Shielding features of concrete types containing sepiolite mineral: comprehensive study on experimental, XCOM and MCNPX results

Natural sepiolite mineral is a naturally occurring clay form belonging to a part of layered silicate. Because of its advantages such as low production cost, light-weight and convenient, it may be selected as an alternative shielding material to others. Radiation shielding performances of some concretes to sepiolite and B4C addictive have been researched reported in a wide energy region of 0.08–1.333 MeV using experimental data, MCNP and XCOM. The simulated data obtained by MCNPX are discussed and compared with the experimental results as well as with the XCOM results. The simulations match the experiments very well except for S3 sample. From the measurement, the maximum gamma-ray attenuation was detected in the concrete specimen with 10% sepiolite (S1) while the minimum attenuation of gamma-ray was noted in the concrete specimen with 30% sepiolite (S3). The addition of sepiolite mineral to concretes may be an alternative option that can be used in several radiation protection applications

A rapid and direct method for half value layer calculations for nuclear safety studies using MCNPX Monte Carlo code

Half Value Layer calculations theoretically need prior specification of linear attenuation calculations, since the HVL value is derived by dividing ln(2) by the linear attenuation coefficient. The purpose of this study was to establish a direct computational model for determining HVL, a vital parameter in nuclear radiation safety studies and shielding material design. Accordingly, a typical gamma-ray transmission setup has been modeled using MCNPX (version 2.4.0) general-purpose Monte Carlo code. The MCNPX code's INPUT file was designed with two detection locations for primary and secondary gamma-rays, as well as attenuator material between those detectors. Next, Half Value Layer values of some well-known gamma-ray shielding materials such as lead and ordinary concrete have been calculated throughout a broad gamma-ray energy range. The outcomes were then compared to data from the National Institute of Standards and Technology. The Half Value Layer values obtained from MCNPX were reported to be highly compatible with the HVL values obtained from the NIST standard database. Our results indicate that the developed INPUT file may be utilized for direct computations of Half Value Layer values for nuclear safety assessments as well as medical radiation applications. In conclusion, advanced simulation methods such as the Monte Carlo code are very powerful and useful instruments that should be considered for daily radiation safety measures. The modeled MCNPX input file will be provided to the scientific community upon reasonable request. © 2022 Korean Nuclear SocietyPrincess Nourah Bint Abdulrahman University, PNU: PNURSP2022R149This work was performed under Princess Nourah bint Abdulrahman University Researchers Supporting Project Number (PNURSP2022R149), Princess Nourah bunt Abdulrahman University, Riyadh, Saudi Arabia. The authors express their sincere gratitude to Princess Nourah bint Abdulrahman University

Amyloid Inspired Self-Assembled Peptide Nanofibers

Cataloged from PDF version of article.Amyloid peptides are important components in many degenerative diseases as well as in maintaining cellular metabolism. Their unique stable structure provides new insights in developing new materials. Designing bioinspired selfassembling peptides is essential to generate new forms of hierarchical nanostructures. Here we present oppositely charged amyloid inspired peptides (AIPs), which rapidly self-assemble into nanofibers at pH 7 upon mixing in water caused by noncovalent interactions. Mechanical properties of the gels formed by selfassembled AIP nanofibers were analyzed with oscillatory rheology. AIP gels exhibited strong mechanical characteristics superior to gels formed by self-assembly of previously reported synthetic short peptides. Rheological studies of gels composed of oppositely charged mixed AIP molecules (AIP-1 + 2) revealed superior mechanical stability compared to individual peptide networks (AIP-1 and AIP-2) formed by neutralization of net charges through pH change. Adhesion and elasticity properties of AIP mixed nanofibers and charge neutralized AIP-1, AIP-2 nanofibers were analyzed by high resolution force− distance mapping using atomic force microscopy (AFM). Nanomechanical characterization of self-assembled AIP-1 + 2, AIP-1, and AIP-2 nanofibers also confirmed macroscopic rheology results, and mechanical stability of AIP mixed nanofibers was higher compared to individual AIP-1 and AIP-2 nanofibers self-assembled at acidic and basic pH, respectively. Experimental results were supported with molecular dynamics simulations by considering potential noncovalent interactions between the amino acid residues and possible aggregate forms. In addition, HUVEC cells were cultured on AIP mixed nanofibers at pH 7 and biocompatibility and collagen mimetic scaffold properties of the nanofibrous system were observed. Encapsulation of a zwitterionic dye (rhodamine B) within AIP nanofiber network was accomplished at physiological conditions to demonstrate that this network can be utilized for inclusion of soluble factors as a scaffold for cell culture studies. Copyright © 2012 American Chemical Societ

A comprehensive study of the energy absorption and exposure buildup factors of different bricks for gamma-rays shielding

The present investigation has been performed on different bricks for the purpose of gamma-ray shielding. The values of the mass attenuation coefficient (µ/ρ), energy absorption buildup factor (EABF) and exposure buildup factor (EBF) were determined and utilized to assess the shielding effectiveness of the bricks under investigation. The mass attenuation coefficients of the selected bricks were calculated theoretically using WinXcom program and compared with MCNPX code. Good agreement between WinXcom and MCNPX results was observed. Furthermore, the EABF and EBF have been discussed as functions of the incident photon energy and penetration depth. It has been found that the EABF and EBF values are very large in the intermediate energy region. The steel slag showed good shielding properties, consequently, this brick is eco-friendly and feasible compared with other types of bricks used for construction. The results in this work should be useful in the construction of effectual shielding against hazardous gamma-rays

Nitrogen source, an important determinant of fatty acid accumulation and profile in scenedesmus obliquus

The potential of algae-based fuel technologies for manufacturing renewable biofuels has been attracting interest from the scientific community. Biomass productivity and cellular lipid content are important parameters affecting the feasibility of using algae oil for biodiesel production. This study compares utilization of NaNO3, NH4Cland urea as different nitrogen sources in terms of their effects on biomass productivity, fatty acid profile and accumulation in Scenedesmus obliquus. Cellular lipid accumulation was analyzed by gravimetric, fluorometric, and flow-cytometric methods, besides collecting spectrophotometric data for biomass productivity analysis. In addition, fatty acid profiles were compared by using gas chromatography–mass spectrometry. The alga can utilize all tested nitrogen sources successfully however growth rates demonstrate differences. Gravimetric lipid content analysisshowed approximately a 1.5-fold increase in total lipid accumulation under NH4Cl regime when compared tothat of NaNO3 and a 2-fold increase when compared to that of urea at the end of ten days cultivation course. Fatty acid profiles under different nitrogen regimes present variations especially under NH4Cl regime. Moreover,all lipid extracts mostly consist of saturated, straight- and branched-chain hydrocarbons of different chain lengths ranging from C16–C20 which grant a suitable profile for biodiesel production. Scenedesmus obliquus is a suitable species for biodiesel production. The results obtained from this study provide a better understanding of cultivation characteristics of this important species and support potential, future biodiesel production

Encapsulation of a zinc phthalocyanine derivative in self-assembled peptide nanofibers

Cataloged from PDF version of article.In this article, we demonstrate encapsulation of octakis(hexylthio) zinc phthalocyanine molecules by non-covalent supramolecular organization within self-assembled peptide nanofibers. Peptide nanofibers containing octakis(hexylthio) zinc phthalocyanine molecules were obtained via a straight-forward one-step self-assembly process under aqueous conditions. Nanofiber formation results in the encapsulation and organization of the phthalocyanine molecules, promoting ultrafast intermolecular energy transfer. The morphological, mechanical, spectroscopic and non-linear optical properties of phthalocyanine containing peptide nanofibers were characterized by TEM, SEM, oscillatory rheology, UV-Vis, fluorescence, ultrafast pump-probe and circular dichroism spectroscopy techniques. The ultrafast pump-probe experiments of octakis(hexylthio) zinc phthalocyanine molecules indicated pH controlled non-linear optical characteristics of the encapsulated molecules within self-assembled peptide nanofibers. This method can provide a versatile approach for bottom-up fabrication of supramolecular organic electronic devices. © 2012 The Royal Society of Chemistry

Utilization of artificial intelligence approach for prediction of DLP values for abdominal CT scans: A high accuracy estimation for risk assessment

PurposeThis study aimed to evaluate Artificial Neural Network (ANN) modeling to estimate the significant dose length product (DLP) value during the abdominal CT examinations for quality assurance in a retrospective, cross-sectional study.MethodsThe structure of the ANN model was designed considering various input parameters, namely patient weight, patient size, body mass index, mean CTDI volume, scanning length, kVp, mAs, exposure time per rotation, and pitch factor. The aforementioned examination details of 551 abdominal CT scans were used as retrospective data. Different types of learning algorithms such as Levenberg-Marquardt, Bayesian and Scaled-Conjugate Gradient were checked in terms of the accuracy of the training data.ResultsThe R-value representing the correlation coefficient for the real system and system output is given as 0.925, 0.785, and 0.854 for the Levenberg-Marquardt, Bayesian, and Scaled-Conjugate Gradient algorithms, respectively. The findings showed that the Levenberg-Marquardt algorithm comprehensively detects DLP values for abdominal CT examinations. It can be a helpful approach to simplify CT quality assurance.ConclusionIt can be concluded that outcomes of this novel artificial intelligence method can be used for high accuracy DLP estimations before the abdominal CT examinations, where the radiation-related risk factors are high or risk evaluation of multiple CT scans is needed for patients in terms of ALARA. Likewise, it can be concluded that artificial learning methods are powerful tools and can be used for different types of radiation-related risk assessments for quality assurance in diagnostic radiology

Calculation of NaI(Tl) detector efficiency using 226Ra, 232Th, and 40K radioisotopes: Three-phase Monte Carlo simulation study

Thallium-activated sodium iodide (NaI(Tl)) detectors can be used in gamma cameras, environmental radiation assessments, including radiation emission levels from nuclear reactors, and radiation analysis equipment. This three-phase investigation aimed to model a standard NaI(Tl) detector using the Monte Carlo N-Particle eXtended (MCNPX) general-purpose Monte Carlo simulation techniques. Accordingly, a standard NaI(Tl) detector was designed along with the required properties. Next a validation study of the modelled NaI(Tl) detector has been performed based on the experimental results for absolute detector efficiency values obtained from 226Ra, 232Th, and 40K radioisotopes. Our findings indicate that the obtained absolute detector efficiency values are quite close to used experimental values. Finally, we used the modelled detector for determination of mass attenuation coefficients of Ordinary concrete, Lead, Hematite-serpentine concrete, and Steel-scrap concrete at 186.1, 295.22, 351.93, 609.31, 1120.29, 1764.49, 238.63, 911.2, 2614, and 1460.83 keV gamma-ray energies. Additionally, according to our findings, mass attenuation coefficients obtained from the newly designed detector are compatible with the standard NIST (XCOM) data. To conclude, continuous optimisation procedures are strongly suggested for sophisticated Monte Carlo simulations in order to maintain a high degree of simulation reliability. As a result, it can be concluded that the validation of the simulation model is necessary using measured data. Finally, it can also be concluded that the validated detector models are effective instruments for obtaining basic gamma-ray shielding parameters such as mass attenuation coefficients. © 2022 Huseyin Ozan Tekin et al., published by De Gruyter

The Impact of PbF2-Based Glasses on Radiation Shielding and Mechanical Concepts: An Extensive Theoretical and Monte Carlo Simulation Study

This work aimed to investigate the impact of Lead-fluoride based glasses via theoretical and simulation techniques on mechanical and radiation shielding parameters. Accordingly, Bi2O3 was blended with TeO2–B2O3–PbF2 glasses by using melt-quenching method. Using Fluka Monte Carlo code, the radiation shielding properties have measured. Moreover, Comparatively higher density PbF80 = 6.163 g/cm3 with 80 mol % Bi2O3, greater µ, µm and Zeff and lower T1/2, λ, tenth value layer values achieved for TeO2–B2O3– PbF2/Bi2O3 glass pointed it out as the best shield of gamma. Besides, the computed effective removal cross-sections against fast neutrons (ΣR) observed that the PbF80 sample has commensurately greater with a value 5.2954 (cm−1). The results observed that the variation PbF2/Bi2O3 improves the gamma protection ability of Lead-fluoride based glasses. The incremental of Bi2O3 at the expense of PbF2 increases the density and the packing density of the glasses and hence increase the longitudinal modulus-L, shear modulus-S, bulk modulus-K, and Young's modulus-Y from 15.89 to 25.9 GPa, from 8.49 to 12.09 -GPa, from 4.58 to 9.77 GPa, and from 15.74 to 25.69 GPa, respectively. The increase of the elastic moduli can be attrinuted to the glass former role of Bi2O3. The results indicate that the highest PbF2/Bi2O3 ratio encoded PbF00 has the best shielding and mechanical competence with measurable physical properties. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Taif University Researchers Supporting Project number (TURSP-2020/45) Taif University, Taif, Saudi Arabia

A Closer Look on Nuclear Radiation Shielding Properties of Eu3+ Doped Heavy Metal Oxide Glasses: Impact of Al2O3/PbO Substitution

In this study, a group of heavy metal oxide glasses with a nominal composition of 55B2 O3 + 19.5TeO2 + 10K2 O + (15−x) PbO + xAl2 O3 + 0.5Eu2 O3 (where x = 0, 2.5, 5, 7.5, 10, 12.5, and 15 in wt.%) were investigated in terms of their nuclear radiation shielding properties. These glasses containing lanthanide-doped heavy metal oxide were envisioned to yield valuable results in respect to radiation shielding, and thus a detailed investigation was carried out; the obtained results were compared with traditional and new generation shields. Advanced simulation and theoretical methods have been utilized in a wide range of energy regions. Our results showed that the AL0.0 sample with the highest PbO contribution had superior shielding properties in the entire energy range. The effective removal of cross-sections for fast neutrons (ΣR) was also examined. The results indicated that AL5.0 had the greatest value. While increasing the concentration of Al2 O3 in samples had a negative effect on the radiation shielding characteristics, it can be concluded that using PbO in the Eu3+ doped heavy metal oxide glasses could be a useful tool to keep gamma-ray shielding properties at a maximum level. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Acknowledgments: This research was funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Fast-track Research Funding Program