Search

3D printing is increasingly used in dentistry, with biocompatible resins playing a key role. This study compared the radioprotective properties of a commonly used 3D-printed resin (Formlabs surgical guide resin) with traditional heat-cured resin and examined the relationship between material thickness and radiation attenuation. The specimens consisted of 3D-printed and heat-cured resin specimens, each measuring 45 × 45 mm2, with five different thicknesses (6, 8, 10, 12, and 14 mm), totaling 100 samples. Both types of resin specimens underwent testing with 150 MU external beam radiation therapy (EBRT) and 400 cGy brachytherapy. Radiation experiments indicated that under EBRT conditions, there were no significant differences in radiation attenuation between the 3D-printed and heat-cured resins across all thickness groups. In brachytherapy, the attenuation of the 3D-printed resin was significantly lower than the heat-cured resin in the 6 mm and 8 mm groups. Specifically, attenuation rates were 48.0 ± 0.7 (3D-printed) vs. 45.2 ± 1.9 (heat-cured) in the 6 mm group, and 39.6 ± 1.3 vs. 37.5 ± 1.1 in the 8 mm group. Both resins showed significant positive linear correlations between thickness and attenuation (p < 0.001) within 6–14 mm. Thus, 3D-printed resin shows promising radioprotective properties and is a viable alternative to traditional heat-cured resin. [ABSTRACT FROM AUTHOR]

Based on the experimental and theoretical radiation attenuation, this study produced and tested a composite material made of polyester reinforced with SnO at varied concentrations and abbreviated as Pol-SnOx, where x = 0–60% with steps of 20 wt% Also, the polyester samples were doped with SnO of different particle sizes: Micro, Nano, and 50% Micro/50% Nano mix to investigate the effect of the particle size on the radiation attenuation performance. In the photon energy range of 0.015–15 MeV, their radiation shielding properties were empirically determined using an HPGe detector and theoretically determined using Phy-X/PSD software. The linear attenuation coefficient (LAC) values dropped from 1.361 to 0.022 cm−1 for Pol-SnO0, from 13.611 to 0.033 cm−1 for Pol-SnO20, from 31.700 to 0.049 cm−1 for Pol-SnO40, and from 61.076 to 0.076 cm−1 for Pol-SnO60 in the photon energy (Eγ) range from 0.015 to 15 MeV. The LAC values of the fabricated Pol-SnOx samples increased as the SnO concentrations increased. Also, the addition of 50% Micro/50% Nano mix particle size of the SnO to the polyester significantly increased the values of the LAC. The percentages of LAC improvement of SnO nano-particles were 16.625%, 13.236%, 8.714%, and 7.935% at the Eγ values of 0.059, 0.661, 1.173, and 1.332 MeV, respectively. Also, the LAC values were enhanced by adding SnO containing 50% Micro/50% Nano mix particles by 19.097%, 15.271%, 9.854%, and 9.071% at the Eγ values of 0.059, 0.661, 1.173, and 1.332 MeV, respectively, when compared to microparticles. The addition of 50% Micro/50% Nano Mix of SnO with 60% content to the polyester showed the highest LAC and radiation protection efficiency and lowest half-value layer and transmission factor among the other samples due to increased SnO doping and interparticle distances of the Micro and Nano mix.

The polymer/metal hybrids have been used as a solution for the mitigation of ionizing radiation in space for sensitive electronics components, particularly for a proton-rich Low Earth Orbit (LEO) environment. Consequently, radiation attenuation analysis of polymer/metal hybrid composites has been investigated. Radiation attenuation analysis has been performed using online GEANT4 (simulation toolkit) and the Multilayer Shielding Simulation System (MULASSIS) for the LEO space environment. The shielding potential of polymers, such as poly(dimethyl siloxane), poly(methyl methacrylate), polyurethane and ultra-high molecular weight polyethylene, were analyzed with optimized compositions. It was observed that the pristine PDMS attenuated relatively more radiations than other polymer matrices. For modelling of hybrid radiation material composition, PDMS and carbon fibre fabric-derived composite laminates along with metal sheets (Aluminum Al, Tantalum Ta or Tungsten W) were used to analyze hybrid compositions. Here, hybrid composition performance was analyzed as a function of various areal densities. Analyzed polymer laminate/metal hybrid compositions performed better to attenuate LEO radiations up to 42.29%, compared to conventional Al (areal densities of 0.2–1.0 g/cm2). The maximum magnitude of attenuation was found at an areal density of 1.0 g/cm2 for Ta and W metal composition (39.44% and 42.29%, respectively), and so performed better than Al metal. Improved attenuation ratios of the hybrid compositions revealed that the hybrid laminate/metal shields can replace conventional Al shields towards LEO space radiations. [ABSTRACT FROM AUTHOR]

Due to the country's rapidly expanding economy, Jordanian citizens are replacing their old homes with contemporary multistory structures. Because of the many benefits that come with glasses, these materials are employed for both structural and ornamental purposes. In this study, we investigate the ionising radiation protection and attenuation capabilities of commercial glasses. The shielding capabilities of three glass samples (JOR-1, JOR-2, and JOR-3) with varying elemental weight fractions were examined using a well-shielded NaI detector. We reported the fundamental attenuation coefficients for the glasses under investigation at photon energies of 0.662, 1.173, and 1.333 MeV. The chemical composition of these glasses was examined using Energy Dispersive X-ray (EDX) analysis. JOR-1 is mainly composed of O (40.88%) and Si (25.97%), with minor contributions from Na (7.59%), Mg (1.57%) and Ca (4.74%). JOR-2 contains Sn (2.37%) in addition to O (42.58%), Si (36.35%), Na (7.74%), and Mg (1.92%). JOR-3 has similar composition with JOR-2 and contains O (43.86%) and Si (36.90%), and notable amounts of Na (8.88%), Mg (1.81%), Ca (8.31%), and S (0.25%). We studied the effective atomic number (Zeff) for the commercial glasses and we found that the elevated amount of elements with higher atomic numbers, like Ca, Si and S, led to superior Zeff values for JOR-2 glass. The absence of Carbon in JOR-2 further improved its Zeff, with Tin's presence in JOR-2 slightly edging its Zeff over JOR-3. We compared the HVL for the current commercial glasses with other commercial glasses at 0.662 MeV. We found that JOR-1, JOR-2 and JOR-3 glasses provide better radiation attenuation than rider, PHP and Osmania glasses, while they have higher HVL than RS-360 and very close HVL with RS-253-G18. [ABSTRACT FROM AUTHOR]

3D printing is increasingly used in dentistry, with biocompatible resins playing a key role. This study compared the radioprotective properties of a commonly used 3D-printed resin (Formlabs surgical guide resin) with traditional heat-cured resin and examined the relationship between material thickness and radiation attenuation. The specimens consisted of 3D-printed and heat-cured resin specimens, each measuring 45 × 45 mm2, with five different thicknesses (6, 8, 10, 12, and 14 mm), totaling 100 samples. Both types of resin specimens underwent testing with 150 MU external beam radiation therapy (EBRT) and 400 cGy brachytherapy. Radiation experiments indicated that under EBRT conditions, there were no significant differences in radiation attenuation between the 3D-printed and heat-cured resins across all thickness groups. In brachytherapy, the attenuation of the 3D-printed resin was significantly lower than the heat-cured resin in the 6 mm and 8 mm groups. Specifically, attenuation rates were 48.0 ± 0.7 (3D-printed) vs. 45.2 ± 1.9 (heat-cured) in the 6 mm group, and 39.6 ± 1.3 vs. 37.5 ± 1.1 in the 8 mm group. Both resins showed significant positive linear correlations between thickness and attenuation (p < 0.001) within 6–14 mm. Thus, 3D-printed resin shows promising radioprotective properties and is a viable alternative to traditional heat-cured resin.

This study explores the radiation shielding properties of an xGd2O3 – (60-x)ZnO–15B2O3–5Al2O3–20SiO2 glass system (x = 0—3 mol %) glass system using FLUKA and XCOM software. The glass system is interesting due to its potential applications in nuclear and medical settings, where effective radiation-shielding materials are crucial. The FLUKA Monte Carlo simulation package is utilized to model the interaction of gamma photons with the glass system. At the same time, the XCOM software calculates the macroscopic cross-sections based on their elemental composition. The investigation evaluates parameters such as attenuation coefficients, dose rates, neutron cross-section, and stopping power for different radiation sources and energies. Various configurations are analyzed by varying the Gd2O3 concentrations in the present glass system to optimize shielding effectiveness. The results refer to the high radiation shielding potential of gamma rays and neutrons for the present glassy materials compared to previously studied shielding materials. The present study offers valuable insights into the radiation shielding properties of the studied glass system, facilitating the design and development of efficient radiation shielding materials for practical implementation in nuclear and medical industries. [ABSTRACT FROM AUTHOR]

The role of the addition of rare-earth ions which are Pr2O3, N2O3, Sm2O3, and Eu2O3 to Li2O–ZnO–B2O3 glasses on the optical and radiation attenuation characteristics was theoretically investigated. According to the addition of the rare-earth ions, the glasses were named as LZB, LZBPr, LZBNd, LZBSm and LZBEu. The LZB glass has the greatest molar refractivity and the molar polarizability whereas LZBPr glass has the lowest molar refractivity and the molar polarizability. The reflection loss is the highest for the LZB and the optical transmission is the highest for LZBEu. Especially, at higher gamma-ray energy (5–15 MeV), the linear attenuation coefficients are the greatest for LZBPr and they are the lowest for LZB. The LZBPr has the lowest half value layer, tenth value layer and mean free path at 10 MeV gamma-ray energy. At higher gamma-ray energies, LZBPr has the better radiation protection efficiency. Consequently, the LZBPr glass has the superior radiation attenuation ability and the addition of rare-earth ions to LZB glass enhances radiation shielding ability of the studied glasses.

After many decades of research, a schistosome vaccine still looks to be a distant prospect. These helminths can live in the human bloodstream for years, even decades, surrounded by and feeding on the components of the immune response they provoke. The original idea of a vaccine based on the killing of invading cercariae in the skin has proven to be illusory. There has also been a realisation that even if humans develop some protection against infection over a protracted period, it very likely involves IgE-mediated responses that cannot provide the basis for a vaccine. However, it has also become clear that both invasive migrating larvae and adult worms must expose proteins and release secretions into the host environment as part of their normal biological activities. The application of modern 'omics approaches means that we now have a much better idea of the identity of these potential immune targets. This review looks at three animal models in which acquired immunity has been demonstrated and asks whether the mechanisms might inform our vaccine strategies to achieve protection in model hosts and humans. Eliciting responses, either humoral or cellular, that can persist for many months is a challenge. Arming of the lungs with effector T cells, as occurs in mice exposed to the radiation-attenuated cercarial vaccine, is one avenue. Generating IgG antibody titres that reach levels at which they can exert sustained immune pressure to cause worm elimination, as occurs in rhesus macaques, is another. The induction of memory cell populations that can detect trickle invasions of larval stages remains to be explored. One promising approach is the analysis of protective antibodies using high-density peptide arrays of target proteins to identify reactive regions. These can be combined in multi-epitope constructs to immunise a host against many targets simultaneously and cheaply. [ABSTRACT FROM AUTHOR]

The effects of radiation have been detrimental to human health, electronics, and environment, as the incremental application of radioactively affiliated substrates has escalated radioactive hazards thereby increasing the quests for the construction of engineered materials capable of mitigating the adverse effects of radiation hazards. In recent decades, due to the advent of nanotechnology, polymeric nanocomposites reinforced with a versatile range of nanoparticulates have demonstrated high prospects for radiation attenuation attributable to their inherently enhanced radiation attenuation properties. Hence, this paper presents recently emerging progresses in the construction of polymeric materials and nanocomposites for attenuating radiation hazards. [ABSTRACT FROM AUTHOR]

This study aimed to prepare silicone rubber composites with heavy metal oxide nanoparticles for gamma ray shielding applications. Different heavy metal oxide nanoparticles were incorporated into the silicone rubber matrix, and the prepared composites were characterized for their thermal, mechanical, and radiation shielding properties. The density of the prepared SR samples ranged from 1.25 to 2.611 g·cm−3, with SR-2 having the highest density due to the presence of lead oxide. Additionally, the thermal stability of the materials improved with the addition of HMO nanoparticles, as indicated by TGA results. The prepared SR materials showed ultimate deformation displacement ranging from 14.17 to 21.23 mm, with the highest value recorded for SR-3 and the lowest for SR-2. We investigated the transmission factor (TF) of gamma rays through silicone rubber (SR) composites with different heavy metal oxide (HMO) nanoparticles. The addition of HMOs resulted in a decrease in TF values, indicating improved radiation shielding performance. The TF was found to be lowest in SR-5, which contained 15% of Bi2O3, WO3, BaO, and Zr2O3 each. The linear attenuation coefficient (LAC) of the SR samples was also evaluated, and it was found that the incorporation of HMOs increased the probability of photon interactions, leading to improved radiation protection effectiveness. The half-value layer (HVL) of the SR samples was also examined, and it was found that the addition of HMOs resulted in a significant reduction in HVL values, particularly at low energy levels. SR-5 had the lowest HVL among the group, while SR-2, SR-3, and SR-4 had higher HVL values. These results demonstrate the effectiveness of using HMOs in enhancing the radiation shielding properties of SR composites, particularly for low-energy gamma rays. [ABSTRACT FROM AUTHOR]

To develop and validate a simple approach for building cost-effective imaging phantoms for Cone Beam Computed Tomography (CBCT) using a modified Polyjet additive manufacturing technology where a single material can mimic a range of human soft-tissue radiation attenuation. Single material test phantoms using a cubic lattice were designed in 3-Matic 15.0 software. Keeping the individual cubic lattice volume constant, eight different percentage ratio (R) of air: material from 0% to 70% with a 10% increment were assigned to each sample. The phantoms were printed in three materials, namely Vero PureWhite, VeroClear and TangoPlus using Polyjet technology. The CT value analysis, non-contact profile measurement and microCT-based volumetric analysis was performed for all the samples. The printed test phantoms produced a grey value spectrum equivalent to the radiation attenuation of human soft tissues in the range of −757 to +286 HU on CT. The results from dimensional comparison analysis of the printed phantoms with the digital test phantoms using non-contact profile measurement showed a mean accuracy of 99.07 % and that of micro-CT volumetric analysis showed mean volumetric accuracy of 84.80–94.91%. The material and printing costs of developing 24 test phantoms was 83.00 Euro. The study shows that additive manufacturing-guided macrostructure manipulation modifies successfully the radiographic visibility of a material in CBCT imaging with 1 mm3 resolution, helping customization of imaging phantoms. [ABSTRACT FROM AUTHOR]

Airborne hyperspectral imaging plays an increasingly important role in environmental monitoring. However, due to the limitations of the acquisition conditions, there are uneven radiation and chromatic aberrations in the mosaic data. Accurate preprocessing of the original data is the premise of qualitative and quantitative remote sensing. In this study, we proposed a comprehensive radiation distortion correction method that integrates radiation attenuation difference correction, topographic correction, and multi-strip images consistency adjustment (RA-TOC-CA). First, the radiation attenuation equation was constructed by combining the viewing geometry, terrain, and the elevation difference between the UAV and the ground to eliminate the radiation attenuation difference of pixels acquired at the different instantaneous field of view (IFOV). Second, an improved kernel-driven BRDF model was built combining terrain information and illumination-viewing (flight attitude and sensor IFOV) geometry to eliminate the radiation unevenness and BRDF distortion caused by topography. Third, adjusting the reflectance of multi-strip images according to the homonymous points' reflectance of adjacent strips should be equal, eliminating the radiation differences between multiple strips. Based on multi-strip airborne hyperspectral images collected in the Shaanxi province of China, the correction results of the RA-TOC-CA method were compared with those of the SCS+C and Minnaert+SCS methods regarding various evaluation criteria. The results showed that SCS+C and Minnaert+SCS can reduce the topographic effect but cannot eliminate the reflectance difference at the edges of adjacent images, and SCS+C overcorrects the reflectance. RA-TOC-CA weakened the topographic effects and brightness gradient, which was physically stable and generalizable. Compared with previous studies, RA-TOC-CA provided a complete radiation distortion correction method for airborne hyperspectral images and had a solid theoretical basis. This study introduces an effective method for radiation distortion correction of airborne hyperspectral images and provides technical support for large-scale applications of hyperspectral images. [ABSTRACT FROM AUTHOR]

It can be considered that electric generating power from solar energy is an essential topic in the energy field. Several environmental factors affect the energy production of solar cells. Dust accumulation is one of the main factors which significantly negatively influences output energy. However, this topic is not investigated extensively, despite its significant impact, especially in arid areas such as Iraq. In this research paper, both theoretical and experimental techniques were applied to investigate the effect of accumulated dust particles on the efficiency of photovoltaic PV systems. An on-grid photovoltaic system was selected to achieve the experimental work. The results proved the negative effect of dust particles on the performance of the solar cell. Based on the obtained results, a new relationship was introduced between efficiency degradation and the amount of dust that accumulated on the surfaces of cells. This correlation is considered a necessity to find the characteristics of PV solar systems to improve their performance and efficiency. The new correlation introduced in this paper can be considered a promising prediction tool to estimate the characteristics of photovoltaic solar cells under different actual environment working conditions. The output power of the cleaned array system increased by 5-26% compared with the untreated system over the test period. Furthermore, the performance ratio (PR) was enhanced within the cleaned array system by 3 to 6 compared with the uncleaned array. A significant formula introduced the connection between the actual output power of the PV systems and the environmental condition (dust accumulation), where it can be considered as feedback to keep the performance in a steady status, which means obtaining the highest output power. [ABSTRACT FROM AUTHOR]

Barite and hematite are the most common heavy-weight minerals applied as aggregates in radiation shielding concrete (RSC). Therefore, to limit the cement consumption and reduce the CO2 emissions accompanying its production, the aim of this study is to use Egyptian barite and hematite minerals in their native status and evaluate their attenuation efficiency against fast neutrons and γ-rays. This was implemented through the measurement of their radiation attenuation against fast neutrons and γ-rays in the energy ranges of 0.80–11 and 0.40–8.30 MeV, respectively, employing a Pu-Be source and a stilbene scintillator. Theoretical calculations were prepared using the NXcom program to validate the fast neutron attenuation measurements. Furthermore, the implications of the physical, mineralogical, geochemical, and morphological characteristics of these heavy-weight minerals with respect to their attenuation efficiencies were considered. We found that barite has superior radiation attenuation efficiency for fast neutrons and γ-rays compared to hematite by 9.17 and 51% for fast neutrons and γ-rays, respectively. This was ascribed to the superior physical, mineralogical, geochemical, and morphological properties of the former relative to those of the latter. Furthermore, a satisfactory agreement between the experimental and theoretical results was achieved, with a deviation of 16 and 19.25% for the barite and hematite samples, respectively. Eventually, barite and hematite can be successful candidates for their use as sustainable alternatives to common RSC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different samples consisting of lead-free cuprate added with MnFe 2 O 4 were prepared. • XRD showed that the samples are polycrystals with an orthorhombic structure. • Gamma radiation shielding properties were evaluated using Monte Carlo Simulation. • The MnFe 2 O contents have an impact on the gamma radiation shielding properties. • The prepared samples are suitable for shielding the low- and mid-energetic γ-ray photons. In this work, efficient lead-free cuprate-based shielding materials mixed with different ratios (x = 0.1–2 wt%) of magnetic MnFe 2 O 4 powder against nuclear radiation were proposed. The samples were prepared by using a mixture of raw materials of oxides for the preparation of the host cuprate Y 1 Ba 2 Cu 3 O y materials and a mixture of nitrates in the presence of solvent for the formation of magnetic MnFe 2 O 4 powder additive. The phase, crystalline structure, and composition were examined by X-ray diffraction. The main Y 1 Ba 2 Cu 3 O y phase revealed good crystallinity and orthorhombic structure. As the ratio of magnetic MnFe 2 O 4 powder additive increases, the orthorhombicity decreases. Gamma shielding performance was analyzed by using MNCP5 code. The analyses indicate that the addition of magnetic powder has an influence on the shielding performance of cuprate-class material. The radiation shielding performance of prepared materials is nearly the same with the low ratios of MnFe 2 O 4 (i.e. x = 0.1 and 0.5 wt%). Yet, with further increasing the amount of MnFe 2 O 4 beyond x = 0.5 wt%, a considerable detraction of shielding parameters was noticed, as estimated by the Monte Carlo simulation (MCNP-5 code). The linear attenuation coefficient of cuprate-class materials decreased by 19.6 %, 33.6 %, 19.3 %, and 19.7 %, respectively at 0.015 MeV, 0.1 MeV, 0.662 MeV, and 15 MeV when the MnFe 2 O 4 concentration increased between 0.1 and 2 wt%. [ABSTRACT FROM AUTHOR]

In the present study, ferro manganese (HC), ferro chromium (MC), ferro silicon zirconium (FeSiZr), ferro silicon manganese (FeSiMn) and ferro silicon (FeSi 65%) ferroalloys have been investigated for nuclear radiation attenuation properties. For this aim, linear attenuation coefficients (LAC) were measured using Lambert-Beer law for transmission of the gamma rays at 81, 356, 661, 1173 and 1332 keV photon energies emitted from 133Ba, 137Cs and 60Co radioactive sources to irradiate the ferroalloys. The mass attenuation coefficient (MAC), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP) of ferroalloys were then determined using LACs in the same photon energies. Effective atomic numbers (Z eff) of ferroalloys were also obtained using total atomic cross-sections (σ a) calculated from MACs in the same photon energies. HC ferroalloy was found the best radiation shielding material due to the lower MFP and higher MAC values at the interested gamma ray energies at transmission geometry. The ferroalloys were also compared with some standard radiation shielding concretes. It was concluded that the ferroalloys showed better radiation shielding characteristics on behalf of MFP values at 356 keV photon energy. The studied ferroalloys have better MFPs between 2.91% (for FeSi 65%) and 66.81% (for HC) differences than standard concretes. [ABSTRACT FROM AUTHOR]

After many decades of research, a schistosome vaccine still looks to be a distant prospect. These helminths can live in the human bloodstream for years, even decades, surrounded by and feeding on the components of the immune response they provoke. The original idea of a vaccine based on the killing of invading cercariae in the skin has proven to be illusory. There has also been a realisation that even if humans develop some protection against infection over a protracted period, it very likely involves IgE-mediated responses that cannot provide the basis for a vaccine. However, it has also become clear that both invasive migrating larvae and adult worms must expose proteins and release secretions into the host environment as part of their normal biological activities. The application of modern ‘omics approaches means that we now have a much better idea of the identity of these potential immune targets. This review looks at three animal models in which acquired immunity has been demonstrated and asks whether the mechanisms might inform our vaccine strategies to achieve protection in model hosts and humans. Eliciting responses, either humoral or cellular, that can persist for many months is a challenge. Arming of the lungs with effector T cells, as occurs in mice exposed to the radiation-attenuated cercarial vaccine, is one avenue. Generating IgG antibody titres that reach levels at which they can exert sustained immune pressure to cause worm elimination, as occurs in rhesus macaques, is another. The induction of memory cell populations that can detect trickle invasions of larval stages remains to be explored. One promising approach is the analysis of protective antibodies using high-density peptide arrays of target proteins to identify reactive regions. These can be combined in multi-epitope constructs to immunise a host against many targets simultaneously and cheaply.

Radiation induces deterioration to life, the environment and electronic gadgets. Also, the escalating quests in use of radioactive entities has induced increased radioactive hazards resulting in the need to fabricate advanced materials for efficient protection against the deteriorating effects of radiation. Inclusive of differing techniques to achieve radiation attenuation, the use of compounds exhibiting elevated atomic number (Z), including lead, has been attained. On the other hand, lead exhibit toxicity. Therefore, varying researches have investigated the use of minimally-toxic post-transitionally metallic-oriented compounds, such as bismuth. However, polymeric materials offer great prospects attributable to their inherent electrical, mechanical, thermal, as well as multi-functional dispositions. However, composites fabricated from polymers with elevated atomic number reinforcements facilitate attainment of materials exhibiting minimal weight, good flexibility, and exceptional processability. Therefore, this paper elucidates emerging advancements in synthesization of polymeric materials and nanoarchitectures for radiation protection, focusing on application of polymeric nanoarchitectures for attenuation of varying forms of radiation. [ABSTRACT FROM AUTHOR]

In the present work, an experimental study is performed to study the radiation shielding characteristics of SrTiO3 (STO) perovskite ceramic added with different amounts (x = 0, 2, 5, and 10%) of tungsten trioxide nanoparticles (WO3 NPs). The four ceramic samples were prepared using the solid-state reaction method. The structural properties were examined using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The analysis showed the successful formation of WO3- doped STO samples. The crystallite size, estimated using the Scherrer equation, was found in the range of 50.86–41.17 nm. The effect of WO3 NPs on the radiation shielding performance of these ceramics was studied. Different parameters, such as linear attenuation coefficient (LAC) and other related factors, were experimentally determined. The linear attenuation coefficient results demonstrated that the additional amount of WO3 in the ceramics correlates with an improvement in their shielding abilities. The half-value layer (HVL) values for the ceramics with 2% WO3 nanoparticles are equal to 0.071, 1.760, 2.407, and 2.564 cm at 0.060, 0.662, 1.173, and 1.333 MeV, respectively. As the energy increases, more radiation can pass through the material; therefore, a larger thickness is required to absorb half of the total photons, leading to a greater HVL. The tenth value results reaffirmed that increasing the WO3 content in the STO ceramics improves their shielding efficiency. The radiation protection efficiency (RPE) of the four prepared STO ceramics was reported. From the RPE, we found that more photons can be attenuated at lower energies. [ABSTRACT FROM AUTHOR]

A group of novel CeO 2 thin films were synthesised using ultrasonic spray pyrolysis process. The composition ratios of these films were modified to investigate changes in their optical, surface, electrical, and structural characteristics. Absorbance spectra in the range 300–900 nm was acquired. Transmittance in the visible area was determined to be 50%. The optical band gap was reported to vary between 3.38 and 3.52eV using absorbance spectra. X-ray diffraction was used to analyse the films' structure, while atomic force microscopy was used to determine the surface roughness values. Spectroscopic ellipsometry and the Cauchy–Urbach model were used to calculate the thicknesses. Electrical resistivity values were determined using a four-probe system. CeO 2 thin film X-ray diffraction patterns validated the polycrystalline cubic fluorite structure. According to the data, the deposited films expand preferentially in the (2 0 0) direction. The films were found to have a high resistivity of 106 Ω cm. We also evaluated the nuclear radiation shielding properties of CeO 2 thin films in the 0.015–15 MeV photon energy range. The results indicated that CeO 2 thin film exhibits promising half value layers of 0.00169 cm, 0.14055 cm, 1.62665 cm, and 2.30273 cm, respectively, for 0.015 MeV, 0.15 MeV, 1 MeV, and 15 MeV CeO 2 films have been determined to be worth working on and may be promising materials for optoelectronic and nuclear security applications. [ABSTRACT FROM AUTHOR]

Purpose: There is a lack of prospective studies evaluating the effects of body composition on postoperative complications after gastrectomy in a Western population with predominantly advanced gastric cancer.Methods: This is a prospective side study of the LOGICA trial, a multicenter randomized trial on laparoscopic versus open gastrectomy for gastric cancer. Trial patients who received preoperative chemotherapy followed by gastrectomy with an available preoperative restaging abdominal computed tomography (CT) scan were included. The CT scan was used to calculate the mass (M) and radiation attenuation (RA) of skeletal muscle (SM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT). These variables were expressed as Z-scores, depicting how many standard deviations each patient's CT value differs from the sex-specific study sample mean. Primary outcome was the association of each Z-score with the occurrence of a major postoperative complication (Clavien-Dindo grade ≥ 3b).Results: From 2015 to 2018, a total of 112 patients were included. A major postoperative complication occurred in 9 patients (8%). A high SM-M Z-score was associated with a lower risk of major postoperative complications (RR 0.47, 95% CI 0.28-0.78, p = 0.004). Furthermore, high VAT-RA Z-scores and SAT-RA Z-scores were associated with a higher risk of major postoperative complications (RR 2.82, 95% CI 1.52-5.23, p = 0.001 and RR 1.95, 95% CI 1.14-3.34, p = 0.015, respectively). VAT-M, SAT-M, and SM-RA Z-scores showed no significant associations.Conclusion: Preoperative low skeletal muscle mass and high visceral and subcutaneous adipose tissue radiation attenuation (indicating fat depleted of triglycerides) were associated with a higher risk of developing a major postoperative complication in patients treated with preoperative chemotherapy followed by gastrectomy. [ABSTRACT FROM AUTHOR]

In this study, a promising relationship between antibacterial zone and radiation attenuation properties was investigated in Ag2O doped bioactive glasses with a chemical composition of xAg2O–20Li2O–25TeO2-(55-x)B2O3 (where x = 0, 0.5, 1.0, 1.5, and 2.0 mol%). For this aim, a wide-ranging radiation attenuation characterization procedure was performed on Ag2O substituted bioactive glasses. The general-purpose Monte Carlo code MCNPX (v.2.7.0) was used to model bioactive glasses. The mass attenuation coefficients were calculated using a gamma-ray transmission setup. The coefficients obtained were used to determine other important attenuation properties. Finally, for particular behaviors, exposure (EBF) and energy absorption (EABF) build-up factors were calculated for specific attitudes of Ag2O substitutions in bioactive glasses during the interaction process. The results showed that there is direct relationship between Ag2O substitution amount and radiation attenuation properties. In addition to its well-behaviors on inhibition zone against bacterial occurrences, it can be concluded that increasing Ag2O would increase the gamma-ray attenuation properties of studied bioactive glass system.

In this study, the effects of replacing fine aggregate by granulated lead/zinc slag waste (GLZSW) on the thickness of concrete shields against X-ray radiation and on the compressive strength of concrete have been investigated. The fine aggregate was substituted by GLZSW in four percentages: 25%, 50%, 75%, and 100% (by weight). The first aim of the present study was to compare the thicknesses of concretes with GLZSW and control concrete using Lead Equivalent (LE). The second aim was to assess the effects of replacing fine aggregate by GLZSW on the compressive strength of concrete. Results of this study indicated that the compressive strength of mixed concretes increased significantly compared to the control upon replacing fine aggregate by GLZSW; the mixture containing 100% GLZSW had the greatest compressive strength. Further, the inclusion of GLZSW as a substitute for fine aggregate increased the radiation attenuation properties and consequently decreased the thickness of concrete shields in direct proportion to the mixing ratio of GLZSW. The results revealed that concrete mixes containing 100% GLZSW offered the greatest reduction in shield thickness. The study shows that there is a promising future for the use of GLZSW as substitute for fine aggregate in concrete used to shield against X-ray radiation.

This study aimed to prepare silicone rubber composites with heavy metal oxide nanoparticles for gamma ray shielding applications. Different heavy metal oxide nanoparticles were incorporated into the silicone rubber matrix, and the prepared composites were characterized for their thermal, mechanical, and radiation shielding properties. The density of the prepared SR samples ranged from 1.25 to 2.611 g·cm−3, with SR-2 having the highest density due to the presence of lead oxide. Additionally, the thermal stability of the materials improved with the addition of HMO nanoparticles, as indicated by TGA results. The prepared SR materials showed ultimate deformation displacement ranging from 14.17 to 21.23 mm, with the highest value recorded for SR-3 and the lowest for SR-2. We investigated the transmission factor (TF) of gamma rays through silicone rubber (SR) composites with different heavy metal oxide (HMO) nanoparticles. The addition of HMOs resulted in a decrease in TF values, indicating improved radiation shielding performance. The TF was found to be lowest in SR-5, which contained 15% of Bi2O3, WO3, BaO, and Zr2O3 each. The linear attenuation coefficient (LAC) of the SR samples was also evaluated, and it was found that the incorporation of HMOs increased the probability of photon interactions, leading to improved radiation protection effectiveness. The half-value layer (HVL) of the SR samples was also examined, and it was found that the addition of HMOs resulted in a significant reduction in HVL values, particularly at low energy levels. SR-5 had the lowest HVL among the group, while SR-2, SR-3, and SR-4 had higher HVL values. These results demonstrate the effectiveness of using HMOs in enhancing the radiation shielding properties of SR composites, particularly for low-energy gamma rays.

Airborne hyperspectral imaging plays an increasingly important role in environmental monitoring. However, due to the limitations of the acquisition conditions, there are uneven radiation and chromatic aberrations in the mosaic data. Accurate preprocessing of the original data is the premise of qualitative and quantitative remote sensing. In this study, we proposed a comprehensive radiation distortion correction method that integrates radiation attenuation difference correction, topographic correction, and multi-strip images consistency adjustment (RA-TOC-CA). First, the radiation attenuation equation was constructed by combining the viewing geometry, terrain, and the elevation difference between the UAV and the ground to eliminate the radiation attenuation difference of pixels acquired at the different instantaneous field of view (IFOV). Second, an improved kernel-driven BRDF model was built combining terrain information and illumination-viewing (flight attitude and sensor IFOV) geometry to eliminate the radiation unevenness and BRDF distortion caused by topography. Third, adjusting the reflectance of multi-strip images according to the homonymous points’ reflectance of adjacent strips should be equal, eliminating the radiation differences between multiple strips. Based on multi-strip airborne hyperspectral images collected in the Shaanxi province of China, the correction results of the RA-TOC-CA method were compared with those of the SCS+C and Minnaert+SCS methods regarding various evaluation criteria. The results showed that SCS+C and Minnaert+SCS can reduce the topographic effect but cannot eliminate the reflectance difference at the edges of adjacent images, and SCS+C overcorrects the reflectance. RA-TOC-CA weakened the topographic effects and brightness gradient, which was physically stable and generalizable. Compared with previous studies, RA-TOC-CA provided a complete radiation distortion correction method for airborne hyperspectral images and had a solid theoretical basis. This study introduces an effective method for radiation distortion correction of airborne hyperspectral images and provides technical support for large-scale applications of hyperspectral images.

Myosteatosis (pathological fat accumulation in muscle) is defined by lower mean skeletal muscle radiodensity in CT. We aimed to determine the optimal cut-offs for myosteatosis in a cohort of 855 patients with cirrhosis. CT images were used to determine the skeletal muscle radiodensity expressed as Hounsfield Unit (HU). Patients with muscle radiodensity values below the lowest tertile were considered to have myosteatosis. Competing-risk analysis was performed to determine associations between muscle radiodensity and pre-transplant mortality. Muscle radiodensity less than 33 and 28 HU in males and females, respectively, were used as cut-offs to identify myosteatosis. In the univariate analysis, cirrhosis etiology, MELD score, refractory ascites, variceal bleeding, hepatic encephalopathy, sarcopenia and myosteatosis were predictors of mortality. Myosteatosis association with mortality remained significant after adjusting for confounding factors (sHR 1.47, 95% CI 1.17–1.84, p = 0.001). Patients with concurrent presence of myosteatosis and sarcopenia constituted 17% of the patient population. The cumulative incidence of mortality was the highest in patients with concomitant sarcopenia and myosteatosis (sHR 2.22, 95% CI 1.64–3.00, p < 0.001). In conclusion, myosteatosis is common in patients with cirrhosis and is associated with increased mortality. The concomitant presence of myosteatosis and sarcopenia is associated with worse outcomes. [ABSTRACT FROM AUTHOR]

High-power microwave electrovacuum devices require bulk absorbers with a high absorption rate of microwave radiation. The absorption of microwave radiation by AlN–SiC composites is studied for their possible application, and it is found that high absorption rates can be achieved in the AlN–50 wt % SiC composite owing to the presence of micrometer and submicrometer SiC particles that provide complex and repeated absorption of microwave radiation. Absorption rate L is 4.6 dB/mm for disks with dimesions of ∅4.2 × 1.0 mm and 6.6 dB/mm for rings with sizes of ∅4.2 (external) × ∅1.9 (internal) × 1.0 mm. It is proposed to compare dielectric losses of the composites through the directly measured absorption rate of microwave radiation in real operating conditions of the bulk absorber in the microwave device, rather than through the value of dielectric losses ɛ'' or tan δ. The relationship between the quality factor, attenuation, and absorption of radiation is determined. It is shown that ɛ' and ɛ'' are frequency-dependent values in the frequency range of 1–40 GHz, but their ratio ɛ''/ɛ' = tan δ is a constant frequency-independent value at frequencies greater than 8 GHz. In the studied composite, the measured values of the real and imaginary parts of the complex permittivity are ɛ' = 32 and ɛ'' = 7 at a frequency of 3.3 GHz, and the calculated values are ɛ' = 19.3 and ɛ'' = 6.2 at a frequency of 34 GHz. [ABSTRACT FROM AUTHOR]

Chest X-ray is the first imaging procedure that play an important role in identification of COVID-19 as well as medical diagnostic and treatment of COVID-19 patients, in order to increase recovery rates and to lower fatality rates. Regardless of their environmental disadvantages and high toxicity, lead aprons are important materials for personal protection of physicians and patients from X-ray radiation during medical operations. Typically, for standard lead protective aprons, the transmittance values for lite-lead (LL) and regular lead (RL) were approximately 18 % and 17 %, respectively. With an aim to find new materials possibly to replace toxic lead-shielding products, in this study, an environmentally friendly and flexible fabric-based radiation shielding material was manufactured. Polyester fabric was coated by Bi2O3 nano particles using a simple, scalable, and cost-effective method to deposit the nanoparticles onto the textile fabric surface. This application method allows the potential production of nano-Bi2O3 coated polyester fabric at the maximum %uptake of 45 and mass per unit area of 0.41 g/cm² for 1 layer fabric. Radiation attenuation of the fabric increased with the numbers of fabric layers. Five layers of the fabric showed X-ray transmission of approximately 85% when measured at 80 kVp tube voltage, the medical application standard. To increase X-ray protection ability, the nano-Bi2O3 coated polyester fabric surface was recoated with PVA/ Bi2O3 coating composites using K-hand coater. The potential application of the recoated fabric as environmentally friendly and flexible fabric-based radiation shielding material for X-ray attenuation was also demonstrated. The 5-layer PLA/nano-Bi2O3 coated fabric showed the lowest X-ray transmission of 65.7%, implying the moderate improvement of shielding ability. This could lead to an X-ray protection textile garment that can potentially replace lead aprons. [ABSTRACT FROM AUTHOR]

The chemical and physical characteristics of several flavonoid compounds such as geraniol, thymoquinone, betaine, apigenin, N-acetylcysteine, catechin, l-carnosine, epigallocatachin, and saponarin were examined in this work. Numerous molecular properties of all flavonoid compounds used in this study were calculated using the Calculate Molecular Properties module of Accelrys Discovery Studio v20.1.0.19295.0. These properties included molecular polar surface area, total solvent accessible surface area, and heat of formation. We used the MCNPX general-purpose Monte Carlo code in combination with the Phy-X PSD software to determine gamma-ray interaction parameters such as attenuation coefficients, effective atomic numbers, and buildup factors. The findings indicate that the flavonoids’ elemental compositions have a direct effect on their chemical and physical properties. Additionally, a synergistic interaction of chemical and physical behaviors has been observed. Among the flavonoids studied, saporanin was shown to have the highest polar surface area and solvent accessible surface area, as well as the highest stability. Additionally, saporanin had the strongest gamma-ray attenuation characteristics across a broad photon energy range. It may be inferred that saporanin’s elemental structure enables a synergistic relationship between its chemical and physical characteristics. The findings of this study may contribute to the evaluation of saporanin’s hypoglycemic, antibacterial, and hepatoprotective effects.

Radiation attenuation and mechanical properties are two key parameters for shielding in space. This study explored the attenuation parameters of cadmium as a popular filler for the shielding of thermal neutrons in the unsaturated polyester (UPS) polymer matrix. The polyester matrix was used for the first time. The composite behavior against gamma radiation (by applying Cs-137 radioisotope, E gamma = 0.662 MeV) was evaluated using the gamma spectrometer. Also, the sample was exposed to neutron radiation by utilizing a239Pu–Be neutron source. The effect of the composite sample produced with the cadmium filler was also examined when exposed to gamma radiation. Further, the attenuation parameters of the gamma rays were studied. The observations indicated the suitable shielding of this composite for thermal neutrons, such that the half-value layer (HVL) decreased from 7.8 cm in the polyester sample to 0.22 cm in the polyester/10 wt% CdO composite sample. The linear attenuation coefficient of the thermal neutron increased from 0.0888 (cm-1) in the polyester sample to 3.15 (cm-1) in the 10 wt% CdO composite sample, thus indicating more than 35-fold improvement in the neutron attenuation. Composite samples were exposed to gamma radiation; contrary to the expectations, the results showed an almost twofold improvement in the attenuation of gamma radiation, as compared to the polyester sample. This composite specimen was coupled to a 2 mm thick linear low-density polyethylene (LLDPE) layer for the better shielding of thermal neutrons. Finally, the composite sample was mechanically reinforced with a silica glass fiber, which enhanced the ultimate tensile strength (UTS) from 39 to 298 MPa. Also, the elongation rate (% E) was raised from 6% in the polyester sample to 10.5% in the polyester/10 wt% CdO- silica glass fiber sample. Thus, the results indicated the production of a strong composite capable of attenuating neutron and gamma radiation. Accordingly, this composite could be considered a reliable option for use as a shield in space missions. At present, marine tools and equipment such as vessels as well as some compounds used in the defense and aerospace industries apply these composites. In the present study, to achieve high and reliable mechanical properties, UPS thermoset resins were employed and different adsorbent particles were investigated. Finally, the most optimal conditions in terms of percentage and type of adsorbent materials were determined. Then, the resin was added which continued with reinforcement by silicon fabric to develop a shield with suitable attenuation properties for a wide range of radiations. Finally, high mechanical properties, as well as high thermal and chemical stability, were achieved; accordingly, this shield could be used with confidence in spatial applications. [ABSTRACT FROM AUTHOR]

The objective of this paper was to study the radiation interaction parameters and the degree of weathering of horizons of a Cambisol located in a conservation unit using the percentages of oxides. The oxide contents of the horizons were obtained by employing ED (energy dispersive) and WD (wavelength dispersive) X-ray fluorescence (XRF) techniques, considering that their interpretation of the weathering indices differs according to their resolution. The radiation interaction parameters were calculated using the XCOM computational code, which allowed us to obtain the following parameters: µ/ρ (mass attenuation coefficient), σA and σE (atomic and electronic cross section), Zeff (effective atomic number) and Nel (electronic density). The results indicated that although both techniques proved to be efficient in detecting the levels of oxides, WDXRF was more sensitive. Fe2O3 showed great influence on the parameters µ/ρ, σA and σE, while Zeff and Nel presented no correlations. However, the curves of Zeff and Nel, in the studied energy range (1–100 keV), showed a better distinction between them when compared to the other parameters. The studied Cambisol presented a preserved structure, since it belongs to a conservation unit. Therefore, our findings should be considered a reference result for soils in the region with the same classification and origin, but which were subjected to anthropic action. [ABSTRACT FROM AUTHOR]

Ionizing radiation interaction might occur during diagnostic imaging and radiotherapy procedures. It has been reported that gamma-ray radiation can damage the living cells through the energy transfer. Therefore, investigation the ionization radiation attenuation properties of biomaterials have a crucial importance. In the current study, tungsten disulphide (WS 2) nanopowder-containing borate-based bioactive glass composites were prepared. Their physical, structural, mechanical and ionization radiation attenuation properties were investigated in detail. Monte Carlo simulations and radiation attenuation properties were studied through MCNPX and Phy-X/PSD. Results showed that sintering performed at 575 °C for 1 h in air atmosphere caused formation of some tungsten trioxide in the structure. Addition of WS 2 nanopowders increased the bulk density and improved the mechanical properties of the prepared bioactive glass composites. Simulation studies revealed the influence of WS 2 content on reduction the build-up factors and enhancement of the photon attenuation ability for all the considered photon energies. [ABSTRACT FROM AUTHOR]

In the present work, an experimental study is performed to study the radiation shielding characteristics of SrTiO3 (STO) perovskite ceramic added with different amounts (x = 0, 2, 5, and 10%) of tungsten trioxide nanoparticles (WO3 NPs). The four ceramic samples were prepared using the solid-state reaction method. The structural properties were examined using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The analysis showed the successful formation of WO3- doped STO samples. The crystallite size, estimated using the Scherrer equation, was found in the range of 50.86–41.17 nm. The effect of WO3 NPs on the radiation shielding performance of these ceramics was studied. Different parameters, such as linear attenuation coefficient (LAC) and other related factors, were experimentally determined. The linear attenuation coefficient results demonstrated that the additional amount of WO3 in the ceramics correlates with an improvement in their shielding abilities. The half-value layer (HVL) values for the ceramics with 2% WO3 nanoparticles are equal to 0.071, 1.760, 2.407, and 2.564 cm at 0.060, 0.662, 1.173, and 1.333 MeV, respectively. As the energy increases, more radiation can pass through the material; therefore, a larger thickness is required to absorb half of the total photons, leading to a greater HVL. The tenth value results reaffirmed that increasing the WO3 content in the STO ceramics improves their shielding efficiency. The radiation protection efficiency (RPE) of the four prepared STO ceramics was reported. From the RPE, we found that more photons can be attenuated at lower energies.

Abstract Cancer patients undergoing therapeutic radiation routinely develop injury of the adjacent gastrointestinal (GI) tract mucosa due to treatment. To reduce radiation dose to critical GI structures including the rectum and oral mucosa, 3D‐printed GI radioprotective devices composed of high‐Z materials are generated from patient CT scans. In a radiation proctitis rat model, a significant reduction in crypt injury is demonstrated with the device compared to without (p

Cancer patients undergoing therapeutic radiation routinely develop injury of the adjacent gastrointestinal (GI) tract mucosa due to treatment. To reduce radiation dose to critical GI structures including the rectum and oral mucosa, 3D‐printed GI radioprotective devices composed of high‐Z materials are generated from patient CT scans. In a radiation proctitis rat model, a significant reduction in crypt injury is demonstrated with the device compared to without (p < 0.0087). Optimal device placement for radiation attenuation is further confirmed in a swine model. Dosimetric modeling in oral cavity cancer patients demonstrates a 30% radiation dose reduction to the normal buccal mucosa and a 15.2% dose reduction in the rectum for prostate cancer patients with the radioprotectant material in place compared to without. Finally, it is found that the rectal radioprotectant device is more cost‐effective compared to a hydrogel rectal spacer. Taken together, these data suggest that personalized radioprotectant devices may be used to reduce GI tissue injury in cancer patients undergoing therapeutic radiation. [ABSTRACT FROM AUTHOR]

Erbium (III)- and terbium (III)-containing (1, 3 and 5 wt%) silicate-based bioactive glass powders were synthesized using sol–gel method. Their structural and physical properties were investigated. Radiation attenuation properties of the prepared glass samples were examined using Monte Carlo simulations. The photon transmission properties of the prepared bioactive specimens were obtained via Phy-X PSD program and FLUKA simulation. Results showed that all of the glasses synthesized in the study were amorphous. The true density values were measured in the range of 2.57–2.68 g/cm3. Simulation studies revealed that the lowest neutron cross section was observed for the pure 13–93 bioactive glass sample and the maximum neutron cross section was noted for the prepared bioactive specimens of 5% Er and 5% Tb. Bioactive glass powders synthesized in the study have potential to be used as radiation shielding material in tissue engineering applications. [ABSTRACT FROM AUTHOR]

For the first time, X-ray shielding glass (XSG) was fabricated using rice husk (RH) silica, bismuth, and tin mineral ores. The objective was to promote waste valorisation and circular economy by minimising the use of analytical grade silicon and metal oxides in large-scale radiation shielding glass production. The physical, structural, and low-energy X-ray attenuation properties of the new bismuthite and cassiterites-doped glass were characterised using XRD, FTIR, and low-energy mobile X-ray shielding analyses. The X-ray shielding parameters linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half value layer (HVL), tenth value layer (TVL), and mean free path (MFP) were comparatively examined alongside commercial lead/barium XSG used in hospital radiology units. XRD results showed that glasses with 0, 5 and 15 wt% dopants contain nanocrytallites measuring 19.43, 38.85 and 42.44 nm, respectively, with peaks in the 2Θ (28°) vicinity. FTIR revealed structural modifications that demonstrate the network modulation capabilities of cassiterite-sourced Sn ions. At 70 kVp tube voltage, the MAC of the 20 wt% dopant glass compares favourably with commercial Pb/Ba glass, while the 25 wt% variant has lower values than commercial Pb/Ba glass at 80 kVp tube voltage. The HVL and MFP of 25 wt% dopant glass compared favourably with commercial glass at 60 kVp X-ray tube voltage, suggesting the new glasses with x = 15, 20, 25 wt% dopants are competitive candidates for viewing window applications in low energy X-ray radiology units. Future studies will investigate the radiation attenuation efficiency of the new glass systems using point gamma sources. • Rice Husk silica was extracted for production Xray shielding glasses that is doped with bismuth and tin bearing mineral ores. • The physical, structural, and X-ray attenuation properties of the new glass were investigated. • Comparison with data from commercially available Pb/Ba X-ray shielding glass shows that the new glasses are inexpensive candidates for shielding of viewing windows in low energy radiography and nuclear medicine. [ABSTRACT FROM AUTHOR]

In this study, dose rates and radiation attenuation features of a group of fabricated bioactive glasses were investigated. The borate-based 13-93B3 bioactive glass powders (B3) containing cerium (III), gallium (III) or vanadium (IV) were prepared by melting a homogenized mixture of reagent-grade CaCO3, Na2CO3, MgCO3, K2CO3, H3BO3, CaHPO4.2H2O, Ga2O3, V2O5 or Ce(CH3CO2)3, and disc-shaped scaffolds were prepared by die pressing. Bioactive glasses were modelled by using MCNPX (version 2.7.0) general-purpose Monte Carlo code. A gamma-ray transmission set-up was utilized for determination of mass attenuation coefficients. The obtained coefficients were used for determination of other essential attenuation properties. Finally, exposure (EBF) and energy absorption (EABF) build-up factors were determined. Although the chemical structure of the additive material in bioactive glasses is identical, it can be inferred that the chemical structure of the additive is closely linked to the radiation attenuation characteristics of the bioactive glasses. Results also revealed that, although the bulk densities of the disc-shaped bioactive glass samples were lower than the measured true density values of the melt-derived glass powders due to porosity concerns, they exhibited radiation shielding effect. Findings of the study may be useful in understanding the radiation shielding characteristics of the bioactive glass scaffolds fabricated by powder processing. It can be concluded that outcomes of recent investigation can be useful during the evaluation of potential interactions between the bioactive glasses and medical radiation in the body. [ABSTRACT FROM AUTHOR]

Myosteatosis (pathological fat accumulation in muscle) is defined by lower mean skeletal muscle radiodensity in CT. We aimed to determine the optimal cut-offs for myosteatosis in a cohort of 855 patients with cirrhosis. CT images were used to determine the skeletal muscle radiodensity expressed as Hounsfield Unit (HU). Patients with muscle radiodensity values below the lowest tertile were considered to have myosteatosis. Competing-risk analysis was performed to determine associations between muscle radiodensity and pre-transplant mortality. Muscle radiodensity less than 33 and 28 HU in males and females, respectively, were used as cut-offs to identify myosteatosis. In the univariate analysis, cirrhosis etiology, MELD score, refractory ascites, variceal bleeding, hepatic encephalopathy, sarcopenia and myosteatosis were predictors of mortality. Myosteatosis association with mortality remained significant after adjusting for confounding factors (sHR 1.47, 95% CI 1.17–1.84, p = 0.001). Patients with concurrent presence of myosteatosis and sarcopenia constituted 17% of the patient population. The cumulative incidence of mortality was the highest in patients with concomitant sarcopenia and myosteatosis (sHR 2.22, 95% CI 1.64–3.00, p < 0.001). In conclusion, myosteatosis is common in patients with cirrhosis and is associated with increased mortality. The concomitant presence of myosteatosis and sarcopenia is associated with worse outcomes.

Myosteatosis, or pathological excess fat accumulation in muscle, has been widely defined as a lower mean skeletal muscle radiodensity on computed tomography (CT). It is reported in more than half of patients with cirrhosis, and preliminary studies have shown a possible association with reduced survival and increased risk of portal hypertension complications. Despite the clinical implications in cirrhosis, a standardized definition for myosteatosis has not yet been established. Currently, little data exist on the mechanisms by which excess lipid accumulates within the muscle in individuals with cirrhosis. Hyperammonemia may play an important role in the pathophysiology of myosteatosis in this setting. Insulin resistance, impaired mitochondrial oxidative phosphorylation, diminished lipid oxidation in muscle and age-related differentiation of muscle stem cells into adipocytes have been also been suggested as potential mechanisms contributing to myosteatosis. The metabolic consequence of ammonia-lowering treatments and omega-3 polyunsaturated fatty acids in reversing myosteatosis in cirrhosis remains uncertain. Factors including the population of interest, design and sample size, single/combined treatment, dosing and duration of treatment are important considerations for future trials aiming to prevent or treat myosteatosis in individuals with cirrhosis.

Conventional medical imaging phantoms are limited by simplified geometry and radiographic skeletal homogeneity, which confines their usability for image quality assessment and radiation dosimetry. These challenges can be addressed by additive manufacturing technology, colloquially called 3D printing, which provides accurate anatomical replication and flexibility in material manipulation. In this study, we used Computed Tomography (CT)-based modified PolyJetTM 3D printing technology to print a hollow thorax phantom simulating skeletal morphology of the patient. To achieve realistic heterogenous skeletal radiation attenuation, we developed a novel radiopaque amalgamate constituting of epoxy, polypropylene and bone meal powder in twelve different ratios. We performed CT analysis for quantification of material radiodensity (in Hounsfield Units, HU) and for identification of specific compositions corresponding to the various skeletal structures in the thorax. We filled the skeletal structures with their respective radiopaque amalgamates. The phantom and isolated 3D printed rib specimens were rescanned by CT for reproducibility tests regarding verification of radiodensity and geometry. Our results showed that structural densities in the range of 42–705HU could be achieved. The radiodensity of the reconstructed phantom was comparable to the three skeletal structures investigated in a real patient thorax CT: ribs, ventral vertebral body and dorsal vertebral body. Reproducibility tests based on physical dimensional comparison between the patient and phantom CT-based segmentation displayed 97% of overlap in the range of 0.00–4.57 mm embracing the anatomical accuracy. Thus, the additively manufactured anthropomorphic thorax phantom opens new vistas for imaging- and radiation-based patient care in precision medicine.

The incidence of large-scale fires continues to rise, and the effects of radiation from these fires contributes to their continued spread. Water sprays have been widely used as an effective method to contain thermal radiation from fires. Results from previous studies on the sizes of water droplets in the spray barrier have limitations due to the significant computational time or complex analytical procedure involved. The aim of this study is to determine the optimal size of water droplets in the barrier mist using radiative transfer analysis for effective shielding of the radiation from the surroundings. The radiative properties of water droplets were analyzed using the Mie scattering theory and a radiative transfer analysis of the mist layer was performed. This demonstrated that the spectral reflectance of the mist layer can be controlled by the water droplet diameter. The effectiveness of optimizing the water droplet size in the mist layer to maximize protection from thermal radiation was also validated by experiments to evaluate the radiation shielding performance of the mist barrier. [ABSTRACT FROM AUTHOR]

The features of the electron-probe energy-dispersive spectra of several powder materials are studied. Comparing the experimental results with published data, it is established that the effect of a difference in absorption is the main factor that affects the results of quantitative analysis. To describe the peculiarities of attenuation of the intensity of X-ray photons in powders, a theoretical absorption model is proposed and tested. In the described model, the surface of a sample is considered to be a combination of a large number of randomly oriented planes. The experimental data and simulation results are compared by analyzing the ratio of diagnostic-line intensities. The proposed model of attenuation of the characteristic radiation intensity in the powders agrees well with the experimental data. A mathematical method for taking into account the surface roughness can be used in computer algorithms for simulating the characteristic X-ray radiation and can be included in software for electron-probe analysis as an additional corrector in calculation of the elemental composition of the powder materials. [ABSTRACT FROM AUTHOR]

This paper focuses on the evaluation of the radiation attenuation properties of 15CaF 2 -10CaO-5B 2 O 3 -(65-x)P 2 O 5 -xNiO-5BaO (where 0 ≤ x ≤ 1.0 mol%) bioactive glasses. The radiation attenuation features of these glasses were investigated by determining different factors including mass attenuation coefficient (μ/ρ), exposure and absorption buildup factors (EBF and EABF), neutron removal cross section (NRCS), and effective atomic number (Z eff) for photon, proton, and carbon ion interactions. Geant4 toolkit and Phy-X program were employed for simulations and calculations procedures. The results revealed that NiO content in the studied bioactive glasses has a significant effect on photon interaction and an insignificant effect on the charged particle interactions. The Z eff values of the studied glasses were observed in the range of 18–20 for photon interaction, 10.7–10.9 for proton interaction, and 10.0–10.7 for carbon ion interaction. The NRCS values were 0.087, 0.088, 0.089, 0.090, and 0.091 cm-1 for x = 0, 0.4, 0.6, 0.8 and 1.0 mol%, respectively. The studied bioactive glasses showed a good ability to attenuate gamma radiation at energies of medical applications. [ABSTRACT FROM AUTHOR]

Airborne hyperspectral remote sensing is an important application in the ecological monitoring of the environment in mining areas, and accurate preprocessing of the original images is the key to quantitative information retrieval. The original image data need radiation correction to acquire surface reflectance data. Due to the impact of the field angle, incidental radiance, and the bidirectional reflectance distribution function (BRDF), there can be a brightness gradient between adjacent strips, which leads to radiance difference and obvious chromatic aberration of the mosaicked images. We propose a novel data correction method for seamless mosaicking of airborne hyperspectral images. Firstly, visible and near-infrared (VNIR) and shortwave infrared (SWIR) sensors are calibrated in the laboratory, and the radiation calibration model of the sensor is established by an integrating-sphere system. A correction function is then established by combining the BRDF effect and the radiation attenuation coefficients. We also normalize the exposure time, sun altitude angle, and sensor altitude angle according to the flight strip. The results showed that this method is able to eliminate the signal distortion, allowing the seamless mosaicking of 37 strip images which were taken in different date and conditions in the study area. After the atmospheric correction of the imagery was completed, the accuracy of the preprocessing results was evaluated by field-measured ASD spectroradiometer data. The coefficient of determination R2 of the results for the reflectance was greater than 0.9. The experiments show that the proposed method has a good performance in radiation accuracy, and can provide high-quality hyperspectral data for the follow-up application of the ecological monitoring of a mining area. [ABSTRACT FROM AUTHOR]