{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T05:01:52Z","timestamp":1790226112477,"version":"4.1.0"},"reference-count":31,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T00:00:00Z","timestamp":1790035200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Texas A &M University","award":["TEES TARC 2023"],"award-info":[{"award-number":["TEES TARC 2023"]}],"id":[{"id":"https:\/\/ror.org\/01f5ytq51","id-type":"ROR","asserted-by":"crossref"}]},{"award":["TEES TARC 2023"],"award-info":[{"award-number":["TEES TARC 2023"]}],"id":[{"id":"https:\/\/ror.org\/01f5ytq51","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Prairie View A & M University","id":[{"id":"https:\/\/ror.org\/0449kf092","id-type":"ROR","asserted-by":"crossref"}]},{"id":[{"id":"https:\/\/ror.org\/0449kf092","id-type":"ROR","asserted-by":"publisher"}]},{"name":"DOE MSIPP MATE","award":["DE-NA0004115"],"award-info":[{"award-number":["DE-NA0004115"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nanomaterials"],"abstract":"<jats:p>Radiation shielding is an important consideration in the design and protection of spacecraft electronics and equipment, where conventional metallic shields can add considerable weight and are difficult to integrate with compact or non-planar components. Flexible polymer composites containing high-Z materials offer an alternative approach by combining radiation attenuation with the conformability of an elastomeric matrix. In this work, nano-bismuth is incorporated into a silicone elastomer at loadings of 0\u201330 wt.% to develop a flexible X-ray shielding composite. The shielding performance of the composites is evaluated experimentally under a 160 kV X-ray source at a total dose of 1 Mrad and compared using Geant4 Monte Carlo simulations. The simulation model is then used to investigate a broader range of bismuth concentrations and composite thicknesses and develop an empirical relationship to predict X-ray attenuation. The results show a clear improvement in X-ray attenuation with increasing nano-bismuth content, demonstrating the potential of silicone\/nano-Bi composites as shielding materials for extreme-environment applications, including space.<\/jats:p>","DOI":"10.3390\/nano16191198","type":"journal-article","created":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T08:17:54Z","timestamp":1790065074000},"page":"1198","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Nano-Bismuth\u2013Silicone Polymer Composite as Shielding for X-Rays in Extreme-Environment Applications: Experimental and Simulation Studies"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-3591-5507","authenticated-orcid":false,"given":"Seyyed Saeed","family":"Vaezzadeh","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Prairie View A&M University, Prairie View, TX 77446, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"given":"Mahmudur","family":"Rahman","sequence":"additional","affiliation":[{"name":"Department of Physics, Prairie View A&M University, Prairie View, TX 77446, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"software","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3929-2878","authenticated-orcid":false,"given":"Kalyan Raj","family":"Kota","sequence":"additional","affiliation":[{"name":"Mary Kay O\u2019Connor Process Safety Center, Texas A&M Engineering Experiment Station, College Station, TX 77843, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0751-789X","authenticated-orcid":false,"given":"Masoumeh","family":"Ozmaeian","sequence":"additional","affiliation":[{"name":"Matter Mind Analytics LLC., Austin, TX 78735, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"software","vocabulary":"credit"}]},{"given":"Justin","family":"Carter","sequence":"additional","affiliation":[{"name":"Mary Kay O\u2019Connor Process Safety Center, Texas A&M Engineering Experiment Station, College Station, TX 77843, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3805-1869","authenticated-orcid":false,"given":"Robert Kelley","family":"Bradley","sequence":"additional","affiliation":[{"name":"Department of Industrial and Systems Engineering, Lamar University, Beaumont, TX 77705, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8314-1962","authenticated-orcid":false,"given":"Merlyn Xavier","family":"Pulikkathara","sequence":"additional","affiliation":[{"name":"Department of Physics, Prairie View A&M University, Prairie View, TX 77446, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,22]]},"reference":[{"key":"ref_1","first-page":"17","article-title":"Harsh Environments: Space Radiation Environment, Effects, and Mitigation","volume":"28","author":"Maurer","year":"2008","journal-title":"Johns Hopkins APL Tech. Dig."},{"key":"ref_2","unstructured":"Copeland, K., and Friedberg, W. (2026, September 18). Ionizing Radiation and Radiation Safety in Aerospace Environments, Available online: https:\/\/rosap.ntl.bts.gov\/view\/dot\/57227."},{"key":"ref_3","unstructured":"Kniffin, S. (2026, September 18). Terrestrial Sources of X-Ray Radiation and Their Effects on NASA Flight Hardware, Available online: https:\/\/ntrs.nasa.gov\/api\/citations\/20160014619\/downloads\/20160014619.pdf."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1038\/s41526-023-00262-7","article-title":"Towards sustainable human space exploration\u2014Priorities for radiation research to quantify and mitigate radiation risks","volume":"9","author":"Fogtman","year":"2023","journal-title":"npj Microgravity"},{"key":"ref_5","first-page":"446","article-title":"Shielding protection of electronic circuits against radiation effects of space high energy particles","volume":"3","author":"Zeynali","year":"2012","journal-title":"Adv. Appl. Sci. Res."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Wang, M., Wang, Q., Xiao, Y., Wang, M., Wang, J., Wang, H., and Chen, Z. (2025). Review of passive shielding materials for high-energy charged particles in Earth\u2019s orbit. Materials, 18.","DOI":"10.3390\/ma18112558"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"130","DOI":"10.1007\/s42114-023-00678-5","article-title":"Overview of emerging hybrid and composite materials for space applications","volume":"6","author":"Ince","year":"2023","journal-title":"Adv. Compos. Hybrid Mater."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Blachowicz, T., and Ehrmann, A. (2021). Shielding of cosmic radiation by fibrous materials. Fibers, 9.","DOI":"10.3390\/fib9100060"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"63","DOI":"10.55696\/ejset.1102371","article-title":"Monte-Carlo (MC) analysis of borated materials for neutron shielding applications","volume":"3","author":"Albarodi","year":"2022","journal-title":"Eurasian J. Sci. Eng. Technol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"111585","DOI":"10.1016\/j.radphyschem.2024.111585","article-title":"Neutron transmission analysis in borated polyethylene, boron carbide, and polyethylene: Insights from MCNP6 simulations","volume":"218","author":"Almisned","year":"2024","journal-title":"Radiat. Phys. Chem."},{"key":"ref_11","unstructured":"Thibeault, S.A., Fay, C.C., Lowther, S.E., Earle, K.D., Sauti, G., Kang, J.H., Park, C., and McMullen, A.M. (2026, September 18). Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study\u2014Phase I, Available online: https:\/\/www.nasa.gov\/general\/radiation-shielding-materials-containing-hydrogen-boron-and-nitrogen-systematic-computational-and-experimental-study\/."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"6983","DOI":"10.1002\/pc.29408","article-title":"Gamma-ray and neutron attenuation of carbon fiber\/epoxy composites with carbon nanotubes and boron nitride nanoparticles for passive shielding applications in space","volume":"46","author":"Peker","year":"2025","journal-title":"Polym. Compos."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1016\/j.actaastro.2024.05.020","article-title":"Poly(vinyl alcohol) gels cross-linked by boric acid for radiation protection of astronauts","volume":"221","author":"Lambertini","year":"2024","journal-title":"Acta Astronaut."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"112808","DOI":"10.1016\/j.compositesb.2025.112808","article-title":"Highly stretchable liquid metal\/poly(urethane-urea) composite with self-healing ability for electromagnetic interference shielding","volume":"306","author":"Ma","year":"2025","journal-title":"Compos. Part B Eng."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Hubbell, J.H., and Seltzer, S.M. (1995). Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients 1 keV to 20 MeV for Elements Z = 1 to 92 and 48 Additional Substances of Dosimetric Interest, NISTIR 5632.","DOI":"10.6028\/NIST.IR.5632"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"35510","DOI":"10.1021\/acsami.8b10600","article-title":"Enhanced radiation shielding with conformal light-weight nanoparticle\u2013polymer composite","volume":"10","author":"Li","year":"2018","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e53130","DOI":"10.1002\/app.53130","article-title":"Lightweight and flexible bismuth oxide composite with enhanced x-ray shielding efficiency","volume":"139","author":"Cheraghi","year":"2022","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1038\/s44431-025-00008-3","article-title":"Non-toxic soft shielding materials for wearable X-ray protection","volume":"1","author":"Wang","year":"2025","journal-title":"npj Soft Matter"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1016\/j.nimb.2005.01.001","article-title":"Effects of proton exposure on aluminized Teflon FEP film degradation","volume":"234","author":"Li","year":"2005","journal-title":"Nucl. Instrum. Methods Phys. Res. Sect. B"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1016\/S0168-9002(03)01368-8","article-title":"Geant4, a simulation toolkit","volume":"506","author":"Agostinelli","year":"2003","journal-title":"Nucl. Instrum. Methods Phys. Res. Sect. A"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1063\/1.2720459","article-title":"The MCNPX Monte Carlo radiation transport code","volume":"Volume 896","author":"Waters","year":"2007","journal-title":"AIP Conference Proceedings"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"948","DOI":"10.1016\/j.apradiso.2009.10.019","article-title":"Comparison of SRIM, MCNPX and GEANT simulations with experimental data for thick Al absorbers","volume":"68","author":"Evseev","year":"2010","journal-title":"Appl. Radiat. Isot."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1499","DOI":"10.1118\/1.597408","article-title":"Attenuation Properties of Diagnostic X-Ray Shielding Materials","volume":"21","author":"Archer","year":"1994","journal-title":"Med. Phys."},{"key":"ref_24","unstructured":"(2021). Standard Test Method for Viscosity by Dip-Type Viscosity Cups (Standard No. ASTM D4212-21)."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"N433","DOI":"10.1088\/0031-9155\/54\/19\/N01","article-title":"SpekCalc: A program to calculate photon spectra from tungsten anode x-ray tubes","volume":"54","author":"Poludniowski","year":"2009","journal-title":"Phys. Med. Biol."},{"key":"ref_26","unstructured":"Cullen, D.E., Hubbell, J.H., and Kissel, L. (2026, September 18). EPDL97: The Evaluated Photon Data Library, Available online: https:\/\/www.osti.gov\/servlets\/purl\/295438."},{"key":"ref_27","unstructured":"Perkins, S.T., Cullen, D.E., and Seltzer, S.M. (2026, September 18). Tables and Graphs of Electron-Interaction Cross Sections from 10 eV to 100 GeV Derived from the LLNL Evaluated Electron Data Library (EEDL), Z = 1\u2013100, Available online: https:\/\/www.osti.gov\/servlets\/purl\/5691165-MTkrfb\/."},{"key":"ref_28","unstructured":"Perkins, S.T., Cullen, D.E., Chen, M.H., Rathkopf, J., Scofield, J., and Hubbell, J.H. (2026, September 18). Tables and Graphs of Atomic Subshell and Relaxation Data Derived from the LLNL Evaluated Atomic Data Library (EADL), Z = 1\u2013100, Available online: https:\/\/www.osti.gov\/servlets\/purl\/10121422."},{"key":"ref_29","unstructured":"Heitler, W. (1954). The Quantum Theory of Radiation, Oxford University Press. [3rd ed.]."},{"key":"ref_30","unstructured":"Bevington, P.R., and Robinson, D.K. (2003). 9. Data Reduction and Error Analysis for the Physical Sciences, McGraw-Hill. [3rd ed.]."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1038\/s41592-019-0686-2","article-title":"SciPy 1.0: Fundamental Algorithms for Scientific Computing in Python","volume":"17","author":"Virtanen","year":"2020","journal-title":"Nat. Methods"}],"container-title":["Nanomaterials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-4991\/16\/19\/1198\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T04:25:47Z","timestamp":1790223947000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-4991\/16\/19\/1198"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,22]]},"references-count":31,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2026,10]]}},"alternative-id":["nano16191198"],"URL":"https:\/\/doi.org\/10.3390\/nano16191198","relation":{},"ISSN":["2079-4991"],"issn-type":[{"value":"2079-4991","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,22]]}}}