Estimation of Dose Enhancement for Inhomogeneous Distribution of Nanoparticles: A Monte Carlo Study

High atomic number nanoparticles are of increasing interest in radiotherapy due to their significant positive impact on the local dose applied to the treatment site. In this work, three types of metal nanoparticles were utilized to investigate their dose enhancement based on the GATE Monte Carlo simulation tool. Gold, gadolinium, and silver were implanted at three different concentrations to a 1 cm radius sphere to mimic a cancerous tumor inside a 10 × 10 × 30 cm3 water phantom. The innermost layer of the tumor represents a necrotic region, where the metal nanoparticles uptake is assumed to be zero, arising from hypoxic conditions. The nanoparticles were defined using the mixture technique, where nanoparticles are added to the chemical composition of the tumor. A directional 2 × 2 cm2 monoenergetic photon beam was used with several energies ranging from 50 keV to 4000 keV. The dose enhancement factor (DEF) was measured for all three metal nanoparticles under all beam energies. The maximum DEF was ~7 for silver nanoparticles with the 50 keV beam energy at the highest nanoparticle concentration of 30 mg/g of water. Gold followed the same trend as it registered the highest DEF at the 50 keV beam energy with the highest concentration of nanoparticles at 30 mg/g, while gadolinium registered the highest at 100 keV

Experimental investigation and machine learning modeling using LSTM and special relativity search of friction stir processed AA2024/Al2O3 nanocomposites

In this study, the friction stir technique is proposed to process aluminum nanocomposites reinforced with alumina nanoparticles. The effects of different processing parameters, including spindle speed (900–1800 rpm), feed (10–20 mm/min), and number of passes (1–3) on the mechanical and dynamic properties of the processed samples were investigated. The investigated properties were ultimate tensile strength, yield strength, natural frequency, and damping ratio. An advanced machine learning approach composed of a long short-term memory model optimized by a special relativity search algorithm was developed to predict the properties of the processed samples and different processing conditions. The adequacy of the developed model was tested and compared with three other machine learning models; the predicted properties were in good agreement with the measured properties. The developed model outperformed other tested models and was found to be a powerful prediction tool for predicting processing conditions to obtain high-quality nanocomposite samples. The model succeeded in predicting the ultimate tensile strength, yield strength, natural frequency, and damping ratio with good R2 of 0.912, 0.952, 0.951, and 0.987, respectively. The obtained results showed that the samples' damping ratio and loss factor increase with the number of passes, while the natural frequency, shear modulus, and complex modulus decrease with the number of passes. Thus, friction stir processing can be used to improve the damping properties of materials

The Effect of Hybrid B₄C and Si₃N₄ Nanoparticles on the Mechanical and Physical Properties of Copper Nanocomposites

This study investigated the effects of reinforcing pure copper with hybrid B4C and Si3N4 nanoparticles on the mechanical and physical properties of the nanocomposite matrix. The composite matrix was prepared using the powder metallurgy (PM) method, allowing uniform nanoparticle dispersion within the copper matrix. The PM method was a practical approach for achieving a homogeneous and good dispersion of the reinforcing particles in the matrix while controlling the porosity and improving the microstructure of the fabricated composite matrix. The addition of B4C and Si3N4 are both very hard and dense materials. When added to a material, they can fill voids and reduce porosity. This can lead to significant improvements in the material’s mechanical properties. The study found that adding hybrid B4C and Si3N4 nanoparticles enhanced the microhardness and mechanical properties of the nanocomposites. The improvements in the mechanical and physical properties of such composites containing 5% B4C were 21.6% and 18.4% higher than the copper base alloy. The findings suggest that including ceramic particles is a viable strategy for enhancing the mechanical characteristics of copper in its pure form. For example, adding 5% B4C particles to copper resulted in a 23% increase in Young’s modulus of the material while reducing electrical conductivity by 4.6%. On the other hand, the hybrid composite Cu/5%B4C + 2.5%Si3N4 showed a 32% improvement in Young’s modulus and 71% in the microhardness value compared to the base metal. This makes it a promising option for various engineering applications, such as high-performance electrical contacts and bearings

A virtual laboratory for radiotracer and sealed-source applications in industry

Radioactive sealed sources and radiotracer techniques are used to diagnose industrial process units. This work introduces a workspace to simulate four sealed sources and radiotracer applications, namely, gamma scanning of distillation columns, gamma scanning of pipes, gamma transmission tomography, and radiotracer flow rate measurements. The workspace was created in Geant4 Application for Tomographic Emission (GATE) simulation toolkit and was called Industrial Radioisotope Applications Virtual Laboratory. The flexibility of GATE and the fact that it is an open-source software render it advantageous to radioisotope technology practitioners, educators, and students. The comparison of the simulation results with experimental results that are available in the literature showed the effectiveness of the virtual laboratory

Production of actinium-225 from a (n,p) reaction: Feasibility and pre-design studies

Actinium-225 is used in nuclear medicine for the treatment of malignant tumours. It can be applied to produce Bi-213 in a reusable generator or can be used alone as an agent for radiation therapy, in particular for targeted alpha therapy. However, the availability of Ac-225 for worldwide use, particularly in low- and middle-income countries, is limited. We present a feasibility study employing GATE, an open-source Monte Carlo simulation toolkit, on the production of Ac-225 from a neutron generator. This work suggests that a design consisting of three concentric cylinders, the innermost a Cf-252 neutron source, the middle nickel cylinder acting as a proton-producing target and the outer cylinder a RaCl2 target may provide a feasible design outline for an Ac-225 generator

Improving the polyethylene oxide/carboxymethyl cellulose blend's optical and electrical/dielectric performance by incorporating gold quantum dots and copper nanoparticles: nanocomposites for energy storage applications

Herein, nanocomposite polymer electrolyte films were prepared from the blend of two polymers, polyethylene oxide (PEO) and carboxymethyl cellulose (CMC), stuffed with various contents of gold quantum dots (AuQDs) and copper nanoparticles (CuNPs) as hybrid nanofiller via the solution casting method. AuQDs were prepared using laser ablation in liquid (LAL). TEM images showed that the average size of AuQDs is nearly 6.21 nm with a spherical shape. The effects of AuQDs and the hybrid nano-filler (AuQDs and CuNPs) on the PEO/CMC blend structural, optical, and electrical/dielectric characteristics have been investigated and discussed. XRD results revealed that the crystallinity degree of the nanocomposite samples decreased with increasing AuQDs/CuNPs content. Also, UV–Vis spectroscopy analysis uncovered that the optical energy gap reduced as the hybrid nanofillers' content increased. At room temperature, the electrical impedance spectroscopy (EIS) measurements showed that the hybrid nanofiller loading increases the electrolyte films’ electrical conductivity. In the dielectric properties, space charges polarization revealed higher values, where the dielectric constant (ε′) increased at lower frequency regions. The Nyquist diagram showed a semicircular shape at the lower frequencies part with a linear shape at the higher frequencies part with decreasing radius; two equivalent circuit models could be the best fit. These results suggest that these nanocomposite electrolyte films could be candidates for capacitors and flexible energy storage devices