Radiation-induced Disorder Research Articles

Analysis of Low Signal-to-Noise Atomic Resolution Spectroscopy of Radiation-Induced Sublattice Disorder in Ferritic Superalloys

Analysis of Low Signal-to-Noise Atomic Resolution Spectroscopy of Radiation-Induced Sublattice Disorder in Ferritic Superalloys

Quantum Emitter Formation Dynamics and Probing of Radiation-Induced Atomic Disorder in Silicon

Quantum Emitter Formation Dynamics and Probing of Radiation-Induced Atomic Disorder in Silicon

Surface antibacterial activity of multi-walled carbon nanotubes with an intrinsic and radiation-induced disorder

Surface antibacterial activity of multi-walled carbon nanotubes with an intrinsic and radiation-induced disorder

Reduction of bright exciton lifetimes by radiation-induced disorder

Quantum-radiative decay is a fundamental process in many optoelectronic systems such as laser diodes and solar cells. The bright exciton lifetime is a critical factor in determining the performance of these systems. Motivated by the ever-increasing need for laser systems in space and nuclear applications, we develop a many-particle approach to predict the radiative lifetime under harsh radiation environments. Using GaAs as a model system, we find that radiation-induced band tailing reduces the bright exciton lifetime. This result shows that the efficiency of radiative recombination, in addition to nonradiative recombination, can be affected by ionization radiation. Our approach enables a detailed understanding of the interplay between correlation, localization, and radiation that affect the performance of gain media.

Dominating migration barrier for intrinsic defects in gallium oxide: Dose-rate effect measurements

Ion bombardment provides an opportunity to study basic properties of intrinsic defects in materials since the radiation-induced disorder accumulation depends on the balance between defect generation and migration rates. In particular, variation of such parameters as irradiation temperature and ion flux, known in the literature as dose-rate effect, interconnects the macroscopically measured lattice disorder with the migration barrier of the dominating defects. In this work, we measured the dose-rate effect in monoclinic gallium oxide (β-Ga2O3) and extracted its activation energy of 0.8 ± 0.1 eV in the range of 25–250 °C. Taking into account that the measurements were performed in the Ga-sublattice and considering 0.8 ± 0.1 eV in the context of theoretical data, we interpreted it as the migration barrier for Ga vacancies in β-Ga2O3, limiting the process. Additionally, we observed and took into account an interesting form of the lattice relaxation due to radiation-induced disorder buildup, interpreted in terms of the compressive strain accumulation, potentially trigging phase transitions in Ga2O3 lattice.

Effects of phycocyanin on pulmonary and gut microbiota in a radiation-induced pulmonary fibrosis model

ObjectiveRadiation pneumonia and fibrosis are major clinical complications of radiotherapy for thoracic tumor patients, and may significantly reduce survival and quality of life. At present, no safe and effective radiation protection measures have been approved for clinical use. Phycocyanin, a protein responsible for photosynthesis from Spirulina, has been shown to have a variety of biological activities and to be beneficial for a variety of diseases, including pulmonary fibrosis. However, the preventive and protective effects of phycocyanin on radiation-induced pulmonary fibrosis have not been studied. DesignX-ray single dose irradiation was used on the chest of mice to prepare a mouse model of pulmonary fibrosis, from which the effect of phycocyanin on pulmonary histopathologic change, pulmonary fibrosis, the microbiota in lung and gut, LPS, TNF-α, and IL-6 at different time after irradiation were evaluated. ResultsPhycocyanin alleviated the radiation-induced lung injury and reduced the level of inflammatory factors. Thorax irradiation led to the disorder in microbiota of the lung and gut. The variation trend of the diversity of the two tissues was opposite, but that of the microbiota composition was similar. The phycocyanin intervention regulated the composition of the lung and gut microbiota, transformed them into normal state, and reduced the level of LPS, which significantly reduced the abundance of inflammation-related bacteria, and increased the abundance of probiotics that produce short-chain fatty acids. ConclusionPhycocyanin could regulate the radiation-induced disorder in lung and gut microbiota of mice, and reduce the radiation-induced lung inflammation and fibrosis.

Level of Cyclin D1 protein in peripheral blood lymphocytes of Chornobyl clean-up workers in remote period after radiation exposure

Aim: to assess changes of products of Cyclin D1 protein in lymphocytes of peripheral blood of Chernobyl clean-up workers as remote results of the action of ionizing irradiation. Methods: there were examined 120 Chernobyl clean-up workers in the remote period after radiation exposure and 45 persons of the control group. For assessing mitogen-induced levels of Cyclin D1, the micro-method of cultivating erythrocytes of whole blood was used. The quantitative assessment of the spontaneous and mitogen-induced levels of Cyclin D1 in lymphocytes of peripheral blood (PB) was realized using the reagents FITC Mouse Anti-Human Cyclin D1 Antibody Set (BD, USA) by the method of flow cytometry.Research results: there was determined the dose-dependent increase of the spontaneous level of Cyclin D1 in PB lymphocytes of Chornobyl clean-up workers. High values of the parameter were established in the subgroup of Chornobyl clean-up workers, irradiated in the diapason of doses as 500-1000 mSv. Maximal values of Cyclin D1 level in PB lymphocytes were observed in Chornobyl clean-up workers at exacerbation of the bronchial-pulmonary pathology, bronchial asthma in anamnesis and in reconvalescents of acute radiation sickness with the radiation doses D ≥ 500 mSv. After mitogen stimulation of lymphocytes, there was noted the decrease of Cyclin D1 level in the group of Chornobyl clean-up workers and the increase in persons of the control group.Conclusions: the research revealed the differences in products of Cyclin D1 in PB lymphocytes of Chornobyl clean-up workers and persons of the control group. The revealed changes of the spontaneous and mitogen-induced levels of Cyclin D1 in PB lymphocytes of Chornobyl clean-up workers with the somatic pathology reflect disorders in regulation processes of proliferation and cellular cycle. The obtained data add ideas about mechanisms of the radiation-induced disorder of the cellular cycle that may be a manifestation of genome instability and become a trigger factor of carcinogenesis in the remote period after radiation exposure

Effects of polysaccharide from the fruiting bodies of Auricularia auricular on glucose metabolism in 60Co-γ-radiated mice

Radiation is known to be associated with pathology of various human diseases. This study has focused on the effect of radiation on glucose homeostasis with regard to metabolic function of liver and pancreas and the effect of polysaccharide from the fruiting bodies of Auricularia auricular (SNAAP) on glucose metabolism. The 60Co-γ-radiated mice displayed destroyed redox equilibrium, accompanied by increased blood glucose accumulation, decreased insulin and hepatic glycogen contents, impaired blood glucose tolerance ability, abnormal changes in activities of glucose metabolism-related enzymes and damaged hepatic and pancreatic function, while SNAAP can restore the disordered glucose metabolism to some extent. Increased phosphorylation of JNK and FoxO1, reduced phosphorylation of Akt and GSK-3β and increased expression of PEPCK, G6Pase and GYS2 in the liver as well as the decreased expression of PDX1, GLUT2 and IRS1 in the pancreas of radiated mice were recovered after treated with SNAAP, leading to an improved gluconeogenesis and glycogen synthesis. These findings clearly indicate that SNAAP has significant potency in radiation-induced glucose metabolism disorder through modulating the JNK pathway in the liver as well as the PDX1/GLUT2 in the pancreas.

Gamma-Radiation-Induced Endoplasmic Reticulum Stress and Downregulation of WFS1, Nectin 3, and Sostdc1 Gene Expression in Mice Hippocampus.

Introduction:Neurogenesis mainly occurs in the hippocampus that is sensitive to radiation. More histological changes are reported at higher doses of radiation, while low dose radiation causes cognitive dysfunction in adult mammals. In the present study, we tried to correlate the Endoplasmic Reticulum (ER) stress-mediated hippocampus dysfunction after whole-body gamma radiation of mice.Methods:Mice were exposed to a series of gamma radiations, followed by isolation of hippocampus. To elucidate the gene expression profile, qPCR was performed for ER stress markers CHOP, BiP, and hippocampal specific genes WFS1, Nectin 3, and Sostdc 1 on the isolated hippocampus. Expression of CHOP and ERK½ were analyzed by western blot on exposure to gamma radiation.Results:qPCR results showed a significant increase in the expression of ER stress-specific genes CHOP, BiP, and decrease in hippocampal specific genes WFS1, Nectin3, and Sostdc1. Western blot study suggests a significant increase in ER stress proteins like CHOP and ERK½ expression.Conclusion:Exposure to gamma radiation significantly increased the expression of ER-stress genes, suggesting that ER stress plays a major role in inducing radiation mediated dysfunction of the hippocampus. Also, significant downregulation of WFS1, Nectin3, and Sostdc1 genes suggests radiation mediated effect of hippocampal CA 1, CA 2, and CA 3 regions. A further significant increase of ERK½ shows involvement of the ERK pathway in mediating radiation-induced ER stress dysfunction in mice hippocampus. The present findings may lead to the identification of ER stress as a new marker to study radiation-induced neurodegenerative disorder.

Radiation-induced disorder in compressed lanthanide zirconates.

The effects of swift heavy ion irradiation-induced disordering on the behavior of lanthanide zirconate compounds (Ln2Zr2O7 where Ln = Sm, Er, or Nd) at high pressures are investigated. After irradiation with 2.2 GeV 197Au ions, the initial ordered pyrochlore structure (Fd3[combining macron]m) transformed to a defect-fluorite structure (Fm3[combining macron]m) in Sm2Zr2O7 and Nd2Zr2O7. For irradiated Er2Zr2O7, which has a defect-fluorite structure, ion irradiation induces local disordering by introducing Frenkel defects despite retention of the initial structure. When subjected to high pressures (>29 GPa) in the absence of irradiation, all of these compounds transform to a cotunnite-like (Pnma) phase, followed by sluggish amorphization with further compression. However, if these compounds are irradiated prior to compression, the high pressure cotunnite-like phase is not formed. Rather, they transform directly from their post-irradiation defect-fluorite structure to an amorphous structure upon compression (>25 GPa). Defects and disordering induced by swift heavy ion irradiation alter the transformation pathways by raising the energetic barriers for the transformation to the high pressure cotunnite-like phase, rendering it inaccessible. As a result, the high pressure stability field of the amorphous phase is expanded to lower pressures when irradiation is coupled with compression. The responses of materials in the lanthanide zirconate system to irradiation and compression, both individually and in tandem, are strongly influenced by the specific lanthanide composition, which governs the defect energetics at extreme conditions.

In situ characterization of irradiation-induced microstructural evolution in urania single crystals at 773 K

Implantations with low-energy ions (Xe, La) on UO2 single crystals at 773 K were performed to investigate the role played by both the radiation damage and the incorporation of foreign elements on the matrix destabilisation. The radiation damage was monitored by both in situ RBS-C and in situ TEM during ion irradiation experiments performed at 773 K. RBS-C data shows a similar regular increase of the radiation-induced disorder in crystals for both Xe and La ions followed by a saturation plateau at about 3–4 dpa. An unexpected difference of the value of the saturation plateaus is observed, with a higher value recorded for Xe-irradiated crystals. In situ TEM images show the apparition and evolution of several defects as a function of the ion dose up to 40 dpa, irrespective of the nature of the bombarding ion: ‘black dots’ defects, dislocation loops and lines, and finally a dislocation network at high dpa. Nanometre-sized gas bubbles were observed at 773 K for the Xe-implanted crystal for doses larger than 3 dpa. Neither precipitate nor cavity were observed on La-implanted crystals. The difference in the saturation plateau as seen by RBS-C can be ascribed to the formation of the Xe aggregates that lead to an increase of the dechannelling yield.

Radiation-induced temporo-mandibular joint disorder in post-radiotherapy nasopharyngeal carcinoma patients: assessment and treatment.

Nasopharyngeal carcinoma (NPC) is endemic in southern China, and its incidence in Hong Kong is relatively high. Radiotherapy is the mainstay treatment for NPC due to its relatively high radiosensitivity and deep‐seated anatomical position, which is not readily accessible by surgery. Although the technique of radiotherapy in NPC has been advancing and offers promising treatment outcome, complications around the irradiation areas are inevitable and the quality of life of the post‐radiotherapy patients is often compromised. Trismus, which is defined as the restricted mouth opening or jaw movement due to the disorder of temporo‐mandibular joint (TMJ), is one of the possible late complications for radiotherapy of NPC and is found in 5–17% of the post‐radiotherapy (post‐RT) patients. Trismus at early stage may only affect the speech, but in severe cases nutritional intake and oral hygiene condition may deteriorate seriously. This article reviewed the possible causes of radiation‐induced TMJ damage, the various assessments including imaging modalities and possible treatments. The conclusion is that the availability of simple, yet effective examinations for trismus is essential for delaying the progression and restoring TMJ functions. Although there is no absolutely effective treatment for trismus, many supportive, restorative and palliative management are possible under different clinical situations.

Radiation-induced disorder of a protein crystal

Radiation-induced disorder of a protein crystal

Factors affecting the Nd3+ (REE3+) luminescence of minerals

In this paper, possibilities and limits of the application of REE3+ luminescence (especially the Nd3+ 4F3/2 → 4I9/2 emission) as structural probe are evaluated. Important factors controlling the Nd3+ luminescence signal are discussed, including effects of the crystal-field, crystal orientation, structural state, and temperature. Particular attention was paid to the study of the accessory minerals zircon (ZrSiO4), xenotime–(Y) (YPO4), monazite–(Ce) (CePO4) and their synthetic analogues. Based on these examples we review in short that (1) REE3+ luminescence can be used as non-destructive phase identification method, (2) the intensities of certain luminescence bands are strongly influenced by crystal orientation effects, and (3) increased widths of REE3+-related emission bands are a strong indicator for structural disorder. We discuss the potential of luminescence spectroscopy, complementary to Raman spectroscopy, for the quantitative estimation of chemical (and potentially also radiation-induced) disorder. For the latter, emissions of Nd3+-related centres are found to be promising candidates.

Radiation interaction with tilt grain boundaries in β-SiC

Interaction between grain boundaries and radiation is studied in 3C-SiC by conducting molecular dynamics cascade simulations on bicrystal samples with different misorientation angles. The damage in the in-grain regions was found to be unaffected by the grain boundary type and is comparable to damage in single crystal SiC. Radiation-induced chemical disorder in the grain boundary regions is quantified using the homonuclear to heteronuclear bond ratio (χ). We found that χ increases nearly monotonically with the misorientation angle, which behavior has been attributed to the decreasing distance between the grain boundary dislocation cores with an increasing misorientation angle. The change in the chemical disorder due to irradiation was found to be independent of the type of the grain boundary.

LINAC-radiosurgery for nonsecreting pituitary adenomas

Stereotactic linear accelerator-based radiosurgery (LINAC-RS) is increasingly used for microsurgically inaccessible or recurrent pituitary adenomas. This single-center study evaluates the long-term follow-up after LINAC-RS of nonsecreting pituitary adenomas (NSA). Between 1992 and August 2008, 65 patients with NSA were treated. Patient treatment and follow-up were conducted according to a prospective protocol. Indications for LINAC-RS were (1) tumor recurrence or (2) residual tumor. Three patients were treated primarily. For analysis of prognostic factors, patients were grouped according to epidemiological or treatment-associated characteristics. A total of 61 patients with a follow-up ≥ 12 months (median 83 months, range 15-186 months, longest follow-up of published radiosurgery series) were evaluated with regard to their clinical, radiological, and endocrinological course. The median tumor volume was 3.5 ml (± 4.3 ml, range 0.3-17.3 ml) treated with a median surface and maximum dose of 13.0 Gy and 29.7 Gy, respectively. Local tumor control was achieved in 98%. One patient died of unrelated cause after 36 months and 1 patient developed a radiation-induced seizure disorder. Visual complications did not occur. In 37 of 41 patients (90.2%), pituitary function remained stable. Maximum dose to the pituitary ≤ 16 Gy and female gender were positive prognostic factors for the preservation of pituitary function. LINAC-RS is a minimally invasive, safe, and effective treatment for recurrent NSA or microsurgically inaccessible residual tumor. LINAC-RS yielded a high rate of local long-term tumor control with a small number of radiation-induced side effects.

Single and hypofractionated stereotactic radiotherapy with CyberKnife for craniopharyngioma

Craniopharyngiomas are slow-growing tumors found in the suprasellar region, with especially high incidence in Japanese children. Due to the location, proximity and adhesiveness of the tumor to adjacent critical structures, these tumors remain a significant clinical challenge. The purpose of this study was to evaluate the clinical outcome of single and hypofractionated stereotactic radiotherapy (SRT) with CyberKnife for craniopharyngioma. Forty-three patients (21 men and 22 women; median age 44 years; range 3-85 years) were treated at two institutions. Three cases were treated in a single fraction to a marginal dose of 13-16 Gy. The other 40 cases were treated in 2-5 fractions to a marginal dose of 13-25 Gy. Tumor volumes ranged from 0.09 to 20.8 cm(3) (median 2.0 cm(3)). Toxicities were evaluated with the Common Terminology Criteria for Adverse Events version 4.0. The median follow-up period was 40 months (range 12-92 months). The 3-year overall survival and local control rates were 100 and 85%, respectively. In-field cyst enlargement was observed in 9 patients. These tumors had significantly larger volumes (mean 6.9 cm(3); 95% confidence interval, CI, 2.8-10.9 cm(3)) than the 34 controlled tumors (2.9 cm(3); CI 1.5-4.3 cm(3)) (P = 0.02). Out-field tumor regrowth was observed in 4 patients. No radiation-induced symptomatic visual disorder or brain necrosis was observed. Hypopituitarism was observed in only 1 patient. Single and hypofractionated SRT using CyberKnife produced high tumor control rates with minimal complications. Hypofractionated SRT may be useful for protecting the visual nerve and neuroendocrine function, especially for tumors located near the optic pathways and for large tumors.

Radiation-induced Chemical Disorder in Covalent Materials

ABSTRACTChemical disorder in ion-irradiated SiC and GaN has been examined by means of transmission electron microscopy. Radial distribution functions obtained by a quantitative analysis of electron diffraction intensities revealed that homonuclear bonds, which do not exist in the crystalline state, are formed in both ion-irradiated specimens. The origin of the homonuclear bonds is quite different between SiC and GaN. The constitute elements mix on the atomic-scale in amorphous SiC, while phase separation induced by irradiation is attributed to the formation of self-bonded Ga atomic pairs in amorphous/nanocrystalline GaN.

Inductive Potential of Recombinant Human Granulocyte Colony-Stimulating Factor to Mature Neutrophils from X-Irradiated Human Peripheral Blood Hematopoietic Progenitor Cells

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) has been used for treatment of neutropenia. Filgrastim, Nartograstim, and Lenograstim are clinically available in Japan. However, the differences in potential benefit for radiation-induced disorder between these types of rhG-CSFs remain unknown. Therefore, the effects of three different types of rhG-CSFs on granulocyte progenitor cells and expansion of neutrophils from nonirradiated or 2 Gy X-irradiated human CD34+ hematopoietic progenitor cells were examined. For analysis of granulocyte colony-forming units (CFU-G) and a surviving fraction of CFU-G, nonirradiated or X-irradiated CD34+ cells were cultured in methylcellulose containing rhG-CSF. These cells were cultured in serum-free medium supplemented with rhG-CSF, and the expansion and characteristics of neutrophils were analyzed. All three types of rhG-CSFs increased the number of CFU-G in a dose-dependent manner; however, Lenograstim is superior to others because of CFU-G-derived colony formation at relatively low doses. The surviving fraction of CFU-G was independent of the types of rhG-CSFs. Expansion of neutrophils by rhG-CSF was largely attenuated by X-irradiation, though no significant difference in neutrophil number was observed between the three types of rhG-CSFs under both nonirradiation and X-irradiation conditions. In terms of functional characteristics of neutrophils, Lenograstim-induced neutrophils produced high levels of reactive oxygen species compared to Filgrastim, when rhG-CSF was applied to nonirradiated CD34(+) cells. In conclusion, different types of rhG-CSFs lead to different effects when rhG-CSF is applied to nonirradiated CD34+ cells, though Filgrastim, Nartograstim, and Lenograstim show equal effects on X-irradiated CD34+ cells.

Ion-induced tracks in amorphous Si3N4 films

Silicon nitride layers of 140nm thickness were deposited on silicon wafers by low pressure chemical vapour deposition (LPCVD). The samples were irradiated in the electronic slowing-down regime, with either Pb ions of 110MeV (Se=19.3keVnm−1) or Xe ions of 710MeV (Se=22.1keVnm−1). Using infrared absorption spectroscopy, the radiation-induced disorder in Si3N4 was analysed as a function of the ion fluence (up to 4×1013cm−2). Some targets irradiated at low fluences (∼109cm−2) were etched at room temperature in aqueous HF solution (10vol.%) for various durations. The processed surfaces were probed using atomic force microscopy (AFM) in order to evidence etched tracks and to measure their mean surface diameter. The non-simultaneous emergences of the nanopores at the Si3N4/Si interface and the limited etching efficiency allow to conclude that the tracks are probably discontinuous in the present irradiation conditions.