Introduction Use of hadron therapy as an advanced radiotherapy technique is increasing. In this method, secondary particles are produced through primary beam interactions with the beam-transport system and the patient’ s body. In this study, Monte Carlo simulations were employed to determine the dose of produced secondary particles, particularly neutrons during treatment. Materials and Methods In this study, secondary particles, produced by proton and ion beams, were simulated for a cancer treatment plan. In particular, we evaluated the distribution of secondary neutrons, produced by a 400 MeV/u carbon beam on an electronic crate, which was exposed to radiation field under radioactive conditions. The level of major secondary particles, particularly neutrons, irradiating the target, was evaluated, using FLUKA Monte Carlo code. Results The fluences and radiation doses were applied to determine the shielding efficiency of devices and the probability of radiation damage to nearby electronic systems. According to the results, by using maximum-energy carbon ions (400 MeV/u), electronic devices are exposed to a dose rate of 0. 05 μ Sv/s and an integrated dose of about 34 mSv, each year. Conclusion The simulation results could provide significant information about radiation assessment; they could also be a major help for clinical facilities to meet shielding requirements. Moreover, such simulations are essential for determining the radiation level, which is responsible for radiation-induced damages.

In recent years, inertial microfluidics (the use of inertial forces in microchannels) have attracted much attention aiming particle separation. The advantage of this method over other methods of separation and enrichment is its high-throughput performance and inexpensiveness. In the present study, the purpose of enriching the fluid with particles greater than 15 microns in diameter accomplished by designing a rectangular microchannel with an array of contraction-expansion regions in which expansion regions (reservoirs) had the task of trapping larger particles. By using the finite element method and by solving the Navier-Stokes equations, streamlines and vortex shapes are obtained. It was observed that for inlet flow rates in the range of 0. 25 to 0. 5 milliliters per minute, the highest capture efficiency for particles larger than 10 microns in diameter occurred near 0. 35 milliliters per minute. The effect of parameters such as channel height, number of reservoirs and the initial length of the contraction region on the capture efficiency was also measured. Finally, in order to approach the practical applications, the effect of viscosity change due to replacement of blood (Non-Newtonian fluid) instead of water was also investigated, which resulted in the formation of vortices at higher flow rates. In general, vortices created in the expansion region, whose intensity depends on the parameters mentioned above, play a dominant role in particle separation, while inertial lift forces appear as an initial guide.

Purpose: Managers are one of the important elements of an organization, for this reason, in order to draw the future of the organization, it is necessary for the planners to specify the conditions of their selection and appointment. Therefore, the current research has been done with the aim of identifying and analyzing the components of selecting future principals.Method: In this research, comparative and benchmarking method is used as a prospective approach. This approach is based on the belief that today's advanced organizations/countries can be considered as a model for the future of another organization/countries in their respective subjects. For this, first, the fields of comparison and benchmarking were determined using Brody's four-step comparison method; then the countries of Canada, Finland, Australia, South Africa, and Japan were selected according to the qualitative balance value in the international advanced TEAMS test, human development index, life quality index(health, instruction, and welfare), education quality index, and other scientific-scholarly indexes; finally, by extracting the criteria for the selection and appointment of principals through content analysis and comparison with Iran, the proposed framework for Iran has been presented.Findings: A total of 61 components for the selection of secondary school principals were identified from among the studies conducted in the selected countries in this article. By extracting the commonalities and differences of each of the components among the countries, it was found that the highest index of manager selection and appointment belongs to Japan and the lowest one is related to Finland.Conclusion: There are similarities between the components of selection of principals of secondary schools in Iran and selected countries. In Iran, special attention should be paid to important components such as adherence to religious principles, appropriate personality traits, creativity and innovation, motivation to develop capabilities, professional growth, power of supervision and accountability, social image, leader skills, and purposefulness and foresight.

Background: The present study aimed to investigate the equivalent dose in vital organs, including heart and lung, due to secondary particles produced during breast proton therapy. Materials and Methods: The numerical ORNL female-phantom was improved and simulated using the Monte Carlo MCNPX code. The depth-dose profile of proton beams with different energies was simulated. The proper energy range of incident proton beams has been estimated in order to have the Bragg peaks inside the breast tissue. The equivalent dose of secondary particles, including neutron and photon in vital organs, were evaluated. The TALYS code was used to investigate the neutron and photon particles’ production cross-sections. Results: The results showed that for the proton energy range of 60-70 MeV, the Bragg peaks positioned inside the breast. The maximum dose of 0. 65 mSv/nA-p was in Heart-Left Ventricle due to neutrons production by incident 70 MeV protons. However, the maximum absorbed dose, due to the secondary particles, was less than 0. 0004% of proton equivalent dose at the Bragg peak. The maximum photons dose and the protons dose into the Heart-Left Ventricle were 8. 42 μ Sv/nA-p and 68. 08 μ Sv/nA-p, respectively, which were negligible compared to the proton equivalent dose at the Bragg peak. Conclusion: The results confirmed a noticeable lower dose in the heart and lungs for breast proton therapy, compared with the previously reported dose for breast radiotherapy using photon. Most of the dose absorbed by the organs is due to the secondary neutrons, but those are low enough to be neglected.

Sedimentation tanks are designed for removal of floating solids in water flowing through the water treatment plants. These tanks are one of the most important parts of water treatment plants and their performance directly affects the functionality of these systems. Flow pattern has an important role in the design and performance improvement of sedimentation tanks. In this work, an experimental study of particle-laden flow in a rectangular sedimentation tank has been performed. Kaolin was used as solid particles in these experiments. Also, a numerical simulation was developed using the finite volume method with a k-e turbulent model. The results of the numerical model agree well with the experimental data. Hydrodynamic parameters and flow patterns of the fresh water flow and particle-laden flow are also compared in this study. The results show that the existence of particles completely changes the flow structures. It seems that the main reason for this phenomenon is the particles settling. Our experimental observations and numerical results show that parameters such as the maximum stream wise velocity, fully developed location, shear stress coefficient at the bottom of the tank and so on are different in water-containing particles compared to pure water and the inlet concentration strongly intensifies the differences.

Radiotherapy using various beams is one of the methods for treating cancer, Hadrons used to treat cancers that are near critical organs. The most important part of the cell that is damage by ionizing radiation is DNA. In this study, damages induced in the genetic material of living cells (DNA) defined by the atomic model from the protein data bank (PDB) have been studied by radiation of monoenergetic protons and its secondary particles using Geant4 code. The total SSB yield is independent of energy of incident particle. The total DSB yield is increase with increasing of incident particle LET. The ratio of total inelastic events to absorbed dose for primary protons as well as its secondary particles is independent of energy. The contribution of secondary particles in the formation of single-strand breaks and double-strand breaks have been calculated. The DSB yield generated by secondary particles is increase with decreasing the energy of the incident particle and the contribution of secondary particles to the generate of double-strand break for energies less than 5 Mev is greater than their contribution to the creation of single-strande breaks. The ratio of double-strand breaks to single-strand breaks have been reduced by increasing the energy of the radiation particle.

Collision of protons with background gas and beamline wall in proton therapy causes the creation of secondary particles, e. g. neutrons, which results in more difficulties in curing the tumors. In the present simulation-based study, the optimum diameter of proton beamline was determined to minimize the production of secondary particles in the presence of electric field with the magnitude of 50 kV/m, perpendicular equal magnetic fields of 0. 7 T, and background gas of argon under Bounce boundary conditions via finite element method. The results showed that the optimum diameter of the beamline for minimization of the secondary particles in the spot scanning proton therapy in the aforementioned conditions was 7 mm. Also, the values of drift velocities of protons were plotted in different time steps of 10 ns to 50 ns for the optimized size of the beamline. Due to few interactions of forwarding particles with background gas, the results showed that the forwarding particles in the propagation direction have greater velocities than those of rear particles. The results can be used in spot scanning proton therapy for curing the localized cancers.

Deviation angles of secondary electrons and muons in simulated extensive air showers were studied. The angles have wide distribution, whose width depends on energy cuts imposed on shower particles. In this work, variation of deviation angles with the energy of secondary particles, shower energy, primary direction, and core distance was investigated. The results put limitations on application of hodoscopic devices in cosmic ray and gamma ray observations.

High-energy heavy ions produced by accelerators are used in industrial and medical applications. Recently carbon ions have been used in the treatment of cancerous tumors. Heavy ions by the spallation process will activate the soft tissue components before tumors. In this research by GEANT4 toolkit and MCNPX code simulation were tried to calculate the secondary particles and radioactive elements produced in the soft tissue around tumors by the carbon ions spallation process. In the MCNPX code, the F8 tally card with the FT8 command was used to extract the activation and spallation information of secondary particles in the Z1=1 to Z2=25 atomic numbers range. It was shown that a wide range of radioactive elements was produced in healthy tissues in carbon therapy. addition to produced secondary particles, the Be-10 and C-14 radioactive elements were produced in high-energy carbon ions in soft tissue. Also, the GEANT4 toolkit result of produced secondary particles dosimetry was shown that the secondary particles dose per carbon ion is between 1.66 to 33.54 nGy for carbon ion energy between 1140 to 5160 MeV. The tail for 3480, 4080, and 5160 MeV of carbon ion energy are 0.12,1.01 and 11 cm respectively. The carbon ion beam divergence increases with beam energy and achieve to 33 mm for 5160 MeV carbon ion.

Introduction: Due to nuclear interactions between the tissues and high-energy protons, the particles, including neutrons, positrons, and photons arise during proton therapy. This study aimed at investigating the dose distribution of proton and secondary particles, such as positrons, neutrons, and photons using the Monte Carlo method. Material and Methods: In this study, a beam of protons was utilized with the energies of 160 and 190 MeV, which are more popular for brain tumor treatment. This beam irradiated the brain phantom after passing through proton therapy nozzle components. This phantom has a tumor with a radius of 3 cm in its centre. The most important parts of the nozzle include magnetic wobbler, scatterer, ridge filter, and collimator. Results: The results show that while using protons with the energy values of 190 and 160 MeV, the equivalent dose fractions in tumor, brain, skull, and skin to the total equivalent dose in the head are 61. 8 (62. 4%), 10. 4(10. 9%), 6. 07(3. 69%), and 21. 7(23%), respectively, regarding the primary and secondary particles. Conclusion: According to the obtained results, in spite of the fact that most of the equivalent dose was inside the tumor volume, the skin of head has received the noticeable dose during proton therapy of brain which needs more concern.