مجله فیزیک کاربردی
سال سیزدهم شماره 2 (پیاپی 33، تابستان 1402)

Gene is a factor encoding genetic information and the basic unit of inheritance. Gene expression is a phenomenon consisting of two complex stages of transcription and translation. In this study, the yeast cell of Saccharomyces cerevisiae evolution is investigated due to the importance of the gene expression phenomenon. To clarify the accuracy of the obtained results, we have used experimental data on the Saccharomyces cerevisiae yeast cell from the gene bank. We are using chaos theory to study gene expression due to the nonlinear dynamics of the phenomenon. The obtained results predict that, by increasing the rate of degradation in the messenger arena to 0.03, we have reached the threshold value for the gene expression phenomenon. Also, we have recognized that increased transcription is associated with an increased mRNA degradation rate. The optimal values of transcription delay rate (18.2 min) and protein degradation rate (0.03) were obtained. There was a good agreement between the experimental and theoretical results.

The penning trap, invented in 1959 by H. Dehmelt, is a combination of an inner electric dipole field and a constant magnetic field. A charged particle trapped in the Penning trap is called a geonium atom. The energy levels of the geonium atom are known in the non-relativistic limit, using the solutions of the Schrodinger equation, and for the case when the gravitational field of the Earth is negligible. In this article we write the Dirac equation for the geonium atom, coupled to the weak gravitational field of the Earth, and study its energy levels using perturbation techniques. If the Newtonian gravitational potential is , the dimensionless perturbing parameter is  , where c is the velocity of light. It is found that the effect of these perturbations affects the energy levels by a factor of almost . This tiny shift in the energy levels may be used to investigate the effect of the gravitational field on earth.

The electronic and transport properties of the zigzag and armchair borophene nanoribbons β12 with different edge geometries using the multi-band tight-binding model and Landauer Butticker formalism were investigated by the mode matching model. Our results show that nanoribbons with different edge geometries show different electronic behaviors from metal phase to semiconductor according to and under thermal gradient or voltage poetical produce electrical current from nano ampere to microampere (most of them have ohmic behavior). Also, vacancy defects with controlling energy gaps could change the phase from metal to semiconductor or from semiconductor to metal in different edge geometries. Moreover, vacancy defects could control the values of electrical currents. Finally, the edge geometries; and defect engineering with application thermal gradient or electrostatic potential could control the electronic and transport properties and convert borophene nanoribbons into a good candidate for application in nano-electronic devices.

This study investigates the effect of the filter on the visibility of fringes in single-photon interference. A pair of photons by spontaneous parametric down-conversion is produced using a nonlinear crystal. One of them passes through a Mach-Zehnder interferometer due to the principle of indistinguishability of the paths, which interferes with itself. By changing the length of the paths of the Mach-Zehnder arms with the help of a stage, the interference happens in the coincidence pattern. In order to align the optical elements and minimize the optical path difference in the interferometer arms, interferometry with laser and white light has been used before single photon interferometry. By placing filters with different bandwidths in the signal and idler photons path, we see interference fringes with different visibility. An interference pattern is obtained by recording the coincidence between the correlated photons. The results show that the frequency bandwidth of filters affects the coherence length of generated photons and so the visibility of interference fringes.

In this research, first the bismuth ferrite nanostructure doped with Cu = 0.20 was prepared and then, its (Bi1-xYxFe0.80Cu0.20O3) doping with Y = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30 by a sol-gel method at a temperature of 650 ºC and a 1 h were studied.  The structural properties of the samples have been characterized using XRD, FESEM, FT-IR, and EDX. Investigations of the structural properties showed that by increasing the Y percentage, the peaks are broader and partly have disappeared due to their small size. The magnetic and dielectric properties of the samples using the analyses of VSM, and LCR meters have been investigated. Investigations of the magnetic properties showed that by increasing Y content, the sample's ferromagnetic properties gradually increased. So that the saturation magnetism of our work (2.5 emu/g) compared to the work of others (0.85 emu/g) significantly has increased. Also, the substitute of bismuth ferrite with yttrium and copper has led to the change of the site of Fe in the octahedral center of FeO6 and the change of the bond angle in O-Fe-O. It has created an asymmetry in the structure, which has improved the dielectric properties of the samples. The results of the dielectric properties showed that the dielectric constant, dielectric loss and electric conductivity in the samples doped with Y and Cu are more than in samples without doping.

This paper investigates the effects of cold plasma radiation on the percentage, velocity, average germination per day, germination index, and prose and growth of green cumin roots. A factorial experiment was performed in a randomized design in 5 repetitions. Test factors included pretreatment of cold plasma irradiation time at 0, 3, 6, 9, and 12 minutes by 7 and 14 kV and 800 Hz plasma generators. The results of this work showed that the treatment time and the applied voltage of cold plasma significantly affect the percentage, velocity, average of germination per a day, germination index, and prose and root of the green cumin seed. Among all treatments, a dose of treatment with time of 6 minutes at a peak voltage of 14 kV had the greatest effect on the referred characteristics, except increasing root in which plasma treatment with a dose of 3 minutes has the most effect. Cold plasma has been generated with a dielectric barrier discharge (DBD) is a hand-made and designed in on desk dimensions, in which air is used as plasma active gas.