effects of oxygen flow rate on refractive index of aluminum oxide film have been investigated. The Al2O3 films are deposited by electron beam on glass substrate at different oxygen flow rates. The substrate was heated to reach and the temperature was constant during the thin film growth. The transmittance spectrum of samples was recorded in the wavelength 400-800 nm. Then, using the maxima and minima of transmittance the refractive index and the extinction coefficient of samples were determined. It has been found that if we reduce the oxygen flow, while the evaporation rate is kept constant, the refractive index of Al2O3 films increases. On the other hand, reduced oxygen pressure causes the Al2O3 films to have some absorption.https://ijpr.iut.ac.ir/article_1167_2dbbca132e81ebfd546e99afe9d4d354.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126Ultra-sensitive surface plasmon resonance fiber optic sensors based on gold nanoparticlesUltra-sensitive surface plasmon resonance fiber optic sensors based on gold nanoparticles441446116810.18869/acadpub.ijpr.15.4.441FAMHoseinianMHoseinianSKhoshnevisFKashanianJournal Article20191126Plasmonic properties of metals such as gold is the main factor in the development of optical fiber sensors. Plasmonic property is created by exciting the surface plasmon polaritons by laser radiation. These properties are usually used in boosting and detection. The article examines and compares the collected information such as the length of the fiber optical sensor and the sensitivity of sensors including wave guides, fiber brag gratings and Wagon Wheel optical fiber in recent years.Plasmonic properties of metals such as gold is the main factor in the development of optical fiber sensors. Plasmonic property is created by exciting the surface plasmon polaritons by laser radiation. These properties are usually used in boosting and detection. The article examines and compares the collected information such as the length of the fiber optical sensor and the sensitivity of sensors including wave guides, fiber brag gratings and Wagon Wheel optical fiber in recent years.https://ijpr.iut.ac.ir/article_1168_723a78af91f4b1c2eb9fc285b90ffddb.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695715420191126Suppression of zero order diffraction from the reconstructed images in digital holographySuppression of zero order diffraction from the reconstructed images in digital holography447452116910.18869/acadpub.ijpr.15.4.447FAM RRashidian VaziriNPartovi ShabestariIAlidokhtBZarefarsaniJournal Article20191126The numerically reconstructed images in digital holography contain two undesirable features. After reconstruction, the zero order diffraction as well as the complex conjugate image will be present in pictures and drastically reduce their qualities. Practical applications of digital holography in the context of characterization and measuring the physical properties of objects require the suppression of these two features, before starting the reconstruction phase. In this work, using the required mathematical functions for suppressing the zero order diffraction and by transforming them to their discrete form, numerical filters for passing over the CCD images have been constructed. After passing these filters over the experimentally recorded CCD images, the reconstruction phase has been completed applying the discrete Fresnel transform. Carefully investigating the quality of various reconstructed images, we came to the conclusion that if a filter covers a smaller neighborhood of the recorded CCD images, it will have a better performance in suppressing the zero order diffraction. Among the used filters in this work, a 3×3 average filter showed the best performance in suppressing the zero order diffraction from the reconstructed images.The numerically reconstructed images in digital holography contain two undesirable features. After reconstruction, the zero order diffraction as well as the complex conjugate image will be present in pictures and drastically reduce their qualities. Practical applications of digital holography in the context of characterization and measuring the physical properties of objects require the suppression of these two features, before starting the reconstruction phase. In this work, using the required mathematical functions for suppressing the zero order diffraction and by transforming them to their discrete form, numerical filters for passing over the CCD images have been constructed. After passing these filters over the experimentally recorded CCD images, the reconstruction phase has been completed applying the discrete Fresnel transform. Carefully investigating the quality of various reconstructed images, we came to the conclusion that if a filter covers a smaller neighborhood of the recorded CCD images, it will have a better performance in suppressing the zero order diffraction. Among the used filters in this work, a 3×3 average filter showed the best performance in suppressing the zero order diffraction from the reconstructed images.https://ijpr.iut.ac.ir/article_1169_625c9f1d60573bc3811d2ae671ea1dca.pdf