Boron and Boron Compounds in Radiation Shielding Materials

Abstract

A risk to the nuclear industry is radiation, specifically neutron radiation. In order to maintain a safe workspace for workers, better shielding is being developed. Current shielding methods are examined and boron is considered a potential material for shielding. All living beings and non-living things on earth are exposed to the daily radiation of natural radiation sources in the air, water, soil, and even in their bodies, as well as artificial radiation sources produced by humans. To be safeguarded from the detrimental influences of radiation, it is important to be careful about three basic issues: time, distance, and shielding. The longer the exposure time to radiation from the radioactive source or the closer one is to the radioactive source, the higher the radiation dose to be received. The radiation emitted by some radionuclides is so intense that you can be exposed to it even though you cannot see it from miles away. It can only be protected from the effects of such intense radioactive materials with strong shielding. Boron, having a large cross-section, is combined with other materials in order to obtain the desired material properties to have shielding that can be applied in different situations.

1. Introduction

Radiation is the emission or transmission of energy in the form of waves, particles, or electromagnetic radiation through space or matter. It can be produced by the sun, radioactive elements, X-ray machines, and nuclear reactions, among other things [1, 2, 3]. There are two types of radiation: ionizing and non-ionizing radiation. Ionizing radiation is powerful enough to knock electrons off atoms, causing damage to living tissue and DNA. Non-ionizing radiation, such as visible light and radio waves, lacks the energy to cause this type of harm. Radiation is used in various fields, including medicine, industry, and research, but excessive exposure can harm human health.

In daily life, we can encounter high-energy radiation such as alpha, beta particle emissions, X-ray or gamma-ray, or neutron particle emissions in any form, for example, in many various industrial products, including nuclear power plants, in the health sector, both in diagnosis and treatment and in the aviation field [4]. Any of these radiations that we are unintentionally exposed to can be life threatening for us. However, the consequences of such exposures depend on various factors, such as the type of radiation and the energy associated with it, the amount of absorbed dose, exposure time, and so on.

The radiation energies of galactic cosmic rays, solar particle events, medical X-rays, gamma rays, electrons, and neutrons can vary dramatically depending on the source and particle energy. Here are some rough energy ranges for each type of radiation: High-energy particles that originate outside of our solar system are known as galactic cosmic rays. They can range in energy from a few MeV to several hundred TeV, with some rare events exceeding 1020 eV. Solar particle events are bursts of high-energy particles that originate from the sun. These particles have energies ranging from a few MeV to several GeV, with the most energetic events reaching tens of GeV. Medical X-rays are a type of electromagnetic radiation that is used in medical imaging. X-rays used in medical imaging can have energies ranging from a few keV (thousand electron volts) to several MeV. Gamma rays are a type of electromagnetic radiation with extremely high energies. They can be generated by a variety of processes, including nuclear reactions and astronomical phenomena. Gamma-ray energies can range from a few keV to several TeV. Electrons are subatomic particles that have a negative charge. Depending on the source, their energies can range from a few keV to several GeV. Neutrons are subatomic particles that have no charge. Their energies can also vary greatly depending on the source and method of production, ranging from a few MeV to several GeV.

Radiation therapy is a common cancer treatment method. Cancer cells are stopped or killed using high-energy radiation. Radiation therapy can also be used to treat some benign tumors as well as certain blood diseases (e.g., Hodgkin lymphoma). Radiation therapy, also known as radiotherapy, is a type of targeted therapy. While radiation only affects cancer cells, it has little effect on normal cells. As a result, radiation therapy is frequently combined with other cancer treatment modalities (e.g., chemotherapy). Bone diseases can be treated with radiation therapy. Bone cancer (such as osteosarcoma), lymphoma, or multiple myeloma may have spread to the bones or formed tumors in the bones. Radiation therapy is used to shrink or destroy bone tumor formations to treat these types of cancer. Regional pain and bone fractures can also be treated with radiation therapy. Bone metastases (spreading cancer from another site to the bones) frequently cause pain and fractures.

Neutrons are neutral (zero-charged) particles that are used in nuclear power plants. They can easily pass through most materials and interact with the target atom’s nucleus. The majority of sources that emit X-rays and rays also emit neutrons. Because neutrons can form a much more intense ion path as they lose energy within body tissues, neutron radiation is hazardous to body tissues. Other radiations, such as rays, protons, and alpha particles, can be produced as a result of interactions with biological matter. Workers in nuclear power plants and aircraft crews are particularly vulnerable to occupational neutron exposure.

As a result, there is a high demand for effective, long-lasting radioprotective equipment in applications dealing with potential health hazards from various types of radiation. In this section, we will look at radiation and the shielding materials made with boron and boron compounds against it.

The use of special materials such as boron-doped nanoparticles, boron-based polymers, and additives in a boric-oxide matrix to protect people and equipment from the harmful effects of ionizing radiation is known as radiation shielding (see Figure 1). Ionizing radiation is made up of high-energy particles or electromagnetic waves that can cause harm to biological tissues and other materials. By absorbing, scattering, or blocking radiation, shielding materials can reduce the amount of radiation that reaches a given area. The radiation shield’s effectiveness is determined by several factors, including the radiation’s energy and type, the thickness and composition of the shielding material, and the distance between the radiation source and the shielding material. The following equation can be used to calculate the amount of radiation passing through a material [4]:

Figure 1.

The boron-doped nanoparticles and boron-based polymers can be effectively used as potential radiation shielding materials in daily life and work-life environments. The use of additives in the boric-oxide matrix is another promising approach for developing glass-based composites for radiation shielding materials.

$$I=I_0{e}^{-\mu x}$$E1

where $I$ is the intensity of the radiation after passing through a material, $I_0$ is the initial intensity of the radiation, $\mu$ is the material’s linear attenuation coefficient, and x is the material’s thickness. The linear attenuation coefficient, which is affected by the energy and type of radiation as well as the material’s composition, represents a material’s ability to attenuate radiation. The greater the linear attenuation coefficient, the better the material attenuates radiation. The amount of radiation passing through a material is also affected by its thickness; the thicker the material, the more the radiation is attenuated. The equation can be used to calculate the thickness of a shielding material required to reduce radiation to a safe level. The material thickness required to reduce the radiation intensity to the desired level can be calculated using the material’s linear attenuation coefficient and the radiation’s initial intensity. Radiation shields are materials that are used to protect people and equipment from ionizing radiation. The radiation shield’s effectiveness is determined by several factors, including the radiation’s energy and type, the thickness and composition of the shielding material, and the distance between the radiation source and the shielding material. Eq. (1) can be used to calculate the intensity of radiation passing through a material and the thickness of shielding material required to reduce the intensity of radiation to a desired level.

2. Gamma, X-ray, and neutron shielding properties of boron and boron compounds

2.1 Gamma, X-ray, and neutron shielding of boron polymers

Nagaraja et al. [5] investigated X-ray and gamma radiation shielding parameters such as mass attenuation coefficient, linear attenuation coefficient, Half Value Layer (HVL), Ten Value Layer (TVL), effective atomic number (Z_eff), and electron density of various boron-based polymers [Polymer A-Polyborazilene (B₃N₃H₄), Polymer B-4-Vinylphenyl Boronic acid (C₈H₉O₂B), Polymer C-Borazine (B₃N₃H₆), Polymer D-3-Acrylamidophenylboronic acid (C₉H₁₀BNO₃) Polymer E-Phenylethenylboronic acid (C₁₄H₁₉BO₂), Polymer F-4-Aminophenylboronic acid (C₁₂H₁₈BNO₂) and Polymer G-3-Aminophenylboronic acid (C₆H₈BNO₂)]. In addition, the neutron shielding properties of boron polymers were examined. These parameters included the coherent neutron scattering length, the incoherent neutron scattering length, the coherent neutron scattering cross section, the total neutron scattering cross section, and the neutron absorption cross section. They analyzed the different boron polymers’ shielding properties and compared them to one another. Based on the findings of the in-depth study, it is clear that the boron polymer phenylethenylboronic acid is an efficient radiation absorber, particularly for X-ray, gamma, and neutron radiation. They concluded that the boron polymer phenylethenylboronic acid is an effective material for shielding X-rays, gamma rays, and neutrons from the environment. They used a NaI(Tl) crystal detector with a detection area of 2.54 × 2.54 cm² that was put on a photomultiplier tube that was enclosed in a lead chamber. Additionally, they made use of an advanced PC-based MCA. A powdered form of the compound was placed within a circular holder made of perspex with a diameter of 1 cm and a standard thickness of 1 cm. The substance was attached straightforwardly to the opening in the lead shield that served as the location of the source. During the course of their research, they discovered that the half-value layer and the tenth-value layer of the boron polymer derived from phenylethenylboronic acid were significantly thinner than those of the other boron polymers that were studied. Boron polymer with phenylethenylboronic acid added makes it less permeable to gamma and X-rays compared to other boron polymers with the same composition. It was demonstrated that the boron polymer derived from phenylethenylboronic acid has a shorter mean free path compared to the other boron polymers that were investigated. Boron polymer with added phenylethenylboronic acid makes it less permeable to gamma and X-rays than other boron polymers with the same composition. Nagaraja et al. [5] were able to show that the boron polymer made from phenylethenylboronic acid had a greater effective atomic number compared to the other boron polymers that were investigated. In addition to this, they found that the effective electron density of the boron polymer that was generated from phenylethenylboronic acid had the greatest value of all of the values that were investigated. They studied a variety of boron polymers and compared their lengths, cross sections, total neutron scattering cross sections, and neutron absorption cross sections for coherent and incoherent neutron scattering parameters. For the phenylethenylboronic acid boron polymer, both the coherent neutron scattering length and the incoherent neutron scattering length were found to be at their shortest possible lengths. Phenomenally small coherent and total neutron scattering cross sections characterize the phenylethenylboronic acid boron polymer. A boron polymer that contains phenylethenylboronic acid has been shown to have a significant neutron absorption cross section. They assessed several different metrics of coherent and incoherent neutron scattering for a variety of boron polymers. These metrics included lengths, cross sections, the total neutron scattering cross section, and the neutron absorption cross section. The researchers concluded that the coherent neutron scattering length and the incoherent neutron scattering length for the phenylethenylboronic acid boron polymer were both at their shortest conceivable lengths. This was determined by finding that both lengths were at their smallest possible lengths. Both the coherent and total neutron scattering cross sections are exceedingly low in the case of the boron polymer made from phenylethenylboronic acid. The neutron absorption cross section is relatively high in the case of the phenylethenylboronic acid boron polymer.

2.2 The effectiveness of gamma irradiation of polystyrene-b-polyethyleneglycol-boron nitride (PS-b-PEG-BN) nanocomposites

Cinan et al. [1] wanted to investigate the effectiveness of gamma irradiation and the shielding characteristics of PbO-doped crosslinked PS-b-PEG block copolymers and polystyrene-b-polyethyleneglycol-boron nitride (PS-b-PEG-BN) nanocomposites materials in their work. In order to investigate the gamma-ray shielding properties, crosslinked PS-b-PEG block copolymers and PS-b-PEG-BN nanocomposites were combined with varying percentages of PbO. The production of the copolymer was carried out using various techniques, including emulsion polymerization [6, 7]. For the purpose of their research, the researchers utilized the crosslinked PS-b-PEG block copolymers as a polymeric matrix. They also utilized BN and PbO as the radiation absorption functional material in order to lessen the impact of high-energy gamma rays. The gamma-ray attenuation coefficients were compiled, and a study was conducted using the Linear Attenuation Coefficients (LACs, μ_L) and Mass Attenuation Coefficients (MACs, μ_m) of the crosslinked PS-b-PEG block copolymers-BN-PbO nanocomposites for a variety of items in the linked photon energy area. They found an admissible consistency between the experimental and theoretical μ_L and μ_m of the samples, and the measured and calculated values reflect variations with the modification of the polymer type used to improve the gamma radiation shielding materials. In addition, they found that the samples had an admissible consistency between the experimental and theoretical μ_ms and μ_Ls. In order to achieve the same goal, HVL, TVL, the Mean Free Path (MFP), and the Radiation Protection Efficiency (RPE) values of crosslinked PS-b-PEG block copolymers-BN-PbO nanocomposites were examined in the important critical photon energy area for the gamma-ray attenuation properties. Their findings are a very crucial indicator of the degree to which the material in question is effective at shielding radiation. At the Physics Department of Karadeniz Technical University, the gamma irradiation attenuation factors of the examined composites were obtained for a wide variety of energy spectrums emitted from a ¹⁵²Eu source using an high-purity germanium (HPGe) detector framework. These energy spectra were measured using gamma rays released from a ¹⁵²Eu source. To acquire experimental outputs throughout the surveying method, they profited from the computer program Gamma Vision, which maintains powerful multi-channel analyzer capabilities. This allowed them to acquire the outputs of the experiments. Figure 2 shows the representation of the HPGe detector for gamma irradiation attenuation experiments.

Figure 2.

Diagram of the HPGe detector for gamma irradiation attenuation experiments.

Mixing PbO in the crosslinked PS-b-PEG block copolymers and the PS-b-PEG-BN nanocomposites matrix increases the odds of contact between the incoming gamma irradiation and the shielding material atoms. It can be determined that their samples can treat as shieldings as opposed to the low dosage fractions from gamma irradiation origins. The LACs values fall together with a surge in gamma radiation energies. The occasion for that circumstance is the interaction of gamma radiation with materials via a photoelectric effect, Compton scattering, and pair creation. The photoelectric effect is especially significant in the low gamma energy regions; hence, μ_L values are higher in the gamma radiation energy zones in which they are found. The Compton effect is predominant in locations with a medium level of irradiation energy, whereas pair creation is predominant in places with an elevated level of gamma irradiation energy; hence, μ_L worthies begin to decrease with the increase of gamma energies. In addition, it was observed that the radiation protection capacities of the samples improved when PbO or BN percentages of the produced materials were modified. The present study reports on the mass attenuation coefficients (MACs) measured at discrete gamma-ray energy intervals ranging from 121.782 keV to 1408.006 keV. The findings reveal a negative correlation between gamma-ray energy and attenuation aptitude, indicating that as the gamma-ray energy increases, the attenuation of all samples gradually decreases. This is the case. The mixing of PbO in the crosslinked PS-b-PEG block copolymers and the PS-b-PEG-BN nanocomposites matrix results in an increase in the possibility of interaction between the incoming gamma radiation and the gamma-ray shielding atoms. This is because it is more difficult to shield photons with high gamma energies than it is with low gamma energies of photons. It is possible to conclude that the samples can act as shields even when exposed to gamma irradiation sources that produce the modest dose rates. When there is an increase in the amount of gamma radiation present, the values of the μ_ms go down. In addition, it was found that the PbO and BN percentages of the manufactured materials had an effect on the radiation protection capacities of the samples and that these percentages had an improvement in the radiation protection capacities of the samples. When they examine all of the samples side by side, they can conclude that the larger μ_ms and optimal absorption of gamma rays are due to the increased percent rates of the PbO element in the various compounds. It may be underlined that the samples generated in the research disclose significant and dependable results to enlighten radiation shielding studies if the μ_m results of all of the samples are examined with a broad viewpoint. This is because these samples were developed in the course of the research. The HVL, TVL, and MFP values that were obtained for these samples are the most important indications of the radiation shielding ability of the newly created materials for radiation shielding at intervals of gamma-ray energy ranging from 121.782 keV to 1408.006 keV. The value of these coefficients determines how significant their radiation protection efficiency is. The lower the value, the more significant their radiation protection efficiency is. The HVL, TVL, and MFP values all scale up or down about a single property. The TVL value, which is the shielding thickness value required to stop 90% of the emitted photons, that is, to absorb them, increases as the photon energy increases. This is because the shielding thickness value is proportional to the value required to stop 90% of the photons. Their findings are an extremely useful indicator of the radiation shielding capacity of the material in question; more specifically, one may conclude that the lower the TVL value of any given sample is, the greater the radiation shielding efficiency will be as a result of the reduced thickness requirements. The HVL values of the samples provide convincing guidance regarding the shielding capacity of the materials in decreasing the photon quantities to half of what they are currently at for the sample thickness. One of the main characteristics that clearly explain the gamma radiation degrading abilities of the shielding substances that are used is the MFP value. The better a substance’s ability to shelter other particles from radiation, the lower the MFP value should be. The results that they obtained show that the MFP rates of the other samples increase as the photon energy increases. The success of the materials that were created to measure the attenuation of the gamma photons in the various energy intervals can be monitored by computing the RPE. Therefore, the RPE values for the PbO doped the crosslinked PS-b-PEG block copolymers and the PbO-doped PS-b-PEG-BN nanocomposite materials have been monitoring the densities of the photons as a function of different gamma-ray energy intervals. In their research, it can be seen that the RPE values tend to decrease with increasing energy for all the evaluated composites. According to these findings, the PbO-doped polymer-based composites that they developed have a good performance in shielding gamma radiation. That is to say, the recent adjustments to the doping ratios are proving to be quite successful in lowering the intensity of gamma photons. In addition, it was found that the PbO and BN percentages of the manufactured materials had an effect on the radiation protection capacities of the samples and that these percentages had an improvement in the radiation protection capacities of the samples. When one looks at the HVL and TVL values of those samples, one can see that the sample with the PS-PEG (1000)-BN-S0 has the best HVL value for 121.782 keV with 1.336 cm, and the sample with the TVL value of 4.439 cm has the best value for 121.782 keV. It can be seen that the PS-PEG (1500)-BN-S0 sample has the best HVL value, which is 7.801 cm, and the best TVL value, which is 25.913 cm. Both of these values come from the energy level 1408.006 keV. When they compare these values with previously indicated values, which are solely polymers in their structure, the contribution of adding BN to the composite is visible. In addition, BN is thought to be a good neutron absorber. Based on this concept, it is simple to conclude that the contribution of BN is significant, given that one expects that the mineral that was added will also be useful for neutron radiation. This conclusion can be reached since one thinks that the mineral will be useful for neutron radiation. As a consequence of this, the materials from their investigation show that PbO doping occurred in the crosslinked PS-b-PEG block copolymers and PbO doping occurred in the PS-b-PEG-BN. Nanocomposite materials are excellent choices for achieving radiation protection objectives for gamma rays. These materials are particularly advantageous as a shielding substance for transporting radiation sources and as an insulating substance for radioactive waste administration facilities or the building industry. When it comes to boosting the hardness, durability, and radiation absorption capacities of the shielding materials, the connecting of several sorts of contributions (such as cement, polymer, and metal oxide, among others) is of the utmost importance. As a result of their low cost and low weight, polymer structures are a significant class of substances that are utilized in radiation shielding research. In addition, polymer structures will be the starting point for many different types of research utilizing composites acquired by suffixing micro or nano-oxide, etc., to investigate radiation attenuation both theoretically and experimentally.

2.3 The gamma-ray shielding properties of the polymer-nanostructured selenium dioxide (SeO₂) and boron nitride (BN) nanoparticles

The gamma-ray shielding properties of crosslinked PS-b-PEG block copolymers combined with nanostructured SeO₂ and BN nanoparticles were investigated by Cinan et al. [2] in their work. The PS-b-PEG copolymer as well as nanostructured SeO₂ and BN particles, all had a substantial impact on the enhancement of the resistance of the nanocomposites, and the samples with high additive rates demonstrated superior resistance than the other nanocomposites. As a result of the accomplishments, it is possible to conclude that the polymer-based nanocomposites can be utilized as a viable option in the gamma-irradiation-shielding sector of the industry. Their nanocomposites’ irradiation properties were studied using rays from a ¹⁵²Eu source in an HPGe detector setup, and the results were evaluated using Gamma Vision software. In addition, the theoretical calculus was used to determine all of the radiation shielding factors, and these were compared to the findings of the experiments. Because different rays of different energy and wavelengths have varied interactions with the atoms in the material, the ¹⁵²Eu radioactive source was utilized to offer the most thorough data. The comparability between the experimental findings and the theoretical predictions was found to be satisfactory in all of the nanocomposites.

The PS-b-PEG copolymer as well as nanostructured SeO₂ and BN particles had a key role in the enhancement of the resistance of the nanocomposites, and the samples with high additive rates displayed superior resistance than the other nanocomposites did. Figure 3 presents SEM images of the crosslinked PS-b-PEG block copolymer with BN nanocomposites. BN nanoparticles mixed homogeneously with PS-b-PEG block copolymer. There are roughnesses, particles, pores, and elevations on the surface. Based on the results that were obtained, it is possible to conclude that polymer-based nanocomposites are a good option for use in the gamma-irradiation-shielding discipline in many different applications (such as flexible and durable gamma-radiation-protective systems for the transportation of radioactive materials, isolation for the operations of radioactive waste, and radiation services in hospitals, nuclear power plants (NPPs), the defense industry, the building industry, and many other applications). The theoretical and experimental mL values of the studied nanocomposites were found to be in satisfactory concordance with one another. In particular, the PS-b-PEG block copolymers blended with the nanostructured SeO₂ and BN particles’ nanocomposite matrix resulted in a significant enhancement in the possibilities of reciprocal influence between the arriving gamma rays and the shielding nanocomposite atoms. This was the case since the PS-b-PEG block copolymers were blended with the nanocomposite matrix. They can conclude that the nanocomposites they have researched can also be employed as materials that guard against low and large doses of gamma radiation. They demonstrated that the μ_L rates tended to fall when the gamma energy was increased. It was determined that the experimental and theoretical μ_L rates exhibited good harmony and improved shielding behavior with the change in the polymer type utilized to manufacture gamma-ray-absorbing nanoparticles. This was one of the conclusions that were reached. Moreover, they discovered that the gamma-ray protection properties of the nanocomposites increased when the amounts of nanostructured SeO₂ and BN particles contained in the nanomaterials were adjusted. This was another finding made by the researchers. The μ_m values of the PBSNC5, PBSNC9, PBSNC6, PBSNC8, and PBSNC12 nanocomposites [2] were lower than the mm values of their respective copolymers when the composites including copolymers, SeO₂, and BN nanoparticles were tested at 121.782 keV. These nanocomposites had μ_m values of 0.151, 0.142, 0.242, 0.263, and 0.329, respectively. At this energy, the mm values of the PSNC6 and PSNC11 copolymers [2] dropped from 0.283 to 0.151 and from 0.177 to 0.142, respectively, after the addition of 50 wt% nanostructured BN to the PSNC6 and PSNC11 copolymers. This change was caused by the addition of nanostructured BN. It was determined that the experimental and theoretical μ_m rates exhibited good harmony; more specifically, it was determined that the PS-b-PEG copolymers combined with nanostructured SeO₂ and BN particles in a nanocomposite matrix showed good attenuation and protective outcomes against gamma irradiation. It is possible to conclude that the nanocomposites have the potential to be used as shielding materials against low and high gamma doses in a variety of settings. For all of the nanocomposites’ outcomes, it has been thoroughly emphasized that the experimental and theoretical values demonstrate changes when the type of copolymer that was used to build the nanomaterial for the attenuation of and protection against the impacts of gamma rays is changed. These variations can be seen in both the attenuation and protection that the nanomaterial provides. In addition to this, it was observed that the radiation shielding performance of the other nanocomposites increased when the nanostructural proportions of SeO₂ or BN particles included in the nanocomposites were raised. When the μ_L and μ_m values of all of the nanocomposites are examined, it is clear that the nanostructured composites cultured in this work demonstrate significant and reliable outcomes in terms of radiation absorption and protection. These findings can be seen when the nanocomposites are examined.

Figure 3.

SEM photographs of the crosslinked PS-b-PEG (10,000) block copolymer+BN nanocomposite (50% PS-PEG (10,000)+50% BN+0% PbO): (a) PS-PEG (10,000)-BN-S0 (12,000× magnification); (b) PS-PEG (10,000)-BN-S0 (4480× magnification).

The HVL, TVL, MFP, and RPE rates that have been determined for the nanocomposites are the factors that have the largest impact on the gamma-shielding effectiveness. The gamma-ray shield’s qualities have a greater influence on the environment when the HVL, TVL, and MFP rates are reduced. In addition, the performance of the polymer-based nanocomposites that were manufactured to develop the shield for protection against gamma rays over a wide energy range may be seen by calculating the RPE rates. This will show the performance of the nanocomposites. Additionally, it was discovered that the gamma irradiation protective properties of the nanocomposites rose when the amounts of nanostructured SeO₂ and BN particles present in the nanomaterials were increased. This was another finding that was made. The TVL rates of the PS-b-PEG block copolymers blended with the nanostructured PbO particles changed from 5.799 cm to 30.725 cm. On the other hand, the TVL rates of the PS-b-PEG (1000) block copolymer blended with the nanostructured SeO₂ particles did not change. Furthermore, the HVL rates of the PS-b-PEG copolymers blended with the nanostructured PbO and BN particles changed from 0.967 cm to 7.347 cm (for 15% PS-b-PEG (10,000) copolymer, 15% nanostructured BN, and 70% PbO particles) [8], and the HVL values of the PS-b-PEG (10,000) block copolymer blended with the nanostructured SeO₂ and BN particles changed from 0.843 cm to 7.203 cm (for 15% PS-b-PEG (10,000) copolymer, 15% nanostructured BN, and 70% SeO₂ nanoparticles). To be more specific, the nanostructured SeO₂ additive decreased the thickness while simultaneously improving the radiation absorption efficiency. In addition, the ability of the polymer-based nanocomposites that were designed to detect the attenuation behaviors of the gamma rays in a wide energy range can be detected by computing the RPE rates. When confronted by gamma rays, the copolymers that were combined with nanostructured SeO₂ and BN nanocomposites had excellent shielding efficacy (see Figure 4). This conclusion may be drawn from all of the researchers’ findings. The shielding properties of these composites were comprehensively obtained with the ¹⁵²Eu gamma radioisotope source by detecting the outputs of nanostructured SeO₂ and BN particles blended or unblended in PS-b-PEG-based composite tablets with the experimental system. The infrastructure of this system was created with theoretical calculations via the radiation parameters. In addition to this, the morphological and temperature degradation features were examined. It has been observed that increasing the amount of nanostructured SeO₂ and BN particles in PS-b-PEG copolymer-structured composite materials results in an increase in the amount of radiation shielding and protection from dangerous gamma rays given by the materials. In this context, the behavior of SeO₂ and BN blended and unblended nanocomposites against a gamma radioisotope source with a wide energy range was investigated. Additionally, an application-oriented study that can be used in fields such as nuclear technology was carried out, and the results of this study can contribute to the scientific literature. The TEM photos also revealed another significant finding, which was that the addition of BN nanoparticles to the nanocomposite brought about a discernible shift in the distribution as well as the particle structure of the SeO₂ nanoparticles present in the composite.

Figure 4.

The μ_m rates and HVL values of the PS-b-PEG copolymers blended with the nanostructured SeO2 and BN particles under a wide range of gamma irradiation energies.

2.4 Design and fabrication of high-density borated polyethylene nanocomposites as a neutron shield

Mortazavi et al. [9] have shown that neutron shielding using polyethylene composites containing boron can be accomplished in a very efficient manner. Their investigation is centered on the manufacturing of borate polyethylene nanocomposites. The purpose of this research is to develop a radiation shield that can be employed effectively in situations in which the user is subjected to both neutron and gamma radiation. They started by making borate polyethylene shields that had 2 and 5% by weight of boron nanoparticles, and then, they compared the neutron attenuation of those shields to that of pure polyethylene. In order to determine the amount of attenuation that Am-Be neutrons experience when traveling through the shields, they used polycarbonate sheets. The mean (standard deviation) of the number of traces induced by neutrons traveling through shields was 1.048810 3 128.98 for polyethylene with 5% by weight, and 289.5610 3 1.1972, and 1.534010 3 206.52 for polyethylene with 2% by weight boron nanoparticles and pure polyethylene. The tensile strength of borate polyethylene nanocomposites was found to be greater than that of pure polyethylene. Neutron attenuation was compared between a borate polyethylene nanocomposite that had 5% by weight boron in it and pure polyethylene, and the results showed that there was a statistically significant difference between the two. However, there was not a statistically significant difference between having 5% by weight of boron borate in a polyethylene nanocomposite and having 2% by weight of boron. It was also established in this research that the tensile strengths of boron carbide nanocomposites are significantly greater than those of pure polyethylene. It is important to note that the findings of Mortazavi et al.’s earlier research on photon shielding show that the use of nano-sized materials in radiation shielding can only provide better attenuation results in very particular circumstances, such as a limited photon energy range or a limited concentration of nanomaterials in the matrix. This is something that should be kept in mind.

2.5 The nuclear shielding of iron-boron alloys

Iron-boron alloys play a significant role in powder metallurgy, and Aytac and coworkers [10] looked at their nuclear radiation shielding properties for this study. When bombarded with ¹⁵²Eu, Fe(100-x)B(x) alloys (where x is 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20) produce photons with energies of 0.0810, 0.1218, 0.2764, 0.3029, 0.3560, 0.3443, 0.3839, and 0.7789 MeV, respectively. The photon intensities were measured with an Ultra-Ge detector. Half-value layers, mean free routes, effective atomic numbers, and effective electron densities were all computed using experimentally observed μ_m. The results demonstrate that the HVL and MFP values are best for the Fe-B alloy with 20% boron. Research has demonstrated that the addition of boron does not improve Fe-B alloys’ photon-shielding properties. However, it was shown to be quite effective in terms of gamma attenuation in the chosen energy range when compared to previously reported shield materials. Neutron dose transmission studies were conducted as well, with removal cross-sectional values (∑R) determined. In contrast to their gamma-shielding properties, Fe-B alloys’ neutron reduction capability increased with increasing boron content. The findings from each of the gamma shielding parameters demonstrated that an increasing quantity of boron had a detrimental effect on the alloys’ capacity to cut down on gamma radiation. In addition to that, measurements of the equivalent neutron dosage were carried out, and the effective removal cross sections of the alloys were gathered. Based on these factors, it was determined that the alloy’s neutron-holding capacity rose along with the percentage of boron present in the alloy. It is anticipated that as a consequence of this, it will be possible to conclude that Fe-B alloys are more effective at absorbing neutron radiation than gamma radiation.

2.6 Boron nitride nanosheet-reinforced WNiCo-FeCr HEAs

WNiCo-FeCr high entropy alloys (HEAs) were the subject of research conducted by Kavaz et al. [11], who investigated the synthesis and complete characterization of these alloys. These alloys were reinforced with newly created boron nitride nanolayers (BNNSs). In this work, a comprehensive investigation was conducted into the effect of B₄C on the structural, physical, mechanical, and nuclear protective features of synthesized HEAs. The investigation focused on the effect of B₄C’s monotonous behavior modifications. They were able to ascertain the characteristics of protection against nuclear radiation through the use of experimental gamma-ray and neutron assemblies. In addition, the properties of nuclear radiation shielding for gamma rays and fast neutrons were carefully compared with the properties of many other kinds of shielding materials, both those already in use and those of the next generation. They concluded that an elevated level of B₄C directly adds to the shielding qualities of nuclear radiation after reviewing the relevant evidence. They state that the B₄C that is formed within the structure of BNNS will contribute to the overall properties of HEAs. This is highly essential for nuclear applications, as HEAs are now being examined as a component of potential future nuclear reactors. In addition, they concluded that B₄C is a versatile material that can be utilized in settings where the mechanical and nuclear shielding qualities need to be improved for a variety of radiation intensities. This led them to the conclusion that B₄C is a versatile material.

2.7 B₄C particle-reinforced Inconel 718 composites

Gokmen [12], in his work, wanted to offer a computational tool that would perform calculations of critical physical variables for the gamma-ray attenuation in the B₄C (0.25 wt%) particle-reinforced Inconel 718 superalloy. Specifically, the purpose of this study was to determine the gamma-ray attenuation in the material. It was the first time that the shielding qualities of the B₄C (0.25 wt%) particle-reinforced Inconel 718 superalloy were investigated for use in nuclear technology as well as other technologies such as nanotechnology and space technology. The relationship between the weight percentage of the B₄C component in these superalloy materials and the attenuation of gamma rays was investigated. The LAC, MAC, Exposure Buildup Factors (EBF), TVL, HVL, MFP, Z_eff, and fast neutron removal cross sections (FNRC) values of the B₄C (0e25 wt%) particle-reinforced Inconel 718 superalloy composites (which contains special alloy elements such as Ni, Cr, Nb, Mo) were theoretically calculated for the first time in order to evaluate the effectiveness of gamma and neutron radiation shielding using the PSD software. The attenuation performance of the materials, which may be utilized as shielding materials, improved as a result of a decrease in the weight fraction of the B₄C compound in the Inconel 718 superalloy composites, as evidenced by the computed values of the MAC. The MFP, HVL, and TVL values were found to increase as the gamma-ray energy and the weight percent of the B₄C component found in the Inconel 718 superalloy composites was increased. This was observed to be the case. This occurred because of the density as well as differences in the chemical makeup of certain superalloy compounds. Due to the greater values of MFP, HVL, and TVL, it can be deduced that thicker materials are necessary to attenuate radiation to a level that is considered safe. Because of this, it is preferable to choose materials with lower HVL values rather than those with higher HVL values in order to cut down on both the cost and the size. As a consequence of this, the Inconel 718 superalloy materials with B₄C addition are incapable of successfully absorbing a wide variety of gamma rays. This is because these materials have a low gamma absorption cross section. Because of this, the superalloy Inconel 718 material known as S6 which contains B₄C in a weight percentage of 25% was discovered to be the most effective neutron shielding material. Because the energy of the incident gamma rays influences both the selection of the shielding material and the determination of the required thickness of the shielding material, this study reveals that each quantity is dependent on the energy.

2.8 Borate glasses

The expanding applications of gamma radiation in fields such as health, industry, and agriculture call for the research and development of radiation shielding materials that are see-through. According to Kirdsiri et al. [8], glass materials are perfect for this purpose since they can be recycled completely, they do not have an opaque appearance, and they can be modified and transformed by adding new components.

Nuclear radiation attenuation and mechanical characteristics were inspected by Lakshminarayana et al. [13] for 10 lithium bismuth borate glasses with varying levels of Bi₂O₃ concentration (ranging from 10 to 55 mol% and denoted as glasses A to J). This was done in order to gain an understanding of how these properties would change with an increase in Bi₂O₃ content. At a selection of twenty-five energies ranging from 15 KeV to 15 MeV, photon shielding abilities in respect to μ, μ/ρ, Z_eff, N_eff, HVL, TVL, MFP, and RPE have been investigated. At each energy level, it was found that the μ/ρ values that were calculated using theoretical (Py-MLBUF [14] and WinXCOM [15]) and computational (MCNPX [16], FLUKA [17, 18], and PHITS codes [19]) methods were in qualitative agreement with one another. For example, each Py-MLBUF, WinXCOM, MCNPX, FLUKA, and PHITS algorithms got a different /g value for sample J at 0.6 MeV energy. These values were 0.119, 0.1186, 0.1126, 0.1183, and 0.1174 cm²/g, respectively.

In this research work, Almuqrin et al. [20] aim to evaluate the radiation shielding capabilities of a Yb³⁺-doped calcium borotellurite glass system as part of their investigation. The system’s fundamental components are CaF₂–CaO–B₂O₃–TeO₂–Yb₂O₃, but for convenience’s sake, one is referring to it as TeBYbn. It was determined what would happen if the amount of TeO₂ in the glasses was increased from 10 to 54 mol% by experimenting with five distinct combinations of compositions and densities. Investigation into the μ_m (μ/ρ) of the samples was carried out with the help of the Phy-X/PSD program [21]. The mass attenuation coefficients were calculated theoretically by using an online program that was designed to calculate shielding characteristics. Other metrics, such as the μ_L, transmission factor (TF), RPE, Z_eff, and MFP, were then computed and studied after that. TeBYb5, the glass with the highest TeO₂ content, was demonstrated to have the highest μ/ρ; however, at higher energies, the variations between the values became essentially insignificant. It was discovered that density increases with density, such as going from 0.386 to 0.687 cm⁻¹ for TeBYb1 and TeBYb5 at 0.284 MeV, respectively. It was determined that there is an inverse association between the thickness of the sample and the TF because it was discovered that samples with a thickness of 1.5 cm had the lowest TF. Because both the HVL and the TVL of the samples declined as the density of the samples dose, one can conclude that TeBYb1 is the least effective of all of the glasses that were studied. These five samples were able to demonstrate their effectiveness as radiation shields by having an MFP that was lower than that of certain other types of shielding glasses. TeBYb5 appeared to have the greatest capacity to attenuate photons based on the parameters that were determined.

Lakshminarayana et al. [22] investigated the gamma-ray and neutron attenuation properties of both the B₂O₃-Bi₂O₃-CaO and the B₂O₃-Bi₂O₃-SrO glass systems in their research. This was done for both of the glass systems. Within the energy range of 0.015 to 15 MeV, linear attenuation coefficients (μ) and mass attenuation coefficients (μ/ρ) were estimated by using the Phy-X/PSD program. The obtained numbers fit up quite well with the respective simulation results computed by the MCNPX, Geant4 [23, 24, 25], and Penelope [26] programs. The inclusion of Bi₂O₃, rather than B₂O₃/CaO or B₂O₃/SrO, results in increased gamma-ray shielding competency. This is indicated by an increase in the Z_eff as well as a decrease in the HVL, TVL, and MFP. Within the range of 0.015 to 15 MeV, a geometric progression (G-P) fitting approach was utilized to determine EBFs and energy absorption buildup factors (EABFs) at 1 to 40 mfp penetration depths (PDs). The RPE values that have been computed show that they have a high capacity for shielding photons with lower energies, comparatively greater density (7.59 g/cm³), larger μ/ρ, Z_eff, equivalent atomic number (Z_eq), and RPE, along with the lowest HVL, TVL, MFP, EBFs, and EABFs derived for 30B₂O₃-60Bi₂O₃-10SrO (mol%) glass, implying that it could be an excellent gamma-ray attenuator. Additionally, 30B₂O₃-60Bi₂O₃-10SrO (mol%) glass holds a commensurably bigger macroscopic removal cross section for fast neutrons.$\sum _R=0.1199c{m}^{-1}$ obtained by applying Phy-X/PSD for fast neutron shielding, owing to the presence of a larger wt% of ‘Bi’ (80.6813 wt%) and moderate “B” (2.0869 wt%) elements in it. Because it has a high weight percentage of the “B” element, the sample with the composition 70B₂O₃-5Bi₂O₃-25CaO (mol%) (B: 17.5887 wt%, Bi: 24.2855 wt%, Ca: 11.6436 wt%, and O: 46.4821 wt%) has a high potential for the capture or absorption of thermal or slow neutrons and intermediate energy neutrons.

During the course of their research, Madbouly and colleagues [27] looked at bismuth-borophosphate glasses. One type of glass known as borophosphate glass contains phosphorus and boron oxide as components. Borophosphate glass is an important category of glass that can be distinguished by several useful qualities that it contains. Borophosphate glass has been demonstrated to have excellent ionic conductivity, and its preparation is very straightforward. Despite its low melting point and high glass-forming capacity, the application of borophosphate glass has been limited because of its hygroscopic character. This is even though it has a relatively low melting point. It is recommended that a heavy metal oxide (HMO) be added to the produced glass in order to increase its potential for radiation shielding. The metal oxide with the highest density is known as HMO. In addition to this, the high atomic number of Bi contributes to the enhanced gamma shielding capabilities of the glass [28]. In applications that make use of radiation, protective glasses are increasingly being utilized to absorb incoming photons that could potentially harm employees and patients in the area surrounding the radioactive source. Radiation is currently being utilized in hundreds of applications spanning a variety of industries, such as the medical area and the production of energy. Even though radiation has certain positive effects, extra caution is required while working with radioactive sources since photons with a high energy level pose a significant threat to the human body. In this work, they investigate the effect that Bi₂O₃ has on the structure of borophosphate glasses as well as the optical and radiation shielding properties of these glasses. They measured the photon transmissions, μ_Ls, HVL, TVL, and MFP values of bismuth-borophosphate glasses experimentally. The gamma-ray energies they employed were 662, 1173, 1275, and 1333 keV. After that, the results of the measurements were checked against the FLUKA code. The conclusions from the FLUKA code were in good agreement with the results of the experiments. In addition, the data demonstrate that increasing the amount of Bi₂O₃ in the glass network improves the quality of shielding. According to the data they currently have, the absorbance increases in tandem with a rising Bi₂O₃ level. Bismuth-borophosphate glasses have excellent gamma-ray shielding capabilities, making them a good choice for shielding applications.

For shielding applications against the energies emitted by ²²Na and ¹³¹I isotopes, Al-Buriahi [29] used FLUKA to examine the radiation of gamma and fast-neutron shielding performance of borate glasses containing zinc, bismuth, and lithium (as modifier). Glasses ranging from 0 to 20 mol% xBi₂O₃-(25-x) Li₂O-60B₂O₃-15ZnO were analyzed. For the ²²Na isotope, the simulations are in run for energies of 0.511 and 1.275 MeV, and for the ¹³¹I isotope, the energies of 0.365, 0.637, 0.284, and 0.723 MeV. In addition, the report explored the borate glasses’ capacity to deflect fast neutrons, thermal neutrons, and charged particles. The results show that the ²²Na isotope emits photons with energies as low as 0.284 MeV and that the borate glasses of BLBZ1, BLBZ2, BLBZ3, BLBZ4, and BLBZ5 have values of 0.282, 0.349, 0.887, 1.103, and 1.397 cm⁻¹ and values of 0.108, 0.198, 0.251, 0.286, and 0.310 cm²/g. At 0.2 MeV, the borate glasses BLBZ1, BLBZ2, BLBZ3, BLBZ4, and BLBZ5 had maximum total SP of electron interaction values of 2.292, 2.076, 1.949, 1.865, and 1.807 MeV cm²/g, respectively. Furthermore, for the current borate glass samples, the effect of Bi₂O₃ content on the dosage rate was quite minimal. The removal cross sections for fast neutrons in the borate glasses of BLBZ1, BLBZ2, BLBZ3, BLBZ4, and BLBZ5 were 0.112, 0.111, 0.103, 0.100, and 0.106 cm⁻¹, respectively. It is concluded that BLBZ5 glass has the potential to be developed as a viable option for gamma applications. Table 1 shows the glass code, chemical formula, and weight fraction (wt %) for each component in the current glass specimens.

Glass code	Chemical formula	wt%				Bi
		Li	B	O	Zn
BLBZ1	60B2O3-15ZnO-25Li2O	0.05648	0.21112	0.57280	0.15960
BLBZ2	60B2O3-15ZnO-20Li2O-5Bi2O3	0.03335	0.15583	0.44200	0.11780	0.25102
BLBZ3	60B2O3-15ZnO-15Li2O-10Bi2O3	0.01982	0.12349	0.36550	0.09335	0.39784
BLBZ4	60B2O3- 15ZnO-10Li2O-15 Bi2O3	0.01094	0.10226	0.31529	0.07731	0.49420
BLBZ5	60B2O3-15ZnO-5Li2O-20Bi2O3	0.00467	0.08726	0.27981	0.06597	0.56229

Table 1.

Glass code, chemical formula, and weight fraction (wt%) for each component in the current glass specimens.

Borotellurite glasses with the molar compositions of 60TeO₂–20B₂O₃–(20-x)Bi₂O₃–xPbO, where x = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 mol%, were synthesized with the help of a typical melt quenching procedure and investigated in terms of their physical, optical, structural, and gamma shielding capabilities. Marzuki and colleagues [30] researched these spectacles. After being mixed, the powder was subsequently melted in an electric furnace at a temperature of around 1000°C for approximately 60 minutes. After being quenched by pouring it into a preheated parallel plate brass mold, the molten metal was subsequently annealed at 350°C for roughly 180 minutes before being cooled to room temperature at a rate of 1°C per minute. When the concentration of PbO is increased from 0 to 10 mol%, the density of the current samples decreases from 6.08 to 5.93 g/cm³, and the molar volume decreases from 33.37 to 30.27 cm³/mol. This is because there is a decrease in the concentration of the element Bi₂O₃. Because PbO is used throughout the network rather than Bi₂O₃, the optical packing density has increased from 71.91 to 72.67% as a direct result of this change. When the concentration of PbO increases, the refractive index, molar refractivity, and ionic polarizability all decrease. Specifically, the refractive index drops from 1.9137 to 1.8306, the molar refractivity drops from 18.531 to 16.884 cm³, and the ionic polarizability drops from 7.3534 to 6.7000 3. An increasing fraction of the glass network will be formed of [TeO₃] (tp) and [TeO₃+1] polyhedra as the amount of lead oxide present in the glass increases. The Phy-X PSD software [21] was used in the theoretical research of the gamma radiation shielding qualities, and the photon energy was varied from 0.015 to 15 MeV throughout the study. When considering all glasses, the values of the μ_L that are observed to be the highest are found at 0.015 MeV, while the values that are observed to be the values that are observed to be lowest are found around 5 MeV. At this stage of the gamma photon-electron interaction, the formation of pairs starts to take precedence over everything else. When there is an increase in the concentration of PbO, there is a corresponding decrease in the concentration of Bi₂O₃; this causes the LAC values to decrease across all photon energies. The values of the μ_L change from a high of 413.2183 cm⁻¹ to a low of 12.4962 cm⁻¹ when the potential energy is 0.015 MeV. This dependence on composition is at its most pronounced for photon energy in the range of 0.015–0.04 MeV. When the energy is greater than 0.04 MeV, this dependence is greatly diminished. The outcomes of this experiment at μ_L suggest that using Bi₂O₃ as a gamma shielding material rather than PbO is likely to give better results. The experiment was conducted to investigate this hypothesis.

The study conducted by Mahmoud et al. [31] sought to examine the impact of Pr³⁺ ions on the structural, optical, and gamma-ray shielding characteristics of borosilicate glasses. This study produced a set of borosilicate glass specimens comprising five distinct samples. The samples were composed of a mixture of (55-x) B₂O₃, 15SiO₂, 20CaO, 10Li₂O, and xPr₆O₁₁. The objective of the study was to investigate the effects of Pr₆O₁₁ on the structural, optical, and X-ray shielding characteristics of borosilicate glass. The findings obtained from the UV-Vis IR spectrometer indicate a reduction in the direct energy gap from 3.508 to 3.304 eV, which is accompanied by an elevation in the Urbach energy from 0.335 to 0.436 eV. These changes are observed as the concentration of Pr₆O₁₁ is increased from 0 to 1 mol%. Furthermore, the Monte Carlo simulation outcome about the shielding characteristics of X-rays illustrates an increase in the micrometer values as a result of the minor amounts of Pr₆O₁₁ reinforcement. At an energy level of 103 keV, the micrometer values experienced a 161% increase, while the 0.5 values decreased by 62% upon increasing the Pr₆O₁₁ concentration from 0 to 1 mol%. At higher intermediate and high-energy gamma (E) values, the gamma-ray shielding properties of the produced glasses exhibit a negligible improvement. This study posited that the samples under investigation are suitable for shielding photons possessing energies that are less than 511 keV.

3. Conclusions

Nanocomposite materials are excellent choices for achieving radiation protection objectives for gamma rays. These materials are particularly advantageous as a shielding substance for the transportation of radiation sources and as an insulating substance for radioactive waste administration facilities or the building industry. As a result of their low cost and low weight, polymer structures are a significant class of substances that are utilized in radiation shielding research. A boron polymer that contains phenylethenylboronic acid has been shown to have a significant neutron absorption cross section. They assessed several different metrics of coherent and incoherent neutron scattering for a variety of boron polymers. In addition, polymer structures will be the starting point for many different types of research utilizing composites acquired by suffixing micro- or nano-oxide, etc., to investigate radiation attenuation both theoretically and experimentally. It has been observed that increasing the amount of nanostructured SeO₂ and BN particles in PS-b-PEG copolymer-structured composite materials results in an increase in the amount of radiation shielding and protection from dangerous gamma rays given by the materials. In this context, the behavior of SeO₂ and BN blended and unblended nanocomposites against a gamma radioisotope source with a wide energy range was investigated. It was also established that the tensile strengths of boron carbide nanocomposites are significantly greater than those of pure polyethylene. The findings from each of the gamma shielding parameters demonstrated that an increasing quantity of boron had a detrimental effect on the alloys’ capacity to cut down on gamma radiation. In addition to that, measurements of the equivalent neutron dosage were carried out, and the effective removal cross sections of the alloys were gathered. Based on these factors, it was determined that the alloy’s neutron-holding capacity rose along with the percentage of boron present in the alloy. It is anticipated that as a consequence of this, it will be possible to conclude that Fe-B alloys are more effective at absorbing neutron radiation than gamma radiation. It is concluded that B₄C is a versatile material that can be utilized in settings where the mechanical and nuclear shielding qualities need to be improved for a variety of radiation intensities. This led them to the conclusion that B₄C is a versatile material. The Inconel 718 superalloy materials with B₄C addition are incapable of successfully absorbing a wide variety of gamma rays. This is because these materials have a low gamma absorption cross section. Because of this, the superalloy Inconel 718 material known as S6 which contains B₄C in a weight percentage of 25% was discovered to be the most effective neutron shielding material. Because the energy of the incident gamma rays influences both the selection of the shielding material and the determination of the required thickness of the shielding material, this study reveals that each quantity is dependent on the energy. The boron-doped nanoparticles and boron-based polymers can be effectively used as potential radiation shielding materials in daily life and work-life environments. The use of additives in the boric-oxide matrix is also another promising approach for the development of glass-based composites for radiation shielding materials.

Acknowledgments

The authors thank to Karadeniz Technical University for their support. In addition, the authors also would like to express gratitude to Bilkent University UNAM for their kind hospitality.