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At least 757 records · Page 42

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NASA NTRS2017

DNA Repair Domain Modeling Can Predict Cell Death and Mutation Frequency for Wide Range Spectrum of Radiation

Exploration missions to Mars and other destinations raise many questions about the health of astronauts. The continuous exposure of astronauts to galactic cosmic rays is one of the main concerns for long-term missions. Cosmic ionizing radiations are composed of different ions of various charges and energies notably, highly charged energy (HZE) particles. The HZE particles have been shown to be more carcinogenic than low-LET radiation, suggesting the severity of chromosomal aberrations induced by HZE particles is one possible explanation. However, most mathematical models predicting cell death and mutation frequency are based on directly fitting various HZE dose response and are in essence empirical approaches. In this work, we assume a simple biological mechanism to model DNA repair and use it to simultaneously explain the low- and high-LET response using the exact same fitting parameters. Our work shows that the geometrical position of DNA repair along tracks of heavy ions are sufficient to explain why high-LET particles can induce more death and mutations. Our model is based on assuming DNA double strand breaks (DSBs) are repaired within repair domain, and that any DSBs located within the same repair domain cluster into one repair unit, facilitating chromosomal rearrangements and increasing the probability of cell death. We introduced this model in 2014 using simplified microdosimetry profiles to predict cell death. In this work, we collaborated with NASA Johnson Space Center to generate more accurate microdosimetry profiles derived by Monte Carlo techniques, taking into account track structure of HZE particles and simulating DSBs in realistic cell geometry. We simulated 224 data points (D, A, Z, E) with the BDSTRACKS model, leading to a large coverage of LET from ~10 to 2,400 keV/μm. This model was used to generate theoretical RBE for various particles and energies for both cell death and mutation frequencies. The RBE LET dependence is in agreement with experimental data known in human and murine cells. It suggests that cell shape and its orientation with respect to the HZE particle beam can modify the biological response to radiation. Such discovery will be tested experimentally and, if proven accurate, will be another strong supporting evidence for DNA repair domains and their critical role in interpreting cosmic radiation sensitivity.

Viger, Louise↗

DOE OSTI2025

The inorganic chemist's guide to actinide radiation chemistry: a review

This review aims to provide an overview of the current state of radiation chemistry with respect to the actinide elements, thorium through californium. Despite the inherent radioactivity of the actinides, only a few studies explore the effects of ionizing radiation on their redox chemistry and surrounding environment. This fundamental knowledge gap, coupled with the current renaissance in actinide-based technologies such as nuclear power, space exploration, and medicine, underscores the importance of research in this interdisciplinary area. This review will focus on the interactions between reactive species formed by radiolysis with actinides and their complexes, offering an inorganic chemist's perspective on research in radiation chemistry. In addition, a thorough discussion of our current understanding of radiation-induced changes in actinide speciation in both aqueous solution and the solid-state will be provided, focusing on changes in oxidation state distribution, complexation, and secondary coordination effects within inorganic materials. Finally, this review will discuss challenges and opportunities for inorganic chemists to explore this unique intersection of fields.

Actinides↗

NASA NTRS1991

P0004-1 quick look

The P0004-1 'Seeds in Space' experiment consisted of six sealed aluminum canisters which contained tomato seeds and a variety of other seeds for the study of space radiation effects on the seeds. The seeds were contained in cloth bags. Interspersed among the bags of seeds were ten dosimeter packets to monitor the accumulated ionizing radiation exposure of the seeds. In addition to the ten flight dosimeter packets, four ground control packets and one ground movement packet were also included as part of the experiment. The P0004-1 experiment was mounted on the F2 tray, near the trailing edge of the LDEF orbiter. The results indicate that the neutron fluences were higher in the P0004 canisters than in that of P0006. The difference was much greater for thermal neutrons than resonance neutrons. This is consistent with shielding.

Source record↗

NASA NTRS1998

Theoretical Studies of Starburst Infrared Emission: Luminosity Indicators in Dusty Photoionized Environments

The luminosity of the central source in ionizing radiation is an essential parameter in a photoionized environment and is one of the most fundamental physical quantities one can measure. We outline a method of determining the luminosity for any emission-line region using only infrared data. In dusty environments, grains compete with hydrogen in absorbing continuum radiation. Grains produce infrared emission, and hydrogen produces recombination lines. We have computed a very large variety of photoionization models, using ranges of abundances, grain mixtures, ionizing continua, densities, and ionization parameters. The conditions were appropriate for such diverse objects as H(II) regions, planetary nebulae, starburst galaxies, and the narrow- and broad-line regions of active nuclei. The ratio of the total thermal grain emission relative to H-Beta (IR/H-Beta) is the primary indicator of whether the cloud behaves as a classical Stroemgren sphere (a hydrogen-bounded nebula) or whether grains absorb most of the incident continuum (a dust-bounded nebula). We find two global limits: when IR/H-Beta < 100, infrared recombination lines determine the source luminosity in ionizing photons; when IR/H-Beta >> 100, the grains act as a bolometer to measure the luminosity.

Bottorff, Mark↗

NASA NTRS2002

A Radiation Safety Analysis for Lunar Lava Tubes

The purpose of this work is an assessment of the lunar lava tubes physical characteristics and an evaluation of the their actual safety features from the point of view of the ionizing radiation environment as potential habitats for future lunar exploration crews. Additional information is contained in the original extended abstract.

DeAngelis, G.↗

NASA NTRS1990

Negative radiation in partially ionized gas

A stationary, nonlinear collisional-radiative model for high-temperature atomic oxygen is presented. Populations of negative ions, electrons, positive ions and excited atoms and intensities of spectral, continuum and dielectronic recombination radiation are calculated in a wide range of conditions. Calculated total continuum emission is in good agreement with existing measurements. The contribution of the negative ion emission to the total continuum emission is found to be significant.

Soon, W. H.↗

NASA NTRSDate not supplied

Outcomes of a Mini Technical Interchange Meeting Concerning the Risk of Cardiovascular Disease from Exposure to Space Radiation

The NASA Human Research Program’s (HRP) Space Radiation Element (SRE) funds research to characterize and mitigate adverse health outcomes from exposure to space radiation to enable deep space exploration and sustained human presence in space. Damage to the cardiovascular system has been observed after exposure to clinically relevant doses of ionizing radiation. However, an association between lower radiation doses and cardiovascular disease (CVD) remains controversial, and questions pertaining to dose thresholds, radiation quality and dose-rate effects, and gaps in characterizing the mechanisms and major pathways of CVD remain. To solicit new ideas for characterizing and mitigating this risk, the SRE is organizing a series of miniature technical interchange meeting (Tiny-TIM) that provide a venue for HRP-funded investigators and thought leaders to present ongoing work and engage in open discussion on relevant topics. The initial Tiny-TIM: Upping the Ante on Characterizing and Mitigating Cardiovascular Disease Risk from Space Radiation Exposure, held at the NASA HRP Investigators’ Workshop (IWS) earlier this year, consisted of two 90-minute sessions; the first focused on current knowledge of CVD risk from space radiation exposure, and the second focused on innovative ideas, and newer approaches and techniques to accelerate research. The second session was followed by an open, spirited discussion amongst peers on the current issues impeding the characterization of CVD risk. SRE leadership facilitated the discussion using a set of pressing questions and gaps in knowledge that need to be addressed by the scientific community. This poster presents the outcomes of the Tiny-TIM, along with proposed future workshops and the SRE’s other initiatives.

Janapriya Saha↗

NASA NTRS1978

Ames collaborative study of cosmic ray neutrons - Mid-latitude flights

Three aircraft flights at 12.5 km have yielded data on cosmic-ray neutron-flux densities, neutron dose equivalent rates, and exposure rates for ionizing radiation. The data, collected at 45, 38, and 48 degrees N, indicate: (1) neutron dose equivalent rates of 0.20, 0.14, and 0.22 mrem/hour, (2) exposure rates from the ionizing component of 0.37, 0.31, and 0.41 mR/hour, (3) that the dose equivalent from 3-13-MeV neutrons is 30% of the total for all neutrons, (4) that exposure rates decrease exponentially with decreasing pressure altitude with a 140 g/sq cm attenuation length at 43 degrees N geomagnetic latitude, and (5) that the ionizing component of cosmic ray secondaries is less sensitive to latitude changes than the neutron component.

Hewitt, J. E.↗

NASA NTRS1979

Radiation damage in high-voltage silicon solar cells

Three types of open circuit high voltage solar cells were tested to determine their performance after exposure to 1 MeV electron irradiations. The cells with a relatively deep n-type emitter were more susceptible to radiation damage than other high open circuit high voltage cells. The use of diffused or ion implanted junctions leads to open circuit high voltage cell designs that are less susceptible to radiation damage. These latter two types of cells show degradations that are typical of the 0.1 ohm-cm material from which they are fabricated. Furthermore, exposure to ionizing radiation causes oxide degradation and decreased cell performance in cells that depend on a charged oxide to achieve significant cell properties. Hence, the combination of a charged oxide and a relatively deep n-type emitter is not recommended for incorporation into a cell designed for use in the particulate radiation environment of space.

Weinberg, I.↗

NASA NTRS1987

Effects of Radiation on Capacitor Dielectrics

Data gathered on key design parameters. Report discusses study of electrical and mechanical properties of irradiated polymer dielectric materials. Data compiled for use by designers of high-energy-density capacitors that operate in presence of ionizing radiation. Study focused on polycarbonates, polyetheretherketones, polymethylpentenes, polyimides (including polyetherimide), polyolefins, polysulfones (including polyethersulfone and polyphenylsulfone), and polyvinylidene fluorides.

Bouquet, F. L.↗

NASA NTRS2010

Preliminary Evaluation of Commercial Off the Shelf (COTS) Packing Materials for Flight Medication Dispenser (FMD) Technology Development

With the advent of longer duration space missions, pharmaceutical use in space has increased. During the first 33 space shuttle missions, crew members took more than 500 individual doses of 31 different medications . Anecdotal reports from crew members described medications as generally "well tolerated" and "effective". However, reported use of increased medication doses and discrepancies in ground vs. flight efficacy may result from reduced potency or altered bioavailability due to changes in chemical and/or physical parameters of pharmaceutical stability. Based on preliminary results from a ground-based irradiation and an inflight study on pharmaceutical stability, three susceptible medications, Amoxicillin/Clavulanate and Sulfamethoxazole/trimethoprim antibiotics tablets and promethazine (PMZ), an antihistamine were selected for testing using two types of Oliver-Tolas bags, TPC-1475(Clear) and TPF-0599B (Foil) for radiation Shielding effectiveness. The material composition of the bags included aluminum coated Mylar sheathing coated with multifunctional nanocomposities based on polyethylene with dispersed boron-rich nanophases. Two bags of each medication were irradiated for different time intervals with 14.6 rad/min to achieve 0.1 Gy, 1 Gy and 10 Gy of cumulative radiation dose. Active pharmaceutical content (API) in each medication was determined and results analyzed. No significant difference in API content was observed between control and irradiated samples for both antibiotic tablets suggesting both types of bags may offer protection against gamma radiation; results with PMZ were inconclusive. These preliminary results suggest that Oliver-Tolas TPL-1475 and TPF-0599B materials may possess characteristics suitable for protection against ionizing radiation and can be considered for designing and further testing of FMD technology.

Du, Brian↗

DOE OSTI2025

Radiation Effects on the Performance of Advanced Sulfur Monochloride Chlorination Processes

Advanced sulfur chloride-based chlorination technologies are being developed to enable efficient recycling of aluminum and zirconium-based materials used in the nuclear industry. However, the impacts of ionizing radiation on the performance of these sulfur chloride compounds are not well established, despite this being critical knowledge for assessing their feasibility and longevity under envisioned process conditions. Here, in the present article, we report on the effects of cobalt-60 gamma irradiation (≤ 5 MGy) on the aluminum alloy 6061 (AA6061-T6) chlorination yield in sulfur monochloride (S 2 Cl 2 ). Our findings indicate that, compared to nonirradiated solvent, radiation-induced changes in the chemical composition of S 2 Cl 2 —identified using Raman spectroscopy—afford an additional, dose-dependent exothermic process prior to the chlorination reaction’s typical thermodynamic behavior. We attribute this new process to reactions involving aluminum species (metal, oxide, or [oxy]hydroxides) and sulfur dichloride (SCl 2 ), an S 2 Cl 2 radiolysis product that accumulates with absorbed gamma dose, but is absent following an AA6061-T6 chlorination study. Despite the exothermicity of this new process, the overall yield of chlorination decreased with increasing preirradiation dose. Consequently, the chemical reactivity, specificity (aluminum metal vs aluminum passivation and corrosion layer constituents), and byproducts of SCl 2 must be more thoroughly evaluated to support the continued development of advanced S 2 Cl 2 chlorination technologies.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

NASA NTRS1997

Csa-19, a radiation-responsive human gene, identified by an unbiased two-gel cDNA library screening method in human cancer cells

A novel polymerase chain reaction (PCR)-based method was used to identify candidate genes whose expression is altered in cancer cells by ionizing radiation. Transcriptional induction of randomly selected genes in control versus irradiated human HL60 cells was compared. Among several complementary DNA (cDNA) clones recovered by this approach, one cDNA clone (CL68-5) was downregulated in X-irradiated HL60 cells but unaffected by 12-O-tetradecanoyl phorbol-13-acetate, forskolin, or cyclosporin-A. DNA sequencing of the CL68-5 cDNA revealed 100% nucleotide sequence homology to the reported human Csa-19 gene. Northern blot analysis of RNA from control and irradiated cells revealed the expression of a single 0.7-kilobase (kb) messenger RNA (mRNA) transcript. This 0.7-kb Csa-19 mRNA transcript was also expressed in a variety of human adult and corresponding fetal normal tissues. Moreover, when the effect of X- or fission neutron-irradiation on Csa-19 mRNA was compared in cultured human cells differing in p53 gene status (p53-/- versus p53+/+), downregulation of Csa-19 by X-rays or fission neutrons was similar in p53-wild type and p53-null cell lines. Our results provide the first known example of a radiation-responsive gene in human cancer cells whose expression is not associated with p53, adenylate cyclase or protein kinase C.

NASA Discipline Radiation Health↗

DOE OSTI2023

Beam Test Results of the RADiCAL—A Radiation Hard Innovative EM Calorimeter

High-performance calorimetry conducted at future hadron colliders, such as the FCC-hh, poses a significant challenge for applying current detector technologies due to unprecedented beam luminosities and radiation fields. Solutions include developing scintillators that are capable of separating events at the sub-fifty picosecond level while also maintaining performance after extreme and constant neutron and ionizing radiation exposure. The radiation-hard innovative calorimeter (RADiCAL) is an approach that incorporates radiation tolerant materials in a sampling “shashlik”-style calorimeter configuration, using quartz capillaries filled with organic liquid or polymer-based wavelength shifters embedded in layers of tungsten plates and lutetium-yttrium oxyorthosilicate (LYSO) crystals. Here, this novel design intends to address the priority research directions (PRD) for calorimetry listed in the DOE basic research needs (BRN) workshop for high energy physics (HEP) instrumentation. Here we report preliminary results from an experimental run at the Fermilab Test Beam Facility (FTBF) in June 2022. These tests demonstrate that the RADiCAL concept is capable of ¡50 ps timing resolution.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1977

Satellite Power System (SPS) microwave subsystem impacts and benefits

The impacts and benefits to society of the microwave subsystem resulting from the developing, construction and operating of a space solar power to earth, electric power delivery system are presented and discussed. The primary benefit (usable energy) is conveyed mainly in the fundamental frequency portion of the RF radiation beam that is intercepted and converted to electric power output. The small fraction of the microwave and other electromagnetic energy that does not end up in the electric utility grid, yields most of the subsystem impacts. The impacts range from harmonics and noise radiated by the transmitting antenna, through potential interference with ionospheric communications and navigation caused by the power beam heating the ionosphere, to the potential large land area requirements for the rectennas and low level microwave radiation around the rectennas. Additional benefits range from a very low level of waste heat liberated and lack of atmospheric emissions including noise while operating to having no residual ionizing radiation from the rectenna when it is deactivated.

Dickinson, R. M.↗

NASA NTRS1988

The space radiation environment for electronics

The earth's space radiation environment is described in terms of charged particles as relevant to effects on spacecraft electronics. The nature and magnitude of the trapped and transiting environments are described in terms of spatial distribution and temporal variation. The internal radiation environment of the spacecraft is described in terms of shielding the high-energy particles of the free-field environment. Exposure levels are presented in terms of ionizing radiation dose and particle fluence for comparison to electronic component susceptibility.

Stassinopoulos, E. G.↗

NASA NTRS2007

The Use of Heavy Ion Radiation as an Analog for Space Radiation Environment and Its Effects on Drug Stability

While it is common knowledge that electromagnetic radiation such as x-rays and gamma rays affect physical-chemical characteristics (PC) of compounds in addition to their toxic and mutagenic effects on biological systems, there are no reports on the effects of cosmic radiation encountered during space missions on stability of pharmaceuticals. Alterations in PC of drug formulations can adversely affect treatment with medications in space. Preliminary evaluation of stability and shelf-life of select pharmaceuticals (12) flown on space missions revealed that 37% and 40% of the formulations failed to meet USP requirements after shuttle and ISS flights, respectively. Based on these results, the current investigation is designed to examine the effect of proton (P) and heavy ion (Fe) radiation on 20 pharmaceutical preparations flown aboard the shuttle and ISS. The objectives of this project are: 1) Examine susceptibility of pharmaceuticals to short acute bouts of high intensity ionizing radiation species encountered during space flights; 2) Estimate extent of degradation of susceptible formulations as a function of intensity of each beam (P & Fe); and 3) compare and contrast the effects of single beam irradiation to that of a combined beam (P + Fe) that simulates space craft environment on drug stability. Irradiations were conducted at the Brookhaven National Laboratories (BNL) with beam strengths of 10 cGy, 10 or 50Gy of P and Fe beams separately. Preliminary evaluation of results revealed a reduction in the chemical content of label claim ranging 12-55 % for Augmentin, 7% for promethzine tablets and 9% for ciprofloxacin ointment. These results are in agreement, although less in magnitude than those observed during space flight and after gamma irradiation.

Vaksman, Z.↗

NASA NTRS2007

Modeling the Prodromal Effects and Performance Reduction of Astronauts from Exposure to Large Solar Particle Events

In space exploration outside the Earth's geomagnetic field, radiation exposure from solar particle events (SPE) presents a health concern for astronauts, that could impair their performance and result in possibility of failure of the mission. Acute risks are especially of concern during spacewalks on the lunar surface because of the rapid onset of SPE's and science goals that involve long distances to crew habitats. Thus assessing the potential of early radiation effect under such adverse conditions is of prime importance. Here we present a biologic based mathematical model which describes the dose and time-dependent early human responses to ionizing radiation. We examine the possible early effects on crew behind various shielding materials from exposure to some historical large SPEs on the lunar and Mars surfaces. The doses and dose rates were calculated using the BRYNTRN code (Kim, M.Y, Hu, X, and Cucinotta, F.A, Effect of Shielding Materials from SPEs on the Lunar and Mars Surface, AIAA Space 2005, paper number AIAA-2005-6653, Long Beach, CA, August 30-September 1, 2005) and the hazard of the early radiation effects and performance reduction were calculated using the RIPD code (Anno, G.H, McClellan, G.E., Dore, M.A, Protracted Radiation-Induced Performance Decrement, Volume 1 Model Development,1996, Defense Nuclear Agency: Alexandria VA). Based on model assumptions we show that exposure to these historical SPEs do cause early effects to crew members and impair their performance if effective shielding and medical countermeasure tactics are not provided. The calculations show multiple occurrence of large SPEs in a short period of time significantly increase the severity of early illness, however early death from failure of the hematopoietic system is very unlikely because of the dose-rate and dose heterogeneity of SPEs. Results from these types of calculations will be a guide in design of protection systems and medical response strategy for astronauts in case of exposure to high dose irradiation during future space missions.

Hu, S.↗