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.

The radiation chemistry of carbon monoxide at very high dose rates

1970 ◽  
Vol 48 (19) ◽  
pp. 3029-3033 ◽  
Author(s):  
C. Willis ◽  
O. A. Miller
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Excited State ◽  
Oxygen Atom ◽  
Dose Rate ◽  
Electron Accelerator ◽  
Radiation Chemistry ◽  
High Dose ◽  
Dose Rates ◽  
Very High

Carbon monoxide has been irradiated with single intense pulses from an electron accelerator at a dose rate of ~ 2 × 1027 eV g−1 s−1. The yield of carbon dioxide obtained was G(CO2) = 0.7 ± 0.1 with a very small yield of carbon suboxide, G(C3O2) ≤ 0.02.Addition of propene reduces the carbon dioxide yield to almost zero while addition of propane has no effect. This suggests that propene is acting as an oxygen atom scavenger rather than as a quencher of an excited state of carbon monoxide. However, rate constant data do not support this suggestion and it is concluded that the residual yield of carbon dioxide observed at high dose rates arises from reaction 9[Formula: see text]where CO+ is in an A2Π or B2Σ+ state.

Radiation chemistry of acetylene at high intensity: the initial product distributions

1977 ◽  
Vol 55 (18) ◽  
pp. 3288-3293 ◽  
Author(s):  
C. Willis ◽  
R. A. Back ◽  
R. H. Morris
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
Product Distribution ◽  
Radiation Chemistry ◽  
Initial Distribution ◽  
High Dose Rate ◽  
High Dose ◽  
Initial Product ◽  
Low Dose Rate ◽  
The Difference

The distribution of products observed in the radiation chemistry of acetylene at high dose rate is dramatically different from that observed at low dose rate. The dominant products observed at high dose rate are vinyl acetylene and diacetylene with C3 to C9 compounds having smaller but significant yields. At low dose rate benzene and cuprene are the exclusive products. The difference in product distribution is attributed to the suppression of secondary attack on products at high dose rate so that the observed distribution approximates more closely the 'zero dose' or 'initial' distribution.

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.

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.

LOW-DOSE-RATE OR HIGH-DOSE-RATE BRACHYTHERAPY IN COMBINATION WITH EXTERNAL BEAM RADIOTHERAPY FOR INTERMEDIATE AND HIGH-RISK PROSTATE CANCER

2018 ◽  
Vol 64 (1) ◽  
pp. 79-83
Author(s):  
Vladimir Solodkiy ◽  
Andrey Pavlov ◽  
Aleksey Tsybulskiy ◽  
Anton Ivashin
Keyword(s):  
Prostate Cancer ◽  
High Risk ◽  
Dose Rate ◽  
Low Dose ◽  
External Beam Radiotherapy ◽  
Combined Treatment ◽  
High Dose ◽  
External Beam ◽  
Low Dose Rate ◽  
Risk Of Progression

Introduction. One of the main problems of modem on-courology is treatment for prostate cancer of intermediate and high risk of progression. Modern radiotherapy in this category of patients has an advantage over surgical methods of treatment. One way to improve the effectiveness of radiotherapy is to escalate the dose in the prostate gland. For this purpose a combination of brachytherapy and remote radiotherapy is used. This combination allows increasing the dose of radiation, thereby providing better local control, reducing complications from neighboring organs. Purpose of the study. To conduct a comparative analysis of efficacy and safety of radical treatment of patients with prostate cancer at medium and high risk of progression using a combination of high and low dose rate brachytherapy with external beam radiotherapy. Materials and methods. 107 patients with prostate cancer of the group of medium and high risk of progression combined treatment (brachytherapy with external beam radiotherapy) was conducted. 53 patients underwent combined treatment (HDR-brachytherapy and external beam radiotherapy). 54 patients underwent combined treatment (LDR-brachytherapy and external beam radiotherapy). The observation period was 5 years. Conclusion. In a comparative analysis in groups of combined radiotherapy with the use of high-dose and low-dose-rate brachytherapy, the same effectiveness of immediate and long-term results of treatment was demonstrated. A significant reduction in early and late toxic reactions in patients with high-power brachytherapy has been demonstrated.

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