THE EFFECT OF ELECTRIC FIELDS, AND A RELATED DEPENDENCE ON DOSE RATE, IN THE γ-RADIOLYSIS OF HYDROCARBON GASES

1963 ◽  
Vol 41 (6) ◽  
pp. 1463-1468 ◽  
Author(s):  
T. W. Woodward ◽  
R. A. Back
Keyword(s):  
Dose Rate ◽  
Gas Phase ◽  
Electric Fields ◽  
Low Dose ◽  
High Dose ◽  
Hydrogen Yield ◽  
Hydrocarbon Gases ◽  
Saturation Field ◽  
Dose Rates ◽  
And Diffusion

The effect of electric fields on the γ-radiolysis of ethane, propane, and the butanes has been investigated briefly at 800 mm pressure, with dose rates between 2 × 1010 and 400 × 1010 ev/cc sec. Yields of hydrogen were reduced when a saturation field was applied, except with ethane at low dose rate, where a slight increase in hydrogen yield was observed. With propane and n-butane, the yield of hydrogen in the presence of a saturation field was independent of dose rate, while with ethane, it decreased with decreasing dose rate. At the same time, a dose rate dependence was discovered in the simple radiolysis, in the absence of any field, of ethane, propane, and n-butane, a decrease in the yield of hydrogen at low dose rates being observed. An explanation of these observations is suggested in terms of a competition between neutralization of ions in the gas phase and diffusion of ions to the wall. High dose rates should favor the former process, and low dose rates the latter. At sufficiently high dose rates, all ions should be neutralized in the gas phase. At sufficiently low dose rates, all ions should diffuse to the wall before neutralization, and it is suggested that the radiolysis under these conditions should closely resemble that in the presence of a saturation field at higher dose rates.

Isotope effects in the gas phase radiolysis of H2S and D2S

1976 ◽  
Vol 54 (17) ◽  
pp. 2767-2772
Author(s):  
Robert D. McAlpine ◽  
O. A. Miller ◽  
A. W. Boyd
Keyword(s):  
Dose Rate ◽  
Gas Phase ◽  
Isotope Effects ◽  
High Dose ◽  
Dose Rates ◽  
Kinetic Isotope ◽  
A Value ◽  
Straight Line ◽  
Separation Factors ◽  
Very High

Gas phase radiolysis studies have been carried out on mixtures of H2S and D2S using as irradiation sources, either a Gammacell or a Febetron 705 pulsed electron accelerator. Separation factors (α = (H/D)prod ÷ (H/D)react) were obtained for various values of xD (the mole fraction of D2S), dose rate and temperature, as well as with the addition of SF6. All of the observed α values, for 0.2 ≤ xD ≤ 0.8, fall on the following empirical straight line.[Formula: see text]The addition of neon to a D2S/H2S mixture gives a value of α which decreases as the partial pressure of neon increases. For a 70% D2S/30% H2S mixture, &([a-z]+); = 1.9 ± 0.1 for the pure mixture and 1.28 ± 0.08 when 90 kPa of neon has been added to 10 kPa of the mixture. The &([a-z]+); values described by eq. 1 are interpreted as arising from kinetic isotope effects in the reactions of (translationally) hot H or D atoms with H2S, HDS, or D2S to form H2, HD or D2.Hydrogen yields from the gas phase radiolysis of pure H2S and pure D2S have been determined for dose rates from 4 × 1016 to 2 × 1028 eV g−1 s−1. Using dose rates of up to 2 × 1027 eV g−1 s−1, ΔG = G(H2) − G(D2) = 0.5. For the highest dose rate used (2 × 1028 eV g−1 s−1), ΔG = 1.5. The larger value of ΔG at very high dose rates is thought to arise from the dissociative neutralization processes. A possible mechanism 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.

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.

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.

Radiolysis of Hydrogen Sulfide at Very High Dose Rates. The Effect of SF61

1971 ◽  
Vol 49 (10) ◽  
pp. 1677-1682 ◽  
Author(s):  
C. Willis ◽  
A. W. Boyd ◽  
O. A. Miller
Keyword(s):  
Hydrogen Sulfide ◽  
Low Dose ◽  
Single Pulse ◽  
Ion Pair ◽  
High Dose ◽  
Hydrogen Yield ◽  
Dose Rates ◽  
Absorbed Doses ◽  
Electron Pulses ◽  
Very High

Gaseous H2S has been irradiated with electron pulses from a Febetron 705 at a dose rate of ~2 × 1027 eV g−1 s−1. For single pulse experiments, the yield of hydrogen is G(H2) = 12.0 ± 0.5, independent of pressure from at least 350 to 1600 Torr. Addition of SF6 reduces the yield to G(H2) = 7.9 ± 0.3 which is fairly close to that observed for pure H2S at low dose rates. The reduction, ΔG(H2) = 4.1 ± 0.3, agrees very well with the ion pair yield based on a W value of 25.3 eV.In multi-pulse irradiations, for pure H2S, the yield falls off with dose giving a limiting yield close to G(H2) = 8.0. No similar fall-off is observed for H2S–SF6 mixtures. It is proposed that at high absorbed doses and at low dose rates, there is no contribution to the hydrogen yield from neutralization processes; and that this is due to neutralization of H3S+ by an ion of the type Sn− rather than a free electron.

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.

scholarly journals Serum Metabolomic Alterations Associated with Cesium-137 Internal Emitter Delivered in Various Dose Rates

Metabolites ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 270
Author(s):  
Heng-Hong Li ◽  
Yun-Tien Lin ◽  
Evagelia C. Laiakis ◽  
Maryam Goudarzi ◽  
Waylon Weber ◽  
...  
Keyword(s):  
Dose Rate ◽  
Cumulative Dose ◽  
Low Dose ◽  
Biological Effects ◽  
Serum Samples ◽  
Dose Rates ◽  
Sphingosine 1 Phosphate ◽  
Cesium 137 ◽  
Dose Rate Effect ◽  
Medium Dose

Our laboratory and others have use radiation metabolomics to assess responses in order to develop biomarkers reflecting exposure and level of injury. To expand the types of exposure and compare to previously published results, metabolomic analysis has been carried out using serum samples from mice exposed to 137Cs internal emitters. Animals were injected intraperitoneally with 137CsCl solutions of varying radioactivity, and the absorbed doses were calculated. To determine the dose rate effect, serum samples were collected at 2, 3, 5, 7, and 14 days after injection. Based on the time for each group receiving the cumulative dose of 4 Gy, the dose rate for each group was determined. The dose rates analyzed were 0.16 Gy/day (low), 0.69 Gy/day (medium), and 1.25 Gy/day (high). The results indicated that at a cumulative dose of 4 Gy, the low dose rate group had the least number of statistically significantly differential spectral features. Some identified metabolites showed common changes for different dose rates. For example, significantly altered levels of oleamide and sphingosine 1-phosphate were seen in all three groups. On the other hand, the intensity of three amino acids, Isoleucine, Phenylalanine and Arginine, significantly decreased only in the medium dose rate group. These findings have the potential to be used in assessing the exposure and the biological effects of internal emitters.

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