Intensity Of Ionizing Radiation Research Articles

Synergistic Effects of Ionizing Radiation Process in the Integrated Coagulation–Sedimentation, Fenton Oxidation, and Biological Process for Treatment of Leachate Wastewater

This study evaluated the feasibility of ionizing radiation combined with coagulation–sedimentation and Fenton oxidation as a treatment method for landfill leachate. The experiments revealed a positive correlation between pollutant removal efficiency and increased ionizing radiation intensity. Remarkable pollutant removal efficiencies were achieved under ionizing radiation at 50 kGy, with a maximum of 27% removal of total organic carbon (TOC), 61% removal of total nitrogen, 51% removal of total phosphorus, and an impressive 93% removal of NO3−-N. With the addition of coagulation–sedimentation and Fenton oxidation, the treatment efficiency further increased by 33% nitrogen, 18% SCOD, and 8% phosphate. The most significant observation from the study was that for all the different treatment methods, the results were always better for leachate samples treated with ionizing radiation than for the untreated samples. Subsequently, biological treatment was applied as a post-treatment method to remove residual organic carbon and nitrogen, which found that the best removal efficiencies were only for the low salt concentration (0.5%) and the removal decreased with increasing salt concentration. These experimental results conclusively demonstrated that when treating leachate wastewater, it was more appropriate to employ physicochemical methods rather than a biological treatment, primarily due to the high salt concentration present.

Formal verification confirms the role of p53 protein in cell fate decision mechanism

The bio-cell cycle is controlled by a complex biochemical network of signaling pathways. Modeling such challenging networks accurately is imperative for the understanding of their detailed dynamical behavior. In this paper, we construct, analyze, and verify a hybrid Petri net (HPN) model of a complex biochemical network that captures the role of an important protein (namely p53) in deciding the fate of the cell. We model the behavior of the cell nucleus and cytoplasm as two stochastic and continuous Petri nets, respectively, combined together into a single HPN. We use simulative model checking to verify three different properties that capture the dynamical behavior of p53 protein with respect to the intensity of the ionizing radiation (IR) to which the cell is exposed. For each IR dose, 1000 simulation runs are carried out to verify each property. Our verification results showed that the fluctuations in p53, which relies on IR intensity, are compatible with the findings of the preceding simulation studies that have previously examined the role of p53 in cell fate decision.

Preliminary assessment of genotoxic effects induced by radiation from EAST using Vicia faba micronucleus assay

During long-pulse deuterium plasma operations in the Experimental Advanced Superconducting Tokamak (EAST), a mixed radiation field is generated, which is mainly composed of fusion neutrons, gamma rays, and x-rays. More accurate and effective dose monitoring methods have been developed and established to determine the ionizing radiation intensity both for the stable operation of the device and for the radiation safety of personnel. As far as we know, there are few reports about the biological effects of radiation induced by fusion neutrons and γ radiation, which are of vital importance for the assessment of radiation hazards presented by fusion devices, such as EAST, to human beings and the environment. In this study, three positions in the EAST hall were selected to detect genotoxic effects induced by nuclear fusion radiation using a Vicia faba micronucleus (MN) test for the first time. The doses of neutrons and gamma rays at these places were measured by thermoluminescence dosimeters four times between June 2019 and May 2020. The radiation doses decreased as the distances from the EAST device shell gradually increased from S1 to S3. The radiation in the EAST hall resulted in a significant induction of MN in the Vicia faba root tip cells compared to a negative control, which was different from the MN frequency induced by fission neutrons, γ-rays and other kinds of radiation in previous studies. These results indicate the existence of potential genotoxic effects induced by radiation from EAST which is different from other radiation and suggest that personnel should not be permitted to enter the experimental hall during the discharge process, and that radiation protection measures should be taken during necessary maintenance to avoid radiation damage. These newly acquired results will certainly increase our knowledge about the biological effects induced by radiation from nuclear fusion and provide good data support for developing more effective environmental and personnel fusion radiation protection.

The Effect of the Ionizing Radiation Intensity on the Response of MOS Structures

The effect of the intensity of ionizing radiation on the volume charge and surface-state density of metal—oxide—semiconductor (MOS) structures with thin gate silicon dioxide is modeled. It is shown that the dependences of the surface-state density and volume charge on the total time of ionizing radiation and subsequent annealing at different ionizing-radiation intensities lie on the corresponding common curves Nit(t) and Qot(t). The Nit(t) common curve is determined by the dispersive nature of the transport of hydrogen ions Н+. The observed deviations from this Nit(t) common curve immediately after the end of ionizing irradiation are due to the transient process of the redistribution of Н+ ions. The Qot(t) common curve is determined by relaxation of the volume charge from a system of levels with energies of 0.3 to 1.0 eV by the mechanism of thermal emission. It is shown that the enhanced low-dose-rate sensitivity (ELDRS) for the MOS structures with a thick base oxide at low intensities is determined by the dispersive character of the transport of hydrogen ions Н+.

Study of the Effect of Radiation Dose Rate on the Stability of Various Organochlorine Pesticides

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Microbial activity in Martian analog soils after ionizing radiation: implications for the preservation of subsurface life on Mars.

At present, the surface of Mars is affected by a set of factors that can prevent the survival of Earth-like life. However, the modern concept of the evolution of the planet assumes the existence more favorable for life climate in the past. If in the past on Mars had formed a biosphere, similar to the one that originated in the early Earth, it is supposed that it is preserved till now in anabiotic state in the bowels of the planet, like microbial communities inhabiting the ancient permafrost of Arctic and Antarctic. In the conditions of modern Martian regolith, this relic life seems to be deprived of the possibility of damage reparation (or these processes occur on a geological time scale), and ionizing radiation should be considered the main factor inhibiting such anabiotic life. In the present study, we studied soil samples, selected in two different extreme habitats of the Earth: ancient permafrost from the Dry Valleys of Antarctica and Xerosol soil from the mountain desert in Morocco, gamma-irradiated with 40 kGy dose at low pressure (1 Torr) and low temperature (−50 °C). Microbial communities inhabiting these samples showed in situ high resistance to the applied effects, retained high number of viable cells, metabolic activity, and high biodiversity. Based on the results, it is assumed that the putative biosphere could be preserved in the dormant state for at least 500 thousand years and 8 million years in the surface layer of Mars regolith and at 5 m depth, respectively, at the current level of ionizing radiation intensity.

Low-dose ionizing radiation limitations to seed germination: Results from a model linking physiological characteristics and developmental-dynamics simulation strategy

There is much uncertainty about the risks of seed germination after repeated or protracted environmental low-dose ionizing radiation exposure. The purpose of this study is to explore the influence mechanism of low-dose ionizing radiation on wheat seed germination using a model linking physiological characteristics and developmental-dynamics simulation. A low-dose ionizing radiation environment simulator was built to investigate wheat (Triticum aestivum L.) seeds germination process and then a kinetic model expressing the relationship between wheat seed germination dynamics and low-dose ionizing radiation intensity variations was developed by experimental data, plant physiology, relevant hypotheses and system dynamics, and sufficiently validated and accredited by computer simulation. Germination percentages were showing no differences in response to different dose rates. However, root and shoot lengths were reduced significantly. Plasma governing equations were set up and the finite element analysis demonstrated H2O, CO2, O2 as well as the seed physiological responses to the low-dose ionizing radiation. The kinetic model was highly valid, and simultaneously the related influence mechanism of low-dose ionizing radiation on wheat seed germination proposed in the modeling process was also adequately verified. Collectively these data demonstrate that low-dose ionizing radiation has an important effect on absorbing water, consuming O2 and releasing CO2, which means the risk for embryo and endosperm development was higher.

Characteristics of aerosol by-products generated from sulfur hexafluoride treatment using ionizing energy

Decomposition of SF6 and its by-products by ionizing radiation were investigated. The SF6 concentration was decreased as the ionizing radiation intensity increased. When the initial concentration of SF6 increased, the removal efficiency of SF6 was decreased. As a result, the ionizing radiation intensity and initial concentration were the influencing factor in the treatment process. The deposited particles and aerosol particles on effluent pipeline and HEPA filters were characterized by scanning electron microscopy (SEM) with the energy dispersion spectrum analysis (EDS), attenuated total reflectance/Fourier transform infrared spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). The amount of aerosol particles in the HEPA filter was influenced by the ionizing radiation intensity. The detected species in the HEPA filter are S-S, SF5, SOF2, SF4, SO2F2, S=O and SOF4 by FTIR-ATR. This means that the SFx compounds formed by ionizing irradiation still existed. When we compared with results of removal characteristics using plasma, the input energy of ionizing radiation process was 3–37 times higher than that of plasma. However, the required energy of ionizing radiation process for 1 g of SF6 removal was 16–160 times lower than the other processes. It is evident that the ionizing radiation process was more efficient process than that of plasma.

Influence mechanism of low-dose ionizing radiation on Escherichia coli DH5α population based on plasma theory and system dynamics simulation

It remains a mystery why the growth rate of bacteria is higher in low-dose ionizing radiation (LDIR) environment than that in normal environment. In this study, a hypothesis composed of environmental selection and competitive exclusion was firstly proposed from observed phenomena, experimental data and microbial ecology. Then a LDIR environment simulator (LDIRES) was built to cultivate a model organism of bacteria, Escherichia coli (E. coli) DH5α, the accurate response of bacterial population to ionizing radiation intensity variation was measured experimentally, and then the precise relative dosage of ionizing radiation E. coli DH5α population received was calculated by finite element analysis based on drift-diffusion equations of plasma. Finally, a highly valid mathematical model expressing the relationship between E. coli DH5α population and LDIR intensity was developed by system dynamics based on hypotheses, experimental data and microbial ecology. Both experiment and simulation results clearly showed that the E. coli DH5α individuals with greater specific growth rate and lower substrate consumption coefficient would adapt and survive in LDIR environment and those without such adaptability were finally eliminated under the combined effects of ionizing radiation selection and competitive exclusion.

Natural Radioactivity of Solid and Liquid Phases from Shale oil and Gas Prospecting in Pomerania

Ionizing radiation intensity data and estimation of equivalent absorbed doses from solid and liquid samples from prospecting shale gas and oil at select sites in Pomerania are presented. Naturally occurring radioactive materials (NORM) are associated with geological formations or fluids and can be enhanced during oil and gas production. They appear in e.g. drilling cuttings, flow-back water, produced water, scale, and sludge. In this study only gamma rays were detected and their intensity was comparable to the background radiation, which is 20.0±4.6 [min -1 ]. The highest value of 27.3 [min -1 ] was detected in solid residue from evaporated flow-back fluid after hydraulic fracturing. The equivalent absorbed dose from this sample was ~ 2 Sv/a, which is lower than the global average dose from 2.4 Sv/a background radiation. In this regard, workers and others in the vicinity of drilling well sites will not be exposed to external or internal ionizing radiation.

Low-energy broad-beam photon shielding data for constituents of concrete.

The ability of concrete to attenuate ionizing radiation intensity is assessed using its linear or mass attenuation coefficient. In this work, the broad‐beam linear and mass attenuation coefficients of different types of soils and cements used for making concrete were measured at different photon energies (60–1333 keV), nearly spanning the diagnostic photon energy range, using a NaI detector. The mass attenuation coefficients of cement decreased from 0.133±0.002 at 60 keV to 0.047±0.003 at 1332.5 keV. For soils, the mass attenuation coefficient of those collected from the beach was the highest, decreasing from 0.176±0.003cm2/g at 60 keV to 0.054±0.001cm2/g at 1332.5 keV. Land soils had the least value, decreasing from 0.124±0.002cm2/g at 60 keV to 0.044±0.003cm2/g at 1332.5 keV. Limestone had smaller mass attenuation coefficients than the cement produced using it. The implication of the above is that for making concrete, beach sand should be preferred as the sand component of the concrete. Models of the form μL=A(E)exp[B(E)ρ] and μm=αln(E)+β are proposed for fitting the linear attenuation coefficient and mass attenuation coefficient data, respectively.PACS numbers: 87.55.N‐; 87.50.cm

Computational evaluation of changes in ionizing radiation dose distribution in tissues caused by EM applicators when external radiation and hyperthermia act simultaneously

Purpose: The presented theoretical study investigates the influence of CFMA-like electromagnetic microstrip applicators (MAs) on ionizing radiation intensity and depth radiation dose distribution (DRDD) in irradiated tissues which are tightly covered with a MA.Methods: It is shown that at relatively low photon energy (<200 keV) the MA does not affect noticeable the profile of the DRDD curve and does not lead to skin overdosing. Nevertheless, it significantly (up to 20–35%) decreases the low energy ionizing radiation intensity. For high energy photons (>1 MeV), on the contrary, the decrease of radiation intensity, caused by the MA, is small (3–10%), but the profile of the DRDD curve, calculated by means of the Monte-Carlo method, is significantly affected.Results: The radiation dose maximum is shifted to the skin, resulting in possible skin overdosing. Radiation absorption characteristics of MA are calculated and compared with published parameters of EM horn and US applicators now in use for external simultaneous radiation and hyperthermia (ESRH) procedures. The MA provides the minor ionizing radiation absorption. Due to it and owing to their conformability with the tissue surface the MAs would not require any additional means or devices to be used for ESRH treatment procedures with any common ionizing radiation equipment.Conclusions: The necessity of development means for decreasing the time of radiation equipment occupation during ESRH procedures is pointed out.

The Reionization History and Early Metal Enrichment Inferred from the Gamma-Ray Burst Rate

Based on the gamma-ray burst (GRB) event rate at redshifts of $4 \leq z \leq 12$, which is assessed by the spectral peak energy-to-luminosity relation recently found by Yonetoku et al., we observationally derive the star formation rate (SFR) for Pop III stars in a high redshift universe. As a result, we find that Pop III stars could form continuously at $4 \leq z \leq 12$. Using the derived Pop III SFR, we attempt to estimate the ultraviolet (UV) photon emission rate at $7 \leq z \leq 12$ in which redshift range no observational information has been hitherto obtained on ionizing radiation intensity. We find that the UV emissivity at $7 \leq z \leq 12$ can make a noticeable contribution to the early reionization. The maximal emissivity is higher than the level required to keep ionizing the intergalactic matter at $7 \leq z \leq 12$. However, if the escape fraction of ionizing photons from Pop III objects is smaller than 10%, then the IGM can be neutralized at some redshift, which may lead to the double reionization. As for the enrichment, the ejection of all metals synthesized in Pop III objects is marginally consistent with the IGM metallicity, although the confinement of metals in Pop III objects can reduce the enrichment significantly.

On the Importance of Local Sources of Radiation in Cosmological Absorption Systems

An upper limit to the importance of local sources of radiation compared to the cosmic background in cosmological absorption systems is derived as a simple consequence of the conservation of surface brightness. The limit depends only on the rate of incidence of the absorbers and the mean free path of the radiation. It is found that on average, the ionizing radiation intensity from local sources in Lyman limit systems at z > 2 must be less than half of the intensity of the cosmic background. In absorbers with column densities much lower than Lyman limit systems, the local source contribution must be negligible. The limit on the ratio of local source to background intensities is then applied to the class of damped Lyα absorption systems with detectable excited C II lines. A cooling rate of the gas in these systems has been measured by Wolfe et al., who assumed that the balancing heating source is photoelectric heating of dust by light at ~1500 Å. The intensity from local star formation at this wavelength in this class of damped Lyα systems is found to be at most ~3 times the background intensity. If the heating source is indeed photoelectric heating of dust, the background created by sources associated with damped Lyα systems can then be estimated from the average cooling rates measured in the absorbers. Current results yield a background intensity higher than previous estimates based on observed galaxy and quasar luminosity functions, although with a large uncertainty. The possibility of other sources of heating, such as shock-heating in a turbulent medium, should be explored.

A Grid of Composite Models for the Simulation of the Emission‐Line Spectra from the Narrow‐Line Regions of Active Galaxies

A grid of composite models for the narrow-line region of active galaxies, which consistently account for both the effect of a photoionizing radiation from the active center and of a shock front, is presented. Theoretical results, calculated with the SUMA code, are given for different values of shock velocities, preshock densities, geometrical thickness of the clouds, and, particularly, for the ionizing radiation intensity in a large range. The input parameters are chosen within the ranges indicated by previous fits of several observed emission-line and continuum spectra from active galaxies. Shock velocities from 100 to 1500 km s-1 and preshock densities from 100 to 1000 cm-3 are considered. The line intensities of the most important ultraviolet, optical, and infrared transitions are obtained and are listed in several tables.

The Low-Column Density Lyα Forest

We develop an analytical method to compute the column density distribution of the Lyα forest in the low-column density limit. We compute the column density distributions for six different cosmological models and found that the standard, COBE-normalized CDM model cannot fit the observations of the Lyα forest at z = 3. The amplitude of the fluctuations in that model has to be lowered by a factor of almost 3 to match observations. However, the currently viable cosmological models like the slightly tilted COBE-normalized CDM+Λ model, the CHDM model with Ων = 0.2, and the low-amplitude standard CDM model are all in agreement with observations for the value of the cosmological baryon density at or higher than the old standard big bang nucleosynthesis value of Ωbh2 = 0.0125 for the currently favored value of the ionizing radiation intensity. With the low value for the baryon density inferred by Rugers & Hogan, the models can only marginally match observations.

Effect of ionizing tritium radiation in hermetically closed air on the removal of condensation nuclei

On the model of hermetically closed, tritium-ionized air of a room, not infiltrated by atmospheric air, i.e., in conditions when aerosol removal is not masked by homogeneous nucleation of condensation nuclei (CN), the processes of CN coagulation, gravitational sedimentation, and electric impaction are studied experimentally in their dependence on ionizing radiation and grounding of the container walls. The CN concentration half-time is found to decrease (even down to one-fifth) as the ionizing radiation intensity is raised from 0 to 719 mCi. In the initial stages of CN removal, coagulation predominates, whereas the subsequent stages are predominantly determined by electric impaction. The influence of those phenomena on the hygienic and sanitary conditions of the air of rooms is discussed.

Bubble chamber detector of weak radioactivity

A bubble chamber detector for very weak radioactivity is described in which boiling frequency gives a measurement of the ionizing radiation intensity. Some preliminary measurements are reported giving indications of the sensitivity of the apparatus to protons and beta and alpha particles.