Lead-free bismuth glass system towards eco-friendly radiation shielding applications

In this study, the gamma-ray photon, electron, proton, helium ion, carbon ion, thermal neutron, and fast neutron interaction parameters of the (70-x)(Bi2O3 + ZnO) + x(V2O5 + TeO2) + 20B2O3 + 6.5SiO2 + 2.5Al2O3 + 1(CeO2 + Sb2O3) glass system were estimated with the aim of assessing their radiation shielding potentials. The mass attenuation coefficients (MACs) of the glasses were estimated for photon energies between 0.015 and 15 MeV using the PHITS simulation code and XCOM software. The stopping powers of charged radiation such as electrons, protons, α-particles, and carbon ions were also estimated by Monte Carlo simulation of particle transport using PHITS. The narrow beam transmission simulated using PHITS yielded values of MAC that were not so different from those from XCOM. The MACs of B/V-ZBVSA1 vary from 0.039–90.747 cm2/g, while those of B/V-ZBVSA2, B/V-ZBVSA3, and B/V-ZBVSA4 vary from 0.035–69.724, 0.036–73.088, and 0.037–70.597 cm2/g, respectively. The HVL of the glasses varied from 0.011–2.56 cm, 0.019–3.69 cm, 0.017–3.31 cm, and 0.017–3.36 cm for B/V-ZBVSA1 – B/V-ZBVSA4, respectively The effective atomic number varied within the limits: 28.36–76.06, 19.67–67.91, 22.14–68.70, and 22.39–68.08 for BV-ZBVSA1 – BV-ZBVSA4, respectively. The stopping powers (Sp) of electrons in BV-ZBVSA1, BV-ZBVSA2, BV-ZBVSA3, and BV-ZBVSA4 were in the range 1.219–8.043 MeVcm2/g, 1.295–9.306 MeVcm2/g, 1.264–8.859 MeVcm2/g, and 1.257–8.793 MeVcm2/g correspondingly. Comparatively, the Sp of protons, α-radiation, and carbon ions follows the order: BV-ZBVSA2 > BV-ZBVSA3 > BV-ZBVSA4 > BV-ZBVSA1. Also, the value of ΣR for BV-ZBVSA1, BV-ZBVSA2, BV-ZBVSA3, and BV-ZBVSA4 was 0.1171, 0.1126, 0.1133, and 0.1103 cm−1 accordingly, while the corresponding total cross-section of thermal neutrons was 67.6227, 46.8356, 59.1179, and 56.6994 cm−1. The present glasses showed superiority in absorbing photons and neutrons compared to some existing shields and previously recommended glasses. The present glassy samples, thus, can be adopted for radiation protection purposes, among others in radiation facilities

Conductive natural and waste rubbers composites-loaded with lead powder as environmental flexible gamma radiation shielding material

It is well known that materials with lead (Pb) content are very effective as protective materials against radiation. Natural rubber (NR) has been loaded with 30 phr of N220 black (critical concentration) as a conductive and reinforcing filler. These rubber matrices are loaded with different concentrations of Pb powder (up to 100 phr) as filler. Gamma attenuation study was carried out using 3″ × 3″ NaI (Tl) (scintillation detector) gamma-ray spectrometer for (Cs-137), (Co-60), (Ba-133), and (Eu-152). The effect on the shielding property of Pb/NR composite was studied by varying the content of Pb and photon energy. It was found that the addition of Pb filler remarkably increases the linear attenuation coefficient ( μ ) of Pb/NR composites, especially for low photon energy. Linear attenuation coefficient experimental measures and theoretical calculations (using the XCOM code) were performed. It was noted that there is a reasonable agreement between measured and calculated results. In this paper, gamma-ray radiation shielding parameters are also studied for composites based on waste rubber. Its experimental results showed that Pb/W/NR composites have better γ shielding ability compared to Pb/NR ones at the Pb contents so, these are promising materials for fabricating protecting clothes against radiation in addition to their low cost and effective aid to get a clean environment

Gamma-Ray Attenuation and Exposure Buildup Factor of Novel Polymers in Shielding Using Geant4 Simulation

Polymers are often used in medical applications, therefore, some novel polymers and their interactions with photons have been studied. The gamma-ray shielding parameters for Polymethylpentene (PMP), Polybutylene terephthalate (PBT), Polyoxymethylene (POM), Polyvinylidenefluoride (PVDF), and Polychlorotrifluoroethylene (PCTFE) polymers were determined using the Geant4 simulation and discussed in the current work. The mass attenuation coefficients (μ/ρ) were simulated at low and high energies between 0.059 and 1.408 MeV using different radionuclides. The accuracy of the Geant4 simulated results were checked with the XCOM software. The two different methods had good agreement with each other. Exposure buildup factor (EBF) was calculated and discussed in terms of polymers under study and photon energy. Effective atomic number (Zeff) and electron density (Neff) were calculated and analyzed at different energies. Additionally, the half-value layer (HVL) of the polymers was evaluated, and the results of this parameter showed that PCTFE had the highest probability of interaction with gamma photons compared to those of the other tested polymers

Whole-genome sequencing reveals host factors underlying critical COVID-19

Altres ajuts: Department of Health and Social Care (DHSC); Illumina; LifeArc; Medical Research Council (MRC); UKRI; Sepsis Research (the Fiona Elizabeth Agnew Trust); the Intensive Care Society, Wellcome Trust Senior Research Fellowship (223164/Z/21/Z); BBSRC Institute Program Support Grant to the Roslin Institute (BBS/E/D/20002172, BBS/E/D/10002070, BBS/E/D/30002275); UKRI grants (MC_PC_20004, MC_PC_19025, MC_PC_1905, MRNO2995X/1); UK Research and Innovation (MC_PC_20029); the Wellcome PhD training fellowship for clinicians (204979/Z/16/Z); the Edinburgh Clinical Academic Track (ECAT) programme; the National Institute for Health Research, the Wellcome Trust; the MRC; Cancer Research UK; the DHSC; NHS England; the Smilow family; the National Center for Advancing Translational Sciences of the National Institutes of Health (CTSA award number UL1TR001878); the Perelman School of Medicine at the University of Pennsylvania; National Institute on Aging (NIA U01AG009740); the National Institute on Aging (RC2 AG036495, RC4 AG039029); the Common Fund of the Office of the Director of the National Institutes of Health; NCI; NHGRI; NHLBI; NIDA; NIMH; NINDS.Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care or hospitalization after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes-including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)-in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease