A Positive-Ion Reaction Mechanism for the Radiation Induced Oxidation of Carbon Monoxide in the High Dose Rate Radiolysis of CO–O2 Mixtures

1972 ◽  
Vol 50 (21) ◽  
pp. 3508-3514 ◽  
Author(s):  
C. Willis ◽  
A. W. Boyd ◽  
P. E. Bindner
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
High Dose Rate ◽  
High Dose ◽  
Total Oxygen ◽  
Dose Rates ◽  
Electron Scavenger ◽  
Radiation Induced ◽  
A Chain ◽  
Positive Ion

Carbon dioxide and ozone yields have been measured in the irradiation of CO–O2 mixtures with single pulses of electrons. The yields of CO2 at 2 × 1027 ev g−1 s−1 are large G(CO2) = 15 ± 1 from 20–60% O2. These decrease by ∼50% at 1028 eV g−1 s−1. Although the results are somewhat irreproducible the addition of c-C4F8, an electron scavenger, increases these CO2 yields at both dose rates by up to a factor of 15. They are reduced to G(CO2) < 2 by the addition of positive ion scavengers. These results are consistent with a chain reaction similar to that proposed for low dose rate studies involving [Formula: see text], [Formula: see text], and [Formula: see text] as chain carriers.The ozone yields are consistent with a total oxygen atom yield of G(O) = 1.4 in pure CO from neutral processes.

Radiological Control of Gold Octahedral and Prism Nanoparticles

2007 ◽  
Vol 1056 ◽  
Author(s):  
Tina M. Nenoff ◽  
Jason C. Jones ◽  
Paula P. Provencio ◽  
Donald T. Berry
Keyword(s):  
Dose Rate ◽  
High Dose Rate ◽  
Pure Gold ◽  
High Dose ◽  
Visible Absorption ◽  
Dose Rates ◽  
Radiation Induced ◽  
Radiological Control ◽  
Uv Visible ◽  
Short Time

ABSTRACTWe report on a fundamental morphology growth of gold-based nanoparticles by solution radiolysis. Radiolysis of pure gold-polymer solutions of different dose rates and aging time is examined. A detailed description will be presented of the experimentation, testing and analysis. In particular, we will present data on the formation of gold nano-octahedra and -prism particles. The γ-irradiations were carried out with a 60Co source of 1.345 × 105 Ci (Sandia National Laboratories Gamma Irradiation Facility (GIF). Nanoparticle characterization techniques included are UV-vis and TEM. Similar to what has been seen in earlier silver nanoparticle studies, dose rate dictates the size of nanoparticles formed. At high dose rate, all reducing species are produced and scavenged within a short time, and then coalesce into separate nanoparticles. At low dose rate, the coalescence process is faster than the production rate of the reducing radicals. The reduction of radicals occurs mainly on clusters already formed. The differences in the morphologies result from a combination of dose rate, aging and lack of radical scavengers (e.g. isopropyl alcohol), resulting in either gold nano-spheres, octahedral or prism nanoparticles. The progressive evolution with dose rate of the UV-visible absorption spectra of radiation-induced metal clusters is discussed.

scholarly journals Perturbed transcriptional profiles after chronic low dose rate radiation in mice

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256667
Author(s):  
Hildegunn Dahl ◽  
Dag M. Eide ◽  
Torstein Tengs ◽  
Nur Duale ◽  
Jorke H. Kamstra ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Dose Rate ◽  
Low Dose ◽  
High Dose Rate ◽  
High Dose ◽  
Transcriptional Responses ◽  
Transcriptional Profiles ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Genome Wide

Adverse health outcomes of ionizing radiation given chronically at low dose rates are highly debated, a controversy also relevant for other stressors. Increased knowledge is needed for a more comprehensive understanding of the damaging potential of ionizing radiation from all dose rates and doses. There is a lack of relevant low dose rate data that is partly ascribed to the rarity of exposure facilities allowing chronic low dose rate exposures. Using the FIGARO facility, we assessed early (one day post-radiation) and late (recovery time of 100–200 days) hepatic genome-wide transcriptional profiles in male mice of two strains (CBA/CaOlaHsd and C57BL/6NHsd) exposed chronically to a low dose rate (2.5 mGy/h; 1200h, LDR), a mid-dose rate (10 mGy/h; 300h, MDR) and acutely to a high dose rate (100 mGy/h; 30h, HDR) of gamma irradiation, given to an equivalent total dose of 3 Gy. Dose-rate and strain-specific transcriptional responses were identified. Differently modulated transcriptional responses across all dose rate exposure groups were evident by the representation of functional biological pathways. Evidence of changed epigenetic regulation (global DNA methylation) was not detected. A period of recovery markedly reduced the number of differentially expressed genes. Using enrichment analysis to identify the functional significance of the modulated genes, perturbed signaling pathways associated with both cancer and non-cancer effects were observed, such as lipid metabolism and inflammation. These pathways were seen after chronic low dose rate and were not restricted to the acute high dose rate exposure. The transcriptional response induced by chronic low dose rate ionizing radiation suggests contribution to conditions such as cardiovascular diseases. We contribute with novel genome wide transcriptional data highlighting dose-rate-specific radiation responses and emphasize the importance of considering both dose rate, duration of exposure, and variability in susceptibility when assessing risks from ionizing radiation.

Carbon monoxide yields in the radiolysis of carbon dioxide at very high dose rates

1970 ◽  
Vol 48 (13) ◽  
pp. 1951-1954 ◽  
Author(s):  
C. Willis ◽  
A. W. Boyd ◽  
P. E. Bindner
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Dose Rate ◽  
Low Dose ◽  
High Dose ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Electron Scavenger ◽  
The Difference ◽  
Carbon Monoxide Yield

Carbon dioxide has been irradiated with electron pulses at a dose rate of 2 × 1027 eV g−1 s−1. The measured carbon monoxide yield is G(CO) = 7.8 ± 0.3. Addition of SF6, an electron scavenger, reduces this yield to G(CO) = 4.8 which is the same, within the experimental error, as the low dose rate yield G(CO) = 4.5 ± 0.5. The effect of SF6 and the difference between the high and low dose rate yields is explained by suppression of dissociative neutralization of the C2O4+ ion.

scholarly journals Gene expression profiling in undifferentiated thyroid carcinoma induced by high-dose radiation

2016 ◽  
Vol 57 (3) ◽  
pp. 238-249 ◽  
Author(s):  
Hyun Soon Bang ◽  
Moo Hyun Choi ◽  
Cha Soon Kim ◽  
Seung Jin Choi
Keyword(s):  
Gene Expression ◽  
Gene Expression Profiling ◽  
Dose Rate ◽  
Expression Profiling ◽  
Low Dose ◽  
High Dose Rate ◽  
Human Thyroid ◽  
High Dose ◽  
Low Dose Rate ◽  
Radiation Induced

Abstract Published gene expression studies for radiation-induced thyroid carcinogenesis have used various methodologies. In this study, we identified differential gene expression in a human thyroid epithelial cell line after exposure to high-dose γ-radiation. HTori-3 cells were exposed to 5 or 10 Gy of ionizing radiation using two dose rates (high-dose rate: 4.68 Gy/min, and low-dose rate: 40 mGy/h) and then implanted into the backs of BALB/c nude mice after 4 (10 Gy) or 5 weeks (5 Gy). Decreases in cell viability, increases in giant cell frequency, anchorage-independent growth in vitro , and tumorigenicity in vivo were observed. Particularly, the cells irradiated with 5 Gy at the high-dose rate or 10 Gy at the low-dose rate demonstrated more prominent tumorigenicity. Gene expression profiling was analyzed via microarray. Numerous genes that were significantly altered by a fold-change of &gt;50% following irradiation were identified in each group. Gene expression analysis identified six commonly misregulated genes, including CRYAB, IL-18, ZNF845, CYP24A1, OR4N4 and VN1R4, at all doses. These genes involve apoptosis, the immune response, regulation of transcription, and receptor signaling pathways. Overall, the altered genes in high-dose rate (HDR) 5 Gy and low-dose rate (LDR) 10 Gy were more than those of LDR 5 Gy and HDR 10 Gy. Thus, we investigated genes associated with aggressive tumor development using the two dosage treatments. In this study, the identified gene expression profiles reflect the molecular response following high doses of external radiation exposure and may provide helpful information about radiation-induced thyroid tumors in the high-dose range.

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