مجله علوم و فنون هسته ای
سال چهل و یکم شماره 1 (پیاپی 91، بهار 1399)

Pulse oximetry is a very significant method in  medical monitoring . Due to the restriction in the use of the transmission pulse oximeter in high-density tissues, this research aims to focus on the study and development of the reflectance pulse oximeters, because it is able to show the blood oxygen saturation level (2SaO) in various densities. To this end, considering the benefits of photon diffusion theory over Beer-Lambert law, a new mathematical (analytical) method was developed to investigate the inensity reflective light propagation in a heterogeneous medium such as a fingerprint. Then, using the obtained analytical model, source-detector space was optimized so that by decreasing the sensitivity of the motion effects on light scattering the accuracy rate will increase. To verify the results obtained from the analytical model, Monte Carlo simulation results were used as a standard method compared to experimental data. This comparison showed the agreement of the analytical model with the results of these two methods with minor differences. By using the sensitivity function, the optimum distance of the detector from the light sourcewas obtained 4.8 mm and 2.8 mm for red and infrared lights, respectively. An overview of the results suggests that light propagation characteristics can be accurately assessed through an analytical model.

In the present research, the vanadium recovery mechanisms from Saghand –e- Yazd magnetite ore by sodium carbonate was studied as oxidant and acid leaching technology, and also the effect of the different parameters on the kinetics of the vanadium dissolution was investigated. The results showed that the temperature of roasting, the time of roasting  , sodium carbonate as the factor of roasting, as well as the temperature of leaching, time of leaching, size of ore particles, sulfuric acid concentration, and liquid to solid ratio are very important factors in the efficiency of vanadium extraction from ore. Optimum parameters in roasting process were considered temperature: 1000 °C, roasting  time: 2 h, sodium carbonate: 40 wt% (additive roasting), also leaching temperature: 85 °C, leaching time: 4 h, particle size: smaller than 100 microns the concentration of sulfuric acid: 4 M and liquid to the solid ratio: 10/1 mL/g were obtained in the leaching process. According to the kinetic study of the vanadium leaching based on SCM model, it was concluded that the control effect of the leaching process is intra-particle penetration. Therefore, the vanadium leaching process follows the 1-2/3X-(1-X)2.3</sup> kinetic model. Also, the activation energy of the process was 2.19 kcal per mole, which corresponds to the reported theoretical values for the state in which the intra-particle penetration controls the process.

Promethium is one of the rare earth elements of Lanthanides. This element is no found on the earth’s crust. All  its isotopes are radioactive. The isotope 147</sup>Pm is a pure beta emitter and very useful in industry because of its radioactive specifications. To name its applications one can point to usage as beta source in nuclear gauges, self-luminary lamps and nuclear batteries. This radioisotope produces via two methods, one from extraction of fission products waste and the second from thermal neutron irradiation of 146</sup>Nd. In this research, natural neodymium was irradiated in Tehran Research Reactor (TRR) and the gamma and beta spectrums were obtained. In addition, theoretical calculations were done. In this way, acceptable consistency in the results was obtained and the activity and radioactivity of the products were compared.

In this paper, the potential energy surfaces of nuclei with atomic numbers Z=90-100 within the microscopic-macroscopic Cranked Nilsson-Strutinsky (CNS) formalism are studied, and the axial quadrupole deformation parameter for these isotopes has been calculated. Our calculations showed that the nuclei in this mass region have an average deformation about ε2=0.2 in the ground state and an average deformation about ε2=0.6 in the isomeric state. With increasing the neutron number or proton number, the axial quadrupole deformation increases slightly, and the potential minima appear at a relatively larger deformation. Therefore, in the studied mass region, the nucleus will be more elongated with increasing the mass number. Also the effect of change of spin on the fission barrier height is studied. The results obtained from the CNS model was compared with the experimental results and also the results of other theoretical models. This comparison showed that the CNS models, as well as the HFBCS model have the better accuracy in comparison with the other models, and so these are the proper models to produce the quadrupole deformation parameters of heavy and superheavy nuclei.

The loss of coolant accident is due to the reduction of the coolant fluid volume in the first circuit. The direct cause of this accident is the mechanical failure or fatigue in the material of the first circuit components during the power plant operation. This accident, which is a design-based accident, is an important factor in assessing a nuclear power plant safety. If the break occurs in the main circuit of the first circuit with a diameter greater than 25% of the cross-section area, it shall be referred to as a large break. In this paper, this accident with a break diameter of 850 mm is modeled and analyzed using the TRACE code in a VVER-1000 reactor. The TRACE code is specifically designed for coolant loss accidents. With the help of this analysis, it is possible to have an accurate estimate of the reactor's safety and to obtain significant economic considerations instead of conservative assumptions assessment. Finally, the results of the TRACE code have been compared with the final safety analysis report of the power plant as well as previous research by the RELAP5. The results indicate the accuracy of the TRACE code in modeling the large break accident.

This study investigates the direct effect of fast neutrons with the energy ranging from 2MeV to 14MeV, and calculates the single-strand break and double-strand break on the Deoxyribon Nucleic Acid (DNA) atomic structure, using Monte Carlo method. To this end, Geant4 toolkit and its low energy extension, known as Geant4-DNA, were used. The DNA atomic structure extracted from the Protein data bank and water was selected as a substance for the biological matter. The step length in low energy extension works is in the range of nanometer and less. On the other hand, the average free paths of neutrons in the energy rang from 2MeV to 14MeV was obtained in the unit of centimeters. Under these circumstances, running the program using a computing system will also be lengthy. As a result, the spectrum of secondary particles from neutron interactions with the atoms of water molecules was targeted. The Evaluated Nuclear Data File (ENDF) and the theoretical calculation were used to extract secondary particle spectra. This method reduces the execution time to more than about one-tenth. Then, the relative biological effectiveness (RBE) of the neutrons were also simulated using 60Co γ-rays as the reference quality. The model succeeded in reproducing the general behavior of RBE as a function of neutron energy, which agrees well with the data reported in the literature.

In this paper, the effect of the initial electron energy with E0=1-10 MeV, its distribution function and pre-plasma background temperature T=0.5-10 keV on the optimum transport into the dense fuel with the density ρc=292-828 g.cm-3 have been investigated analytically for fast-shock ignition concept. The analytical results showed that for Te ≥ 5 keV, the Coulomb logarithm of the charged particle is weakly dependent on the pre-plasma temperature, and it seems that the plasma stopping power is approximately independent of background temperature. Therefore, it could be concluded that pre-plasma temperature is not a key parameter for the electron penetration improvement, and the electron penetration can be optimized by a decrement of fuel density and increment of electron incident energy; in a way that the optimal condition obtained about E0≈4.5 MeV for electron incident energy and ρc=300 g.cm-3 for pre-plasma density. Furthermore, investigating the impact of the fast ignitor wavelength and electron energy distribution function showed that the electron distribution function is almost independent of the background temperature and by considering quasi two-temperature distribution function for electron and fast ignitor wavelength λif ≈ 0.35 µm, the optimized penetration may be obtained. The analytical results showed an acceptable agreement with those of Monte Carlo simulations.

One of the most common laser proton acceleration mechanism is Target Normal Sheath Acceleration (TNSA) method. The use of a foam layer in front of the main target plays an important role in the amount of laser energy absorption by the electrons and consequently the acceleration of the proton. The front layer can be either uniform and homogeneous or nano-structured. In this study, by assuming a nanostructured foam layer, and using two-dimensional particle simulations code, the effect of nanoparticle’s radius on the proton cut-off energy is investigated. Particles with radii of 10, 60 and 120 nm and random sizes in the range of 10 to 120 nm have been studied and simulated in a front layer with thickness of 10 and 20 μm with near-critical average density at laser intensity (I≈1020W/cm2). According to the results, in the case of thin foam layer, the differences of electron and consequently proton spectra are negligible. However, by increasing the foam thickness, the influence of nanoparticle radius causes a further dissociation in the final proton energy spectra. So that, the proton energy increases almost 45% by reducing the nanoparticle size from 120 nm to 10 nm.

For specific clinical diagnoses, positron emission tomography (PET) can detect more sites of disease than conventional anatomical imaging such as x-ray computed tomography (CT) or magnetic resonance imaging (MRI). Interpretation of PET can be difficult; however, PET images have few anatomical landmarks for determining the location of abnormal findings. Combining PET and CT images acquired sequentially on their separate devices provides a partial solution to this problem. In earlier years PET/CT has an important role in detecting tumors, planning radiation treatment and evaluating response to therapy. Differences in PET and CT imaging time, especially in the lung region, cause artifacts and errors in estimating tumor uptake and volume determination. The purpose of this paper was to investigate qualitative and quantitative errors due to respiratory artifacts on tumors of the lung. For this purpose, the XCAT phantom was used to simulate respiratory motion and also, STIR was used to apply attenuation maps on reconstruction of PET images. The evaluation of results was performed by ROI and SULmax parameters. The images from various methods of attenuation correction, indicated that respiratory motion on regions above the lungs is poorly. The best method is the Initial review of PET images to obtain the size and location of the tumor and then make a decision about the appropriate respiratory phase based on the size and location of the tumor for attenuation correction of PET images.

Nuclear Regulatory Body is a state-run institution which is created by act of parliaments. The main responsibility of this body is to formulate, approve and enforce regulations and rules regarding safety, security and safeguarding nuclear activities within the framework of the main and upstream laws, and to monitor the implementation of these regulations and rules. Nowadays, the establishment of safety and security in nuclear activities, both in national and international levels is essentially dependent on the existence of such an institution. Although the establishment of a state institution lies under the sovereign jurisdiction of states, in terms of significance and sensitivity of nuclear regulatory bodies in regulating of nuclear activities, in both national and international levels, the international community and International Atomic Energy Agency have provided certain requirements concerning the necessity of creation and effective independence of these regulatory bodies, which states logically and legally have to comply with them. After explaining the concept of this organization, the present article examines and evaluates the legal bases of the mentioned requirements and the degree of alignment of the current structure of the country's regulations and nuclear supervision with those requirements

In the present research, composite adsorbents consisting of nano clinoptilolite and polyacrylonitrile (PAN) were prepared. The synthesized composites were characterized by XRD, XRF, FT-IR, DTG and SEM analysis techniques, and finally the adsorption behavior of the composites toward zirconium was investigated. In this nano adsorbent, nano-zeolite clinoptilolite acts as an active component for the absorption of zirconium ions, and polyacrylonitrile plays a bining role. In addition, by changing the size of zeolite particles from micrometer to nanoscale, the adsorption capacity and the kinetic of the adsorption process was increased significantly. The absorption rate by nanocomposites was very rapid and more than 75% of the maximum absorption capacity for zirconium was obtained in the first 5 hours. The SEM image showed that zeolite particles are bonded to each other by a PAN polymer. The porous structure of the nanocomposite allowed permeation of the ions from solution into nanocomposite beads and reaching the ion exchange sites. The effect of pH, initial ion concentration, contact time, and temperature were examined. The optimum contact time and pH were 24 h and 2, respectively. The maximum adsorption capacity of the composite was 18.65 mg.g-1 and the composite was able to remove 80% of Zr+4 from 0.01 meq.mL-1 aqueous solutions. The kinetic and thermodynamic parameters were extracted. The experimental data were well fitted with a pseud-second order kinetic model with good correlation coefficients. In addition, the theoretical values obtained from the equation showed a good agreement with experimental values. Therefore, the pseudo-second order kinetic equation can be considered as a suitable model for interpreting experimental data. The agreement of the experimental data with the Pseudo-second order kinetic model showed that overall rate constant controlled by chemical sorption. In addition, the constant rate of absorption by nanocomposites was higher than that of a clinoptilolite-polyacrylonitrile-macrometric composite. In other words, the absorption of zirconium ion on nanocomposite was significantly higher than that of a zeolite composite with macro dimensions. Positive ΔH° and negative ΔG° were indicative of the endothermic and spontaneous nature of process. The equilibrium data were analyzed by the Langmuir, Freundlich, and Dubinin–Radushkviech isotherm models. D-R isotherm model indicated that ions were uptake through an ion exchange process. The obtained RL values range between 0 to 1, indicating Zr adsorption was favorable. Comparison of Q0 values for adsorbents showed that the nanocomposite has the highest absorption capacity for zirconium ion. This high Q0 value can be explained by the nanoscale size of the composite.

Monte Carlo method is widely used for simulation of industrial and medical radiography due to its powerful ability to simulate statistical phenomena such as radiation generation and transport, and detection processes. Digital radiography is practically applied in two branches of computational radiography (CR) and direct radiography (DR). In this study, computational radiography simulation using the FLUKA Monte Carlo code was developed to provide a framework for studying image contrast as one of the most important parameters of image quality. To investigate the contrast a standard aluminum sensitivity component made of ASTM 1647 standard was used. The simulation of this gauge, along with a complete simulation of the X-ray generator and imaging plate, has been done to assess the image contrast, and and a method has been presented to examine the image contrast. In order to validate the proposed method, practical experiments have been carried out on the contrast sensitivity standard gauge. The simulation results obtained through the proposed method are in good agreement with the results of practical experiments.

Using coherent light sources for manufacturing optical dosimeters is of considerable interest. Optical dosimeters are mostly employed for radiotherapy applications; where knowing the temperature dependency of refractive index of the used material in the core of dosimeter, often water, is required. In this work, by setting up and employing an interferometer in the laboratory, the temperature dependency of refractive index of water is measured. The setup is fully described and the required theoretical relations for interpreting the experimental data are developed. Comparing the results with the previous experimental data provided by other groups, demonstrats good compromise and confirms the accuracy of the measurements. It is shown that the second-order polynomial model can be efficiently used for interpreting the measurement data. The results of this study can be used in all those applications where knowing the temperature dependency of refractive index of water is a prerequisite.

The present research deals with the investigation of systematic power scaling of Nd:YAG laser systems by preserving the beam quality and misalignment sensitivity. Firstly, by using the distributed refractive power model and the GLAD software, a single dynamically stabilized rod was proposed. The proposed resonator, in comparison with its flat symmetric counterpart, showed a higher fundamental mode volume (at least twelve times) and exhibited the same amount of misalignment sensitivity. Then, due to the limitation of increasing the pumping power in the process of power scaling, the periodic multi-rod resonators, were used based on a basic dynamic stable resonator. Effectiveness of periodic resonators in fundamental mode power scaling have been investigated because of increment of the fundamental mode volume. The results of the investigation have been validated via a two-rod periodic laser resonator. The results can be useful for power scaling of single transverse mode Nd:YAG lasers, without degrading the beam quality and generating more misalignment sensitivity.

In this study, manganese ferrite nanoparticles (MnFe2O4) coated with chitosan (Ch-MnFe2O4) was investigated at different temperatures. We reported the study of synthesis, and characteristics of this superparamagnetic agent, which were well prepared in nano-size via the chemical co-precipitation method. The Ch-MnFe2O4 NPs were annealed at the temperatures of 300, 400 and 500˚C. The structure, morphology, and magnetic properties of the samples were characterized by the X-ray powder diffraction (XRD) and vibrating sample magnetometer (VSM), respectively. The results are indicating that the Ch-MnFe2O4 NPs are biocompatible, and have a cubic spinel crystal structure. The average sizes of the FA-Ch-MnFe2O4 NPs were found to be dependent on the applied temperature. Also, their sizes as well as the magnetization property will extend as the temperature is increased up to 400˚C. By further increasing the temperature, however, they tend to decrease. These NPs have exhibited uperparamagnetic behavior most likely at the 400˚C temperature. Furthermore, the VSM results have been demonstrated that the number of the magnetic momentums will increase by growing the size, so that they are used as contrast agents and able to affect the relaxation time through the dipole-dipole interaction, which is useful in MRI.

Effects of 0, 15, 30 and 60 g per kg of sewage sludge exposed to gamma irradiation at doses of 0, 5, 10 and 20 kGy were investigated on macronutrients and sodium uptakes in the basil root and shoot. The results showed that using 15 and 30 g sewage sludge per kg soil increases the uptake of phosphorus, potassium, calcium, magnesium, and sodium in the root and shoot, as well as the nitrogen of the shoot. The application of 60 g irradiated and non-irradiated sewage sludge with the irradiation doses used in this study per kg of soil did not cause significant effects on phosphorus, potassium, magnesium, and sodium absorption in the shoot and root, nitrogen in the shoot, and calcium in the root. However, it significantly decreased the calcium absorption of shoots. The maximum uptake of phosphorus, potassium, calcium and magnesium in the root and shoot and nitrogen in the shoot was obtained in 30 g per kg sewage sludge irradiated with 20 kGy absorbed dose. The maximum uptake of sodium was revealed in 30 g per kg sewage sludge irradiated with 10 kGy absorbed dose. With application of irradiated sewage sludge relative to non-irradiated in each level, the absorption of all studied elements increased in the basil root and shoot.

This experiment was conducted as a factorial experiment in a completely randomized design with three replications, to investigate the effect of Gamma rays on germination of maize (Zea mays</em>) using the Cobalt-60 radiation therapy apparatus. The first factor consisted of 4 maize genotypes (AR64, Dehgan 400, Fajr 260 and 704) and the second factor was gamma-ray dose in eight levels (0, 50, 100, 150, 200, 300, 400 and 500 Gy). In this study, traits such as root length, stem length, coleoptile length, root number, vigor index, mean germination time and germination percentage were evaluated. The results showed that the differences between genotypes for all traits, the difference between gamma-ray levels and the interaction between genotype and gamma-ray doses factor were significant for all traits except for germination percentage. Genotype 704 with the highest mean of 92.5% and genotypes of Dehgan 400 and Fajr 260 had the lowest germination percentage. Regarding the different reaction of the cultivars to gamma-ray doses, the appropriate dose for RA64 is 100-150 Gy, for Dehgan 400 is 150 Gy, for Fajr 260 is 100 Gy and 704 is 50 Gy. However, doses higher than the values indicated for each of the cultivars had a negative effect on maize seed germination characteristics and growth.

One of priming methods to increase seed germination and seedling growth is gamma irradiation. In the present research, effects of various doses of gamma ray on germination and vegetative traits of cereals, legumes and vegetables were investigated. Irradiation was carried out using gamma cell with 60Co source of 7.8×102 Ci, with irradiation velocity of 0.087 g.s-1 in four levels (10, 20, 30 and 40 Gy) in a completely randomized design with 3 replications. The results showed that germination in wheat, corn, chickpea, and tomato seeds had positive reaction to low doses of gamma radiation; However, bean and onion seed germination decreased with increasing germination dose. In mungbean, cucumber, and lettuce seeds, germination percentage increased for higher doses. The response of different seeds to gamma radiation levels is different, and for some seeds such as wheat, corn, mungbean, chickpeas, tomatoes, and cucumbers, priming with gamma irradiation can be used to increase the percentage of germination and seedling growth. In other vegetative traits no increment was observed in beans, onions, and mungbean, compared to control but the seeds of chickpeas, wheat, corn, cucumber, lettuce, and tomato increased compared to control and showed a positive reaction to priming with gamma irradiation.

The Ichthyophthirius multifiliis is one of the most important protozoan pathogens of farmed and wild fish populations. In this study, histopathological effects of gamma-irradiated trophonts of I. multifiliis coated with alginate nanoparticles in rainbow trout gill were evaluated. Therefore, after adaption period the fish with mean weight 30 g were distributed to 4 groups: Two groups were treated with gamma-irradiated trophonts of I. multifiliis and coated with alginate nanoparticles, gamma-irradiated trophonts of I. multifiliis. One group was infected with active trophonts of parasite as positive control. In negative control group, no treatment was used. On day 30, gill tissue from treated, infected and control fish was analyzed for evaluating the histopathological alterations. The results showed that the use of alginate nanoparticles formulated in gamma-irradiated I. multifilis trophonts can significantly decrease severe hyperplasia, sub-epithelial edema, and fusion of the secondary lamellae, focal and multifocal necrosi in gill. Also, gamma-irradiated trophonts of I. multifiliis coated with alginate nanoparticles induced an increase in amount of the gill macrophages in treated fish. Therefore, the alginate nanoparticles can be in leading development of safe and efficient gamma-irraditad trophonts deliver tool in rainbow trout with more useful behavior and fewer side effects on gill tissue.

High reactivity of uranium hexafluride compound is responsible for the impurity production of hydrogen fluoride in the enrichment industry process. The presence of this interference gas will disrupt uranium enrichment process. For this reason, measurement of hydrogen fluoride gas in uranium hexafluoride matrix as one of the important factors in the enrichment industry was carried out by FTIR spectrometry. Using of a new manifold system and a 10 m pathlength reflectance gas cell can lead to perform the analysis of hydrogen fluoride in the easier and more appropriate conditions than the ASTM method. The results obtained from the optimization of the present method are as flow: reduction of utilized UF6 (≈ 80%), elimination of liquid N2 for sample preparation, and simplification of sampling. Among the five standards and international regulations available, the ISO/IEC 17025 standard considerations is used, and verification parameters such as linearity, accuracy, precision, detection limit, quantization limit, and uncertainty of the results for the effect of the existing errors were studied.