Effects Of High-energy Radiation Research Articles

Effect of high-energy radiation on the electrical and optical characteristics of bioactive glasses

Effect of high-energy radiation on the electrical and optical characteristics of bioactive glasses

Effect of high energy radiation on electrical properties of synthetic bone materials

AbstractHydroxyapatites have been investigated since past six decades as laser host materials. Because of their important roles in bone and teeth, these have been subjects of recent investigations. Gallium and titanium have great potential for decreasing the depletion of calcium and reducing osteoporosis. The electrical properties and polarity play important roles in regeneration of the bones. We observed growth of grains in selenium‐doped gallium and titanium containing silicate hydroxyapatites. Observed morphology showed non‐facetted microstructures and it helped in achieving larger grains. For the material processed for the period of longer than 70 h, we did not observe any difference in the dielectric constant and resistivity of the selenium‐doped materials. For irradiating the materials, a Cs‐137 γ‐radiation with 5 µm curie dose was used up to 100 h. We observed that the dielectric constant and resistivity at different frequencies ranging from 100 to 100 000 Hz were affected by the high energy radiation. However, bias voltage in the range of 50–1 000 mV did no alter the dielectric constant or resistivity. This indicated that the breakdown of the material did not occur for this bias range.

Aggregation and Charging of Mineral Cloud Particles under High-energy Irradiation

It is known from Earth that ionizing high-energy radiation can lead to ion-induced nucleation of cloud condensation nuclei in the atmosphere. Since the amount of high-energy radiation can vary greatly based on the radiative environment of a host star, understanding the effect of high-energy radiation on cloud particles is critical to understand exoplanet atmospheres. This study aims to explore how high-energy radiation affects the aggregation and charging of mineral cloud particles. We present experiments conducted in an atmosphere chamber on mineral SiO2 particles with diameters of 50 nm. The particles were exposed to gamma radiation in either low-humidity (RH ≈ 20%) or high-humidity (RH > 50%) environments. The aggregation and charging state of the particles were studied with a scanning mobility particle sizer. We find that the single SiO2 particles (N1) cluster to form larger aggregates (N2–N4), and that this aggregation is inhibited by gamma radiation. We find that gamma radiation shifts the charging of the particles to become more negative by increasing the charging state of negatively charged particles. Through an independent t-test, we find that this increase is statistically significant within a 5% significance level for all aggregates in the high-humidity environment and all except the N1 particles in the low-humidity environment. For the positively charged particles, the changes in charging state are not within the 5% significance level. We suggest that the overall effect of gamma radiation could favor the formation of a high number of small particles over a lower number of larger particles.

High-Energy Radiation Effects on Silicon NPN Bipolar Transistor Electrical Performance: A Study with 1 MeV Proton Irradiation.

This study investigates the degradation of the silicon NPN transistor's emitter-base junction, specifically the 2N2219A model, under both forward and reverse polarization. We examine the current-voltage characteristics under the influence of 1 MeV proton irradiation at various fluencies, which are 5.3×108,5.3×1010,5×1011,5×1012, and 5×1013 protons/cm², all conducted at 307 K. The experimental findings elucidate a pronounced dependency of diode parameters, including the reverse saturation current, series resistance, and the non-idealist factor, on the incident proton flow. This observation underscores that proton-induced degradation is primarily driven by displacement damage, while recorded degradation is predominantly attributed to the generation of defects and interfacial traps within the transistor resulting from exposure to high-energy radiation. Our findings indicate that the effects of irradiation align more closely with the compensation phenomenon in doping rather than its reinforcement.

Evolution of X-Ray Activity in

Measuring the evolution of X-ray emission from pre-main-sequence (PMS) stars gives insight into two issues: the response of magnetic dynamo processes to changes in the interior structure, and the effects of high-energy radiation on protoplanetary disks and primordial planetary atmospheres. We present a sample of 6003 stars with ages 7–25 Myr in 10 nearby open clusters from Chandra X-ray and Gaia-EDR3 surveys. Combined with previous results in large samples of younger (≲5 Myr) stars in MYStIX and SFiNCs star-forming regions, mass-stratified activity-age relations are derived for the early phases of stellar evolution. X-ray luminosity (L X ) is constant during the first few Myr, possibly due to the presence of extended X-ray coronas insensitive to temporal changes in stellar size. L X then decays during the 7–25 Myr period, more rapidly as stellar mass increases. This decay is interpreted as decreasing efficiency of the α 2 dynamo as radiative cores grow and a solar-type αΩ dynamo emerges. For more massive 3.5–7 M ⊙ fully radiative stars, the X-ray emission plummets—indicating the lack of an effective magnetic dynamo. The findings provide improved measurements of high-energy radiation effects on circumstellar material, first for the protoplanetary disk and then for the atmospheres of young planets. The observed X-ray luminosities can be so high that an inner Earth-mass rocky, unmagnetized planet around a solar-mass PMS star might lose its primary and secondary atmospheres within a few (several) million years. PMS X-ray emission may thus have a significant impact on the evolution of early-planetary atmospheres and the conditions promoting the rise of habitability.

The Posttransit Tail of WASP-107b Observed at 10830 Å

Abstract Understanding the effects of high-energy radiation and stellar winds on planetary atmospheres is vital for explaining the observed properties of close-in exoplanets. Observations of transiting exoplanets in the triplet of metastable helium lines at 10830 Å allow extended atmospheres and escape processes to be studied for individual planets. We observed one transit of WASP-107b with NIRSPEC on Keck at 10830 Å. Our observations, for the first time, had significant posttransit phase coverage, and we detected excess absorption for over an hour after fourth contact. The data can be explained by a comet-like tail extending out to ∼7 planet radii, which corresponds to roughly twice the Roche lobe radius of the planet. Planetary tails are expected based on three-dimensional simulations of escaping exoplanet atmospheres, particularly those including the interaction between the escaped material and strong stellar winds, and have been previously observed at 10830 Å in at least one other exoplanet. With both the largest midtransit absorption signal and the most extended tail observed at 10830 Å, WASP-107b remains a keystone exoplanet for atmospheric escape studies.

Evidence for the protection of N-heterocycles from gamma radiation by Mars analogue minerals

Organic compounds have been delivered to the surface of Mars via meteorites, comets and interplanetary dust particles for billions of years. Determining the effects of high energy radiation and galactic cosmic radiation (GCR) on these organic compounds is critical for understanding the potential for the preservation of organic molecules associated with past or present life, and where to look for possible chemical bio- signatures during future Mars missions. Understanding how these effects are attenuated by the mineral matrix and the depth at which they are buried have been challenging to determine in situ on Mars. There have been very few experimental studies on the survival of organic compounds under radiation from a gamma source under realistic conditions, and their interpretation until now has been difficult due to the lack of data for actual radiation levels on Mars. Using the in-situ data obtained by the MSL/RAD instrument to anchor the dose calculations, here we show that the N-heterocycles purine and uracil, crucial components of biochemical processes in extant living systems, mixed with calcite, anhydrite, and kaolinite as Mars analogue minerals can survive the effects of radiation with a dose corresponding to ~500,000 years on the Martian surface. The extent of survival varied not only with the nature of the organic compound, but its depth from the surface. These results provide new experimental data for the degree of protection offered by the regolith, in conjunction with minerals, for organic compounds that may be present on Mars.

Effect of End-of-production High-energy Radiation on Nutritional Quality of Indoor-grown Red-leaf Lettuce

Numerous studies have evaluated the effect of high-energy radiation as means to increase nutritional quality of lettuce (Lactuca sativa). However, most research has focused on providing constant radiation quality or quantity throughout the production cycle, which typically results in yield reductions or increases in production costs. End-of-production (EOP) radiation is a cost-effective, preharvest practice that can allow growers to manipulate product quality and thus increase market value of lettuce without negatively affecting plant growth. The objective of this study was to quantify and compare growth and accumulation of secondary metabolites from ‘Rouxaï RZ’ and ‘Codex RZ’ red-leaf lettuce grown indoors and exposed to different strategies of EOP high-energy radiation. Plants were grown for 24 days under an average daily light integral (DLI) of 15.8 mol·m‒2·d‒1 (220 µmol·m‒2·s‒1 for 20 h·d−1) using red:blue light-emitting diode (LED) lamps. Four days before harvest (36 days after sowing), plants were exposed to one of three EOP treatments added to red:blue LEDs: 1) ultraviolet-A (EOP-ultraviolet); 2) high blue (EOP-B); or 3) high-intensity (EOP-H) radiation. A fourth treatment was included as a control, with no EOP. Except for EOP-H, all treatments provided a DLI of 15.8 mol·m‒2·d‒1; EOP-H provided a DLI of 31.7 mol·m‒2·d‒1. No treatment differences were measured for shoot fresh weight (FW) of ‘Rouxaï RZ’ but shoot FW of ‘Codex RZ’ was negatively affected by EOP radiation, indicating potential changes in lettuce yield from applying EOP high-energy radiation during active plant growth. In general, EOP treatments did not affect total phenolic content and total carotenoid concentration of plants, but anthocyanin content and antioxidant capacity were positively influenced by EOP-B and EOP-H, whereas EOP-ultraviolet resulted in similar nutritional quality to control. Findings from this study indicate that EOP high-energy radiation, especially EOP-B, has significant potential to improve the nutritional quality of red-leaf lettuce grown in controlled environments.

Radiation effects, photoluminescence and radioluminescence of Eu-doped (Y0.7Gd0.3)2O3 nanoparticles with various sizes

(Y1-xLnx)2O3 oxides (Ln = Y, Gd, Lu) doped with Eu3+ ions are widely used as commercialized scintillators in medical and industrial scanning applications, with high performance and attractive properties. In this work, effects of high-energy radiation on luminescence properties of (Y1-xGdx)2O3: Eu3+ powders with different particle sizes in the nanometric range are analyzed. Powders were prepared by polymer complex solution route, followed by annealing. Nanoparticles were obtained with an average size between 20 and 120 nm according to annealing conditions (time and temperature). Samples were exposed to gamma-irradiation (doses up to 4 MGy) on a commercial gamma-irradiation plant. The effect of irradiation on different nanoparticle size is followed by XRD, TEM and monitoring their luminescence properties. No change was observed in structure, morphology and steady-state emission. On the opposite after irradiation, excited-state lifetimes and quantum efficiency values are particle size dependent.

Gamma ray radiation effect on Bi2WO6 photocatalyst

The development of Bi2WO6-based materials has become one of research hotspots due to the increasing demands on high-efficient photocatalyst responding to visible light. In this work, the effect of high energy radiation (γ-ray) on the structure and the photocatalytic activity of Bi2WO6 nanocrystals was first studied. No morphological change of Bi2WO6 nanocrystals was observed by SEM under γ-ray radiation. However, the XRD spectra of the irradiated Bi2WO6 nanocrystals showed the characteristic 2θ of (113) plane shifts slightly from 28.37° to 28.45° with the increase of the absorbed dose, confirming the change in the crystal structure of Bi2WO6. The XPS results proved the crystal structure change was originated from the generation of oxygen vacancy defects under high-dose radiation. The photocatalytic activity of Bi2WO6 on the decomposition of methylene blue (MB) in water under visible light increases gradually with the increase of absorbed dose. Moreover, the improved photocatalytic performance of the irradiated Bi2WO6 nanocrystals remained after three cycles of photocatalysis, indicating a good stability of the created oxygen vacancy defects. This work gives a new simple way to improve photocatalytic performance of Bi2WO6 through creating oxygen vacancy defects in the crystal structure by γ-ray radiation.

Damage and recovery of fiber Bragg grating under radiation environment**Project supported by the Project for the State Key Laboratory of Optoelectronic Materials and Technologies of China (Grant No. 09010-32031708) and the Project for Zhuhai Key Laboratory of Center for Space Technology of China (Grant No. 71000-42080001).

To develop the application of fiber Bragg gratings as temperature and strain sensors in space environments, it is necessary to understand the effect of high-energy radiation on the performance of the fiber Bragg grating. We performed an experiment involving Co60-γ ionizing irradiation with a total dose of 1.01 × 106 rad on two Ge-doped single-mode fiber Bragg gratings with central wavelengths of 825 and 835 nm, respectively. We found that, with the increase of radiation dose, the redshift of the peak wavelength of the reflection spectrum of the fiber Bragg gratings indicated the increase of the refractive index and the number of color centers. After irradiation, the refractive index decreased with the decreasing number of color centers. We analyzed the influence of ionizing irradiation on the transmission performance of the fiber Bragg gratings using a color-center model, which explained the experimental results. The proposed model was used to determine the creation rate and annihilation rates of the color center, which are foundational data for using the fiber Bragg gratings in space applications.

Electron-beam radiation effects on the structure and properties of polypropylene at low dose rates

While the high-energy radiation effects on polypropylene, which are crucial for the cable industry for nuclear power plants, have been thoroughly studied, the property changes of PP at low-dose-rate electron-beam irradiation are far from elucidated. Herein, the influence of electron-beam irradiation on the structure and properties of PP was examined. The static EB irradiation conditions were 1.2 MeV at a low dose rate of 20 kGy/h to achieve absorbed doses ranging from 45, to 60, 100, and 200 kGy. The molecular structure was first evaluated by measuring the carboxyl index and the relative radical concentrations via Fourier transform infrared spectroscopy and electron spin resonance, respectively. Mechanical, differential scanning colorimetric, and rheological tests were carried out to further investigate the changes in the properties (tensile, crystalizing, and viscoelastic properties) of irradiated PP, which showed good agreement with the structural analysis results. We found that radio-oxidative degradation (chain scission) was predominant, which can be due to the low dose rate facilitating oxygen diffusion into the PP matrix during electron-beam irradiation.

Effects of high energy radiation and thermo-chemical environments on polyetherimide composites: futuristic approach to nuclear waste storage

Effects of high energy radiation and thermo-chemical environments on polyetherimide composites: futuristic approach to nuclear waste storage

Effects of high energy radiation and thermo-chemical environments on polyetherimide composites: futuristic approach to nuclear waste storage

This research highlights the effect of radiation, chemical and thermal environments on mechanical and thermal properties of polyetherimide (PEI) composites. The tests are conducted on specimens made from PEI and PEI reinforced with modified Carbon Nano Fibre (CNF). The specimens are subjected to gamma radiation doses of 5 MGy, which is equivalent to the cumulative dose of radiation from spent nuclear fuel until the end of complete radioactivity. The exposed samples are further subjected to highly corrosive and thermal environments. Studies under transmission electron microscopy reveal that there is a uniform dispersion of modified CNF in PEI. Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA) indicate that there are no significant changes in thermal properties of PEI and PEI composite when exposed to aggressive environments. It is observed that there is a marginal loss in the tensile strength of polymeric samples when exposed to gamma radiation and thermal environments. PEI samples when subjected to alkaline corrosive environments show significant loss in the tensile strength. There is a significant decrease in the molecular weight of PEI under alkaline corrosive environments as seen from Gel Permeable Chromatography (GPC).

The effects of high energy radiation on the vestibular and immune function in rats (693.22)

The objective of the project is to study radiation effects on the vestibular and immune systems in rats. It is proposed that high energy radiation will compromise vestibular/balance system and immune function since nasopharyngeal cancer patients experience post‐irradiation vertigo and whole body radiation therapy causes immune suppression. However, the underlying mechanisms are not fully understood.Sprague‐Dawley rats were exposed to different doses of either unilateral cranial using 6 MeV electron beam (0 to 60Gy) or whole body using 18 MeV electron beam (0 to 10 Gy). For vestibular study, seven days post irradiation, single unit recording of vestibular afferent activity was performed. A total of 309 horizontal semicircular canal afferents’ responses to sinusoidal earth‐horizontal rotations (~1Hz) were analyzed. For immune function study, total RNAs were extracted from immune organs such as thymus and spleen. The genes involved in Stress and Toxicity PathwayFinder were examined using RT2 ProfilerTM PCR Array.Preliminary analysis shows that electron irradiation caused significant decreases in the gains of the irregular horizontal semicircular canal afferents. The gene expression profiles indicated significant changes in oxidative stress, DNA damage and repair as well as apoptosis related genes.In conclusion, these results indicate that irradiation exposure induces specific functional deficiency of the vestibular and immune system in rats.Grant Funding Source: Supported by NASA MSI EPSCoR (NNX12AK85A and NNX13AB31A), NIH R01DC012060 (HZ), NIH R01DC008585 (WZ)

ROS enhancement by silicon nanoparticles in X-ray irradiated aqueous suspensions and in glioma C6 cells

The capability of silicon nanoparticles to increase the yield of reactive species upon 4 MeV X-ray irradiation of aqueous suspensions and C6 glioma cell cultures was investigated. ROS generation was detected and quantified using several specific probes. The particles were characterized by FTIR, XPS, TEM, DLS, luminescence, and adsorption spec- troscopy before and after irradiation to evaluate the effect of high energy radiation on their structure. The total concentration of O2 •- /HO2 • ,H O • , and H2O2 generated upon 4-MeV X-ray irradiation of 6.4 lM silicon nanoparticle aqueous suspensions were on the order of 10 lM per Gy, ten times higher than that obtained in similar experiments but in the absence of particles. Cytotoxic 1 O2 was generated only in irradi- ation experiments containing the particles. The particle surface became oxidized to SiO2 and the luminescence yield reduced with the irradiation dose. Changes in the surface morphology did not affect, within the experi- mental error, the yields of ROS generated per Gy. X-ray irradiation of glioma C6 cell cultures with incorporated silicon nanoparticles showed a marked production of ROS proportional to the radiation dose received. In the absence of nanoparticles, the cells showed no irradia- tion-enhanced ROS generation. The obtained results indicate that silicon nanoparticles of\5 nm size have the potential to be used as radiosensitizers for improv- ing the outcomes of cancer radiotherapy. Their capa- bility of producing 1 O2 upon X-ray irradiation opens

A study of gamma-irradiated polyethylenes by temperature modulated differential scanning calorimetry

Various polyethylenes (PEs) and the effects of high-energy radiation on their structures were widely studied in the past using conventional Differential Scanning Calorimetry (DSC) measurements. In this work, we used the Temperature Modulated Differential Scanning Calorimetry (TMDSC) technique in order to obtain more information about the influence of the initial structural differences and gamma radiation on the evolution in structure and thermal properties of different polyethylenes. For this reason, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) samples were exposed to gamma radiation, in air, to a wide range of absorbed doses (up to 2400kGy). The separation of the total heat flow TMDSC signal into a reversing and non-reversing part enabled us to observe the low-temperature enthalpy relaxation (related to the existence of the “rigid amorphous phase”) and recrystallisation processes, as well as to follow their radiation-induced evolution and/or that of melting in a more revealing manner compared to the case of the conventional DSC. Consequently, our results indicate that TMDSC could improve the understanding of radiation-induced effects in polymers.

The Effects of High Energy Radiation on the Tensile Properties of Rubber Toughened Nanocomposites

Composites based on high density polyethylene (HDPE), ethylene propylene diene monomer (EPDM) and Organically Modified Montmorillonite (OMMT) clays were made by melt compounding followed by compression molding. Mechanical properties, X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) were used to characterize the nanocomposites. The addition of clay, compatibilizer agent, Maleic Anhydride Polyethylene (MAPE) and irradiation technique, High Energy Electron Beam (EB) considerably improved the properties of nanocomposites. Tensile Strength and Modulus (MPa) were found to increase significantly with increasing clay content and decreasing as the clay content exceeds 4 vol%. The largest improvement in nanocomposite tensile properties occurred at clay loading of 4 vol% (2-8 vol%) with irradiation technique. The d spacings of the clay in nanocomposites were monitored using XRD and the extent of delamination was examined by TEM. TEM photomicrographs illustrated the intercalated and exfoliated structures of the nanocomposites with OMMT, MAPE and irradiation process.

Effects of High Energy Radiation on Mechanical Properties of PP/EPDM Nanocomposite

Nanocomposites are the materials that are created by introducing nanoparticulates that always referred to as filler into the matrix. Blends of polypropylene (PP)/ethylene propylene diene monomer (EPDM)/Montmorillonite (MMT) were treated by compatibilizer MAPP and irradiation of electron beam. The effects on mechanical properties for both samples were compared with the untreated nanocomposites. Because each samples used different portion of clay loading, the effects of clay loading on mechanical properties is also observed. The sample is characterized by using Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD), tensile test and impact test.

Network characteristics of hydrogenated nitrile butadiene rubber networks obtained by radiation crosslinking by electron beam

The effects of high-energy radiation on hydrogenated nitrile butadiene rubber (HNBR) copolymer structure and properties were studied. Characterization by FTIR spectroscopy, swelling and mechanical measurements of irradiated and un-irradiated sample permit us to correlate the change in structure with properties. The modifications obtained are dependent on the radiation dose of the incident electron beam. FTIR spectroscopy in absorption mode shows that irradiation of HNBR first induces trans-vinylene bond formation and secondly small amounts of carbonyl (C O) groups. Moreover, more significant changes were observed with swelling method and mechanical behaviour showing the effect of crosslinking on the elastomer.