High-dose Irradiation Research Articles

Effect of 60Co γ-rays on dried figs adsorption isotherms and thermodynamic properties.

Irradiation is one of the promising food preservation techniques, but few are known about its impact on foods' water vapor change. In this research, the impact of gamma irradiation on moisture adsorption isotherms of dried figs, one of the most emblematic foods of the Mediterranean diet, at increasing doses (0, 1, 1.5, and 2 kGy) was investigated. The isotherms data of equilibrium points displayed a sigmoid-shaped curve of the type II pattern for both controlled and irradiated dried figs, with a notable effect of irradiation on equilibrium moisture content, which revealed a decreasing pattern as irradiation dose and temperature increase. This effect was also seen in data fitting, where GAB model showed the best prediction statistics for control samples, while Peleg model displayed the most suitable samples irradiated at 1 and 1.5 kGy, then the Enderby model for those treated with 2 kGy. Results of Net isosteric heat of adsorption suggested that high irradiation dose increases the spontaneity of moisture adsorption. Hence, gamma irradiation exhibited a significant effect on the water-specific surface area of which the magnitude was proportional to the increasingly applied doses. This effect was also visibly significant on the optimum water activity [aw (op)] for proper dried fig storage. Indeed, aw was about 0.4243 for control samples, which is much higher compared to irradiated ones (aw = 0.2). Information from this research suggests that gamma irradiation at a dose up to 2 kGy extended the dried figs' shelf life. Since many aspects related to the impact of gamma irradiation on the moisture adsorption isotherms and thermodynamic properties of dried figs as well as in other foods have yet to be further investigated, this study provides interesting results that may be a useful reference for future research direction.

Relationship of irradiated bone marrow volume and neutropenia in patients undergoing concurrent chemoradiation therapy for cervical cancer.

Concurrent chemoradiation therapy (CCRT) is the standard of care in the management of cervical cancer (International Federation of Gynecology and Obstetrics [FIGO] 2008 Stages IB2-IVA). Apart from the myelotoxic effects of chemotherapy, irradiation of pelvic bone marrow (BM) in the radiation field, can also contribute to hematological toxicity. We examined the relationship of irradiated BM volume and neutropenia in cervical cancer patients undergoing CCRT. This prospective study was conducted in a tertiary cancer center with a longitudinal study design. A total of 43 patients undergoing CCRT for cervical cancer were included. Using auto bone segmentation, the external contour of pelvic bones from L4 vertebral body to ischial tuberosities were delineated as BM. The volume of BM receiving 10, 20, 40, 50 Gy was calculated. Complete blood counts were done weekly to evaluate the neutropenia and were graded according to Common Terminology Criteria for Adverse Events, version 3.0. The risk of developing neutropenia was analyzed using logistic regression. Twenty-seven patients (62.8%) received 5 cycles of chemotherapy, 14 patients (32.6%) received 4 cycles of chemotherapy and 2 patients (4.7%) received 3 cycles of chemotherapy. Overall, 22 patients (51.2%) experienced acute neutropenia. On multivariate analysis increased BM V50Gy had a statistically significantly odds of developing any grade of neutropenia (odds ratio [OR] =1.43; 95% confidence interval [CI], 1.03-1.97; P = 0.028). When comparing patients receiving BM V40Gy ≥40% with BM V40Gy <40% odds of any grade of neutropenia was increased (OR = 2.03; 95% CI, 0.55-7.42; P = 0.28). Moreover, when comparing patients receiving BM V50Gy ≥15% with BM V50Gy <15% odds of any grade of neutropenia was increased (OR = 2.13; 95% CI, 0.57-7.97; P = 0.26). High-dose irradiation to the larger volume of BM prevents compensatory hyperplasia which leads to neutropenia in patients undergoing CCRT for cervical cancer.

Gamma irradiation-induced changes in the structural, optical, electrical and radiation shielding properties of lithium borate glasses

Lithium borate glass with the chemical composition 25Li2O–75B2O3 (LBO) was prepared using the melt quenching technique. The changes in their structural, optical and electrical parameters due to gamma irradiation were investigated and its radiation shielding ability was discussed. The as-prepared glasses were transparent, colourless and inclusion free. The glasses were irradiated for 20, 40, 60, 80 and 100 kGy using a60Co gamma source having a dose rate of 2.906 kGy/h. As the radiation dose increases colour centres were formed in the LBO glass, for higher dosages the glasses turned black. The theoretical structural parameters such as density, optical basicity, ionicity, boron-boron separation, bond density, molar volume and oxygen packing density were calculated. The structural changes were carried out using x-ray diffraction confirming the amorphous nature even after a high dose of gamma irradiation. Gamma irradiation induces the formation of BO4. The bandgap decreases from 3.72 to 3.64 eV with an increase in the dose of gamma irradiation. The dielectric spectroscopy and A.C. conductivity mechanism of the glasses were analyzed. The activation energy of the glasses was calculated before and after gamma irradiation using the Arrhenius plot. High doses of gamma irradiation resulted in an increase in activation energy of LBO glasses which increases from 0.12 eV to 0.42 eV at 100 kHz frequency. The radiation shielding ability of the prepared glass samples was estimated using theoretical simulations by Phy-X/PSD software.

Comprehensive effects of heavy-ion beam irradiation on sweet potato (Ipomoea batatas [L.] Lam.).

Sweet potato is a major root crop with nutritious tuberous roots. The mechanism of tuberous root development has not yet been adequately elucidated. Genetic resources are required to develop the molecular understanding of sweet potato. Heavy-ion beams were applied to hexaploid sweet potato for an increase in genetic variation, after which the comprehensive effects of heavy-ion beam irradiation were investigated. In vitro cultured shoots with an axillary bud of 'Beniharuka' were irradiated with Ar-ions at a dose of 1-5 Gy and C-ions at a dose of 5-20 Gy, and three irradiated lines were separated from each irradiated shoot. The shoot regeneration was inhibited at high doses of each ion irradiation. Ar-ion irradiation had an especially high biological effect on shoot regeneration. A total of 335 lines were obtained, consisting of 104 and 231 lines derived from Ar- and C-ion irradiation, respectively. The change in the DNA content of the lines was analyzed by flow cytometry to evaluate the irradiation-induced damage to the DNA. The two lines demonstrated significant differences in the DNA content and changes at the chromosome level. The screening for the morphological mutants was conducted in the field. Some irradiated lines showed inhibited or no tuberous root phenotype as mutant candidates. Additionally, the high-yield mutant candidates were dominated by Ar-ion irradiation. It was indicated that heavy-ion beam mutagenesis is effective in broadening the range of the phenotypes corresponding to tuberous root formation in hexaploid sweet potato.

Gamma radiation effects on plastic optical fibers

• The effect of gamma-ray irradiation on the Plastic Optical Fibers (POFs). • Irradiated POFs had optical losses significantly higher at 535 nm than at 650 nm. • The POFs could be used to connect up to 20 m if gamma-ray does not exceed 17.6 kGy. • The POFs could be used to connect up to 10 m if gamma-ray does not exceed 28.6 kGy. • The absorption edge shifts towards the higher wavelengths due to gamma radiation. We report on our study of the effect of gamma-ray irradiation on Plastic Optical Fibers with a 1 mm diameter for short reach communication. For the study, we used gamma-radiation facilities with 60 Co sources for slow long-term irradiation with a low dose speed of around 70 Gy/hrs and a maximum dose up to 62.90 kGy and a higher speed irradiation dose of around 1 kGy/hrs with a maximum dose up to 51.30 kGy. The optical losses measurement showed that the losses increased linearly during the irradiation and began to decrease immediately after the end of being irradiated. Higher doses of irradiation cause a higher value of the optical loss, and at the dose of 62.9 kGy, the loss was unmeasurably high. A low dose of gamma radiation (1.24 kGy) increased optical losses only slightly and the gamma-ray irradiation at 17.6 kGy for the 20 m long fiber had optical losses of −15.5 dB at 650 nm. The results of the relaxation measurements also showed that optical losses measured at wavelength 535 nm are significantly higher than those at 650 nm. Spectral characteristics measurement done during the irradiation showed that the intensity of the transmitted light decreased and the absorption edge shifted towards the higher wavelengths. Spectral characteristics measured after irradiation during the relaxation period showed that the intensity increased and also that the absorption edge was shifted towards the lower wavelengths, but the same values as before the irradiation were not achieved.

Effects of Chemical Sterilization and Gamma Irradiation on the Biochemical and Biomechanical Properties of Human Tendon Allografts In Vitro Study.

ObjectivePre‐implantation sterilization procedures for tendons are important measures to reduce the risk of disease transmission, however these procedures may compromise tendon microarchitecture and biomechanical properties to varying degrees. We explore the effects of different sterilization procedures on the micro‐histology, biomechanical strength and biochemical properties of human tendon allografts in vitro study.MethodsThe tendon allografts were harvested from cadaveric donors after the donors were serologically screened by antibody or nucleic acid testing of infectious agents. All samples were divided into five groups, which were fresh‐frozen group (control group), 15 kGy gamma irradiation group, 25 kGy gamma irradiation group, 70% ethanol group, and peracetic acid‐ethanol group. Each group included 10 tendons for testing. Histological staining and transmission electron microscopy were applied to observe the internal structure and arrangement of tendon collagen fibers, while the machine learning classifier was trained to distinguish the darker cross‐sections of collagen fibers and brighter backgrounds of the electron micrograph to detect the distribution of diameters of tendon collagen fibers. The viscoelasticity, mechanical properties and material properties of tendon allografts were examined to detect the influence of different intervention factors on the biomechanical properties of tendons.ResultsHistological staining and transmission electron microscopy showed that the structure of fresh‐frozen tendons was similar to the structures of other experimental groups, and no obvious fiber disorder or delamination was observed. In the uniaxial cyclic test, the cyclic creep of 25 kGy irradiation group (1.5%) and peracetic acid‐ethanol group (1.5%) were significantly lower than that of the control group (3.6%, F = 1.52, P = 0.039) while in the load‐to‐failure test, the maximum elongation and maximum strain of the peracetic acid‐ethanol group were significantly higher than those of the control group (F = 4.60, P = 0.010), and there was no significant difference in other biomechanical indicators. According to the experimental results of denatured collagen, it could be seen that no matter which disinfection procedure was used, the denaturation of the tendon sample would be promoted (F = 1.97, P = 0.186), and high‐dose irradiation seemed to cause more damage to collagen fibers than the other two disinfection procedures (296.2 vs 171.1 vs 212.9 μg/g).ConclusionBiomechanical experiments and collagen denaturation tests showed that 15 kGy gamma irradiation and 70% ethanol can preserve the biomechanical strength and biochemical properties of tendons to the greatest extent, and these two sterilization methods are worthy of further promotion.

Impact of gamma irradiation on structural, thermal, and rheological properties of talipot palm (Corypha umbraculifera L.) starch: a stem starch

Talipot palm (Corypha umbraculifera L.) is a non-conventional source of stem starch. The starch obtained from the trunk of the talipot palm was subjected to various doses of irradiation (20 kGy, 50 kGy, 80 kGy, and 100 kGy). The effect of this high dose irradiation on functional, pasting, thermal and rheological properties was studied. The irradiation considerably decreased the amylose content, pH, swelling index, and relative crystallinity, and it increased the carboxyl content and solubility. The L* value, water absorption capacity, and oil absorption capacity were also increased by irradiation. The pasting parameters like pasting temperature, peak viscosity, and final viscosity were considerably decreased by irradiation. The paste clarity and light transmittance of irradiated starches were high at any point of storage. The gel hardness was decreased by γ-irradiation up to a radiation dose of 50 kGy. The FTIR analysis did not show any evidence for the formation of new functional groups. The gelatinization properties, storage modulus, and loss modulus were decreased by irradiation. The principal component analysis showed a good relationship among the different parameters studied.

The oxidative stress, mitochondrial pathway apoptosis, and the antagonistic effects of chrysophanol in SH-SY5Y cells via DTPP-induced photodynamic therapy

BackgroundTo investigate the susceptibility of SH-SY5Y cells to DTPP-based photodynamic therapy (PDT) and the antagonistic effects of chrysophanol (Chr) on PDT. MethodsPDT photocytotoxicity to cells was quantified and determined by exposing increasing concentrations of DTPP between 2.5 to 20 μg/mL to radiation with energy densities of 1.2–9.6 J/cm2 at 630-nm wavelength. Sodium azide (SA, NaN3) and d-mannitol (DM) were employed to study the reaction type of PDT. The photodynamic stress after PDT was assessed by superoxide dismutase (SOD), malondialdehyde (MDA), and total antioxidative capacity (T-AOC) assays. The apoptosis pathway of SH-SY5Y cells after PDT was studied by the determination of JC-1 and caspase-9/Caspase-3 concentrations. MTT and double fluorescence staining assays were applied to study the effect of Chr on cell survival and apoptosis rate in PDT, respectively. PI was used to detect the effect of Chr on cell membrane integrity after DTPP-PDT treatment. ResultsThe dose-dependent killing effect of high DTPP concentrations and irradiation doses were identified. Cell apoptosis is mediated by a mitochondrial pathway with a total apoptosis rate of 33.8% at 10 μg/mL of DTPP after irradiation with 2.4 J/cm2. Oxidative stress was produced by ROS in PDT and non-reversible cell oxidative damage appeared due to the cells’ modulation of the oxidative stress balance during the PDT response. Chr had a- effect on ROS capture and an inhibitory effect on the PDT-induced destruction of cell membranes. ConclusionsSH-SY5Y cells were susceptible to DTPP-PDT, resulting in a mitochondrial apoptosis pathway. There is an antagonistic effect of Chr on PDT in SH-SY5Y neuroblastoma cells.

GATA3 Exerts Distinct Transcriptional Functions to Regulate Radiation Resistance in A549 and H1299 Cells

Background Radiation resistance of lung cancer cells is a vital factor affecting the curative effect of lung cancer. Transcription factor GATA3 is involved in cell proliferation, invasion, and migration and is significantly expressed in a variety of malignancies. However, the molecular mechanism governing GATA3 regulation in lung cancer cells' radiation resistance is unknown. Methods Radiation-resistant cell models (A549-RR and H1299-RR) were made using fractionated high-dose irradiation. Use clone formation, CCK-8, F-actin staining, cell cycle detection, and other experiments to verify whether the model is successfully constructed. Cells were transiently transfected with knockdown or overexpression plasmid. To explore the relationship between GATA3/H3K4me3 and target genes, we used ChIP-qPCR, ChIP-seq, and dual luciferase reporter gene experiments. Xenograft tumor models were used to evaluate the effect of GATA3 depletion on the tumorigenic behavior of lung cancer cells. Results We report that transcription factors GATA3 and H3K4me3 coactivate NRP1 gene transcription when A549 cells develop radiation resistance. However, the mechanism of radiation resistance in H1299 cells is that GATA3 acts as a transcription inhibitor. The decrease of GATA3 will promote the increase of NRP1 transcription, in which H3K4me3 does not play a leading role. Conclusions GATA3, an upstream transcriptional regulator of NRP1 gene, regulates the radioresistance of A549 and H1299 cells by opposite mechanisms, which provides a new target for radiotherapy of lung cancer.

γ-ray Radiation Hardness of CsPbBr3 Single Crystals and Single-Carrier Devices.

The superior environmental stability of all-inorganic metal halide perovskites compared to their organic-inorganic counterparts makes them more promising in practical applications. Here, the stability of an archetypical all-inorganic CsPbBr3 single crystal and its single-carrier devices under 60Co γ-ray irradiation was investigated. The CsPbBr3 single crystal itself shows ostensible hardness as its structural and optical properties present imperceptible changes even with a total ionizing dose of 800 krad. Unexpectedly, the single crystal-based single-carrier devices exhibit apparent dose-dependent hardness. The performance of the hole-only device suffers from more deterioration than the electron-only device under high irradiation doses (>400 krad). Our results reveal that such a discrepancy originates from the different influences of γ-ray irradiation-induced defects on the transport behaviors of holes and electrons in CsPbBr3 single-crystal devices. These findings offer a new understanding of the interaction mechanism between γ-photons and all-inorganic metal halide perovskite-based devices.

Responses of hematopoietic cells after ionizing-irradiation in anemic adult medaka (Oryzias latipes)

Purpose Hematopoietic tissues of vertebrates are highly radiation sensitive and the effects of ionizing radiation on the hematopoiesis have been studied in mammals and teleosts for decades. In this study, radiation responses in the kidney, the main hematopoietic organ in teleosts, were investigated in Japanese medaka (Oryzias latipes), which has been a model animal and a large body of knowledge has been accumulated in radiation biology. Methods Kidney, the main hematopoietic tissue of adult medaka fish, was locally irradiated using proton and carbon ion beams irradiation system of Takasaki Ion Accelerator for Advanced Radiation Application (TIARA), QST, and the effects on peripheral blood cells and histology of the kidney were investigated. Results When only kidneys were locally irradiated with proton or carbon ion beam (15 Gy), the hematopoietic cells in the irradiated kidney and cell density in the peripheral blood decreased 7 days after the irradiation in the same manner as after the whole-body irradiation with γ-rays (15 Gy). These results demonstrate that direct irradiation of the hematopoietic cells in the kidney induced cell death and/or cell cycle arrest and stopped the supply of erythroid cells. Then, the cell density in the peripheral blood recovered to the control level within 4 days and 7 days after the γ-ray and proton beam irradiation (15 Gy), respectively, while the cell density in the peripheral blood did not recover after the carbon ion beam irradiation (15 Gy). The hematopoietic cells in the irradiated kidneys temporarily decreased and recovered to the control level within 21 days after the γ-ray or proton beam irradiation (15 Gy), while it did not recover after the carbon ion beam irradiation (15 Gy). In contrast, the recovery of the cell density in the peripheral blood delayed when anemic medaka were irradiated 1 day after the administration of phenylhydrazine. With and without γ-ray irradiation, a large number of hematopoietic cells was still proliferating in the kidney 7 days after the anemia induction. Conclusions The results obtained strongly suggest that the hematopoietic stem cells in medaka kidney prioritize to proliferate and increase peripheral blood cells to eliminate anemia, even when they are damaged by high-dose irradiation.

ПЕРЕДАЧА РАДИАЦИОННО-ИНДУЦИРОВАННОЙ ГЕНОМНОЙ НЕСТАБИЛЬНОСТИ ОТ ОБЛУЧЕННЫХ РОДИТЕЛЕЙ ПОТОМКАМ

Numerous studies allow to suppose a transmission of radiation-induced genome instability from irradiated parents to their offspring on cell, chromosome and molecular genetic level. This review focuses on transmission of radiation-induced genome instability from irradiated parents to their offspring. Data of genome instability in animal experiments and in offspring of occupationally exposed human or human exposed in a radiation accident, and in offspring of parents exposed to radiotherapy are reviewed. The possible mechanisms of lineage transmission of genome instability are discussed. High dose irradiation can lead to DNA damage, changes in methylation patterns and miRNAs expression in parents and their offspring and result in mutations, chromosome aberration and destabilization of genome. Non-coding RNAs (miRNA, piRNA, nsRNA) are supposed to contribute to transgenerational effects, since they can target genes, change chromatin structure and disregulate gene expression.

Molecular characterization of gastric adenocarcinoma diagnosed in patients previously treated for Hodgkin lymphoma or testicular cancer.

IntroductionThe risk of developing gastric cancer is increased in patients treated with radiotherapy for Hodgkin lymphoma (HL) or testicular cancer (TC). This study aims to assess if gastric adenocarcinoma after treatment for HL/TC (t-GC) is molecularly different from gastric adenocarcinoma in the general population.MethodsPatients were diagnosed with t-GC ≥5 years after treatment for HL/TC. Four molecular subtypes were identified using immunohistochemical and molecular analyses: Epstein-Barr virus (EBV), mismatch repair (MMR) deficiency or microsatellite instability (MSI), aberrant p53 staining as surrogate for chromosomal instability (sCIN), and a surrogate for genomic stability (sGS) without these aberrations. Results were compared with gastric cancer in the general population (p-GC) described in literature.ResultsMolecular subtyping of 90 t-GCs resulted in 3% EBV, 8% MSI, 36% sCIN and 53% sGS. 3/6 of MSI t-GCs had MLH1 promoter methylation and 2/6 were explained by double somatic mutations in MMR genes. T-GCs were more frequently sGS than p-GCs (53% vs. 38%, p = 0.04). T-GC was more frequently sGS in HL/TC patients diagnosed before 1990, than after 1990 (63% vs. 38%, p = 0.03). T-GCs located in the antrum, an area that receives high irradiation doses, were more frequently sGS (61% vs. 28% in p-GCs, p = 0.02).ConclusionOur results demonstrate that t-GCs are more frequently of the sGS subtype than p-GCs. An association of t-GC of the sGS subtype with prior anticancer treatment is suggested by the high frequency in HL/TC patients who were treated before 1990, a time period in which HL/TC treatments were more extensive.

Effect of high-dose delivery on the attachment of meningiomas in Gamma Knife surgery: a retrospective study.

Meningiomas have vascular supply from the tumor attachment on the dura mater. Gamma Knife radiosurgery (GKS) is known to have a vascular obliterating effect. This study aims to determine the benefits of high-dose irradiation to the tumor attachment compared to conventional dose planning in the long-term control of tumor growth with GKS. Two different dose plannings were retrospectively compared in 75 patients with meningioma treated with GKS as a primary treatment. Forty-three patients were irradiated over 20Gy to the tumor attachment. The remaining 32 patients were treated with conventional-dose planning. Tumor growth control, reduction of enhancement on the gadolinium-enhanced magnetic resonance imaging (MRI), and neurological status were retrospectively assessed. The maximum dose on the tumor attachment was significantly higher in the high-dose group (23Gy) than in the conventional group (16Gy). The tumor margin was irradiated with the median of the 50% isodose line in both groups. The prescription doses resulted in 14Gy and 12Gy, respectively. The tumor control rate achieved 91% in both groups during the median follow-up period of 54months. A decrease of enhancement on follow-up MRI was noted in one patient in each group. Kaplan-Meier analysis revealed no statistical difference in the progression-free survival between the two groups. The number of patients with improved neurological status showed no statistical difference. No obvious benefit of high-dose irradiation to the tumor attachment and margin was found in tumor control and neurological status in the long term.

Microstructural evolution of cross-linked polytetrafluoroethylene under gamma irradiation using ultra-small angle X-ray scattering

Cross-linked polytetrafluoroethylene (XPTFE) with excellent wear and radiation resistant is expected to be applied in strong radiation fields. In this study, synchrotron ultra-small angle X-ray scattering (USAXS) techniques combined with in-situ uniaxial stretching were firstly used to study the mechanical property degradation mechanism of XPTFE in terms of micro-structural evolution in real time. As the increase of cross-linking degree, the size and spacing of the scatterers for XPTFE were more unequal. When XPTFE was uniaxially stretched at room temperature, its molecular chains were tilted, and lamellae crystals were elongated and thinned along the stretching direction. When XPTFE was irradiated by γ-rays under air, with increasing absorbed doses, the long period decreased first and then increased, while the gyration radius was reversed. After high-dose irradiation, the mechanical properties of XPTFE were lost, making their stretching processes were dominated by the orientation of some small broken crystals along the stretching direction and accompanied by the formation of voids. But for XPTFE under constant stress uniaxial stretching at variable temperature, its chain segments and molecular chains cannot be oriented even at elevated temperatures, maintaining a degree of thermal stability.

Standardization of the FAO/IAEA Flight Test for Quality Control of Sterile Mosquitoes.

Successful implementation of the sterile insect technique (SIT) against Aedes aegypti and Aedes albopictus relies on maintaining a consistent release of high-quality sterile males. Affordable, rapid, practical quality control tools based on the male’s flight ability (ability to escape from a flight device) may contribute to meeting this requirement. Therefore, this study aims to standardize the use of the original FAO/IAEA rapid quality control flight test device (FTD) (version 1.0), while improving handling conditions and reducing the device’s overall cost by assessing factors that could impact the subsequent flight ability of Aedes mosquitoes. The new FTD (version 1.1) is easier to use. The most important factors affecting escape rates were found to be tube color (or “shade”), the combined use of a lure and fan, mosquito species, and mosquito age and density (25; 50; 75; 100 males). Other factors measured but found to be less important were the duration of the test (30, 60, 90, 120 min), fan speed (normal 3000 rpm vs. high 6000 rpm), and mosquito strain origin. In addition, a cheaper version of the FTD (version 2.0) that holds eight individual tubes instead of 40 was designed and successfully validated against the new FTD (version 1.1). It was sensitive enough to distinguish between the effects of cold stress and high irradiation dose. Therefore, the eight-tube FTD may be used to assess Aedes’ flight ability. This study demonstrated that the new designs (versions 1.1 and 2.0) of the FTD could be used for standard routine quality assessments of Aedes mosquitoes required for an SIT and other male release-based programs.

Study of Morphological, Structural, and Strength Properties of Model Prototypes of New Generation TRISO Fuels.

The purpose of this work is to characterize the morphological, structural, and strength properties of model prototypes of new-generation TRi-structural ISOtropic particle fuel (TRISO) designed for Generation IV high-temperature gas reactors (HTGR-type). The choice of model structures consisting of inner pyrolytic carbon (I-PyC), silicon carbide (SiC), and outer pyrolytic carbon (O-PyC) as objects of research is motivated by their potential use in creating a new generation of fuel for high-temperature nuclear reactors. To fully assess their full functional value, it is necessary to understand the mechanisms of resistance to external influences, including mechanical, as in the process of operation there may be external factors associated with deformation and leading to the destruction of the surface of fuel structures, which will critically affect the service life. The objective of these studies is to obtain new data on the fuel properties, as well as their resistance to external influences arising from mechanical friction. Such studies are necessary for further tests of this fuel on corrosion and irradiation resistance, as closely as possible to real conditions in the reactor. The research revealed that the study samples have a high degree of resistance to external mechanical influences, due to the high strength of the upper layer consisting of pyrolytic carbon. The presented results of the radiation resistance of TRISO fuel testify to the high resistance of the near-surface layer to high-dose irradiation.

A multi-component nanocrystalline FeCrV alloy with improved mechanical properties and excellent irradiation resistance

An equiatomic low-activated FeCrV ternary alloy was prepared by mechanical alloying and spark plasma sintering. The BCC solid solution alloy exhibited an excellent strength-ductility synergy properties, which was 1.85 ​GPa compressive yield strength, 3.04 ​GPa fracture strength and more than 28% plasticity at room temperature. Even at an elevated temperature of 600 ​°C, its yield strength was still more than 1 ​GPa, revealing a pronounced high temperature resistance. The FeCrV alloy had a homogeneous microstructure with high-density dislocations. A nanocrystalline characteristic was demonstrated and the average grain size was about 322 ​nm, leading to the improved mechanical properties. The strengthening mechanism was discussed in detail and the contributions of strengthening factors were calculated. The FeCrV alloy was irradiated up to 160 dpa with 2 ​MeV Au2+ ions at 573 ​K. The nanoindentation test was carried out to simply evaluate the hardening degree under such a high dose irradiation with heavy ions. The semi-quantitative analysis results show that FeCrV alloy has an excellent irradiation tolerance compared with pure Fe.

Durvalumab after Sequential High Dose Chemoradiotherapy versus Standard of Care (SoC) for Stage III NSCLC: A Bi-Centric Trospective Comparison Focusing on Pulmonary Toxicity.

Simple SummaryThe standard of care (SoC) for patients with unresectable stage III non-small-cell lung cancer is concurrent chemoradiation followed by durvalumab. Because of co-morbidities, however, the concurrent approach is only amenable for about one-third of patients. While sequential regimens are usually regarded as palliative, these schedules applied in a dose-escalated mode may be part of a curative approach. As the combination of high-dose radiation and durvalumab remains a question of ongoing research, this retrospective study aims at evaluating pulmonary side effects after sequential chemoradiotherapy with high-dose irradiation compared to SoC. Radiation dose escalation showed no excess pulmonary toxicity such as pneumonitis but tendentially better intrathoracic control, suggesting that this alternative approach is safe and feasible.Introduction: The standard of care (SoC) for unresectable stage III non-small-cell lung cancer (NSCLC) is durvalumab maintenance therapy after concurrent chemoradiation in patients with PD-L1 > 1%. However, the concurrent approach is only amenable for about one-third of patients due to co-morbidities. Although sequential regimens are usually not regarded as curative, these schedules applied in a dose-escalated manner may be similarly radical as SoC. As combining high-dose radiation and durvalumab remains a question of debate this retrospective bi-center study aims to evaluate pulmonary toxicity after high-dose chemoradiotherapy beyond 70 Gy compared to SoC. Patients and Methods: Patients with NSCLC stage III received durvalumab after either sequential high-dose chemoradiation or concomitant SoC. Chemotherapy consisted of platinum combined with either pemetrexed, taxotere, vinorelbine, or gemcitabine. The primary endpoint was short-term pulmonary toxicity occurring within six months after the end of radiotherapy (RT). Results: A total of 78 patients were eligible for this analysis. 18F-FDG-PET-CT, cranial MRT, and histological/cytological verification were mandatory in the diagnostic work-up. The high-dose and SoC group included 42/78 (53.8%) and 36/78 (46.2%) patients, respectively, which were matched according to baseline clinical variables. While the interval between the end of RT and the start of durvalumab was equal in both groups (p = 0.841), more courses were administered in the high-dose cohort (p = 0.031). Pulmonary toxicity was similar in both groups (p = 0.599), whereas intrathoracic disease control was better in the high-dose group (local control p = 0.081, regional control p = 0.184). Conclusion: The data of this hypothesis-generating study suggest that sequential high-dose chemoradiation followed by durvalumab might be similar to SoC in terms of pulmonary toxicity and potentially more effective with respect to intra-thoracic disease control. Larger trials with a prospective design are warranted to validate these results.

O-275 Is there a case for ovarian tissue cryopreservation in young girls and Turner syndrome patients?

Abstract The development of new cancer drugs and drug combinations has led to a dramatic increase in the survival rates of prepubertal and postpubertal girls undergoing myeloablative treatment for malignant or non-malignant diseases. This includes girls who will receive high doses of alkylating agents, total body irradiation, or high radiation doses to the craniospinal, abdominal or pelvic area. Chemotherapy is also used as a conditioning regimen before hematopoietic stem cell transplantation for treatment of, for example, beta thalassaemia or homozygous sickle-cell anaemia. The corollary of improved treatment outcomes of childhood diseases is that many survivors are now at risk of multi-faceted, chronic morbidity, impaired quality-of-life and psychosocial problems. Depending on the nature and duration of their treatment some, but not all, young patients facing fertility threatening diagnosis and treatments will have an increased risk of adverse pregnancy outcomes and premature ovarian insufficiency (POI) as their future fertile potential will be defined by the number of follicles remaining in their ovaries following completion of their chemotherapy/radiotherapy. While a fully functioning hypothalamic-pituitary-ovarian axis and uterus are vital to the reproductive potential of adult females, Ovarian tissue cryopreservation (OTC) is now being used to safeguard the future fertility of prepubertal and adolescent girls and young women undergoing treatments that have a high risk of causing POI. OTC is increasingly advocated for young girls receiving an early diagnosis of the most common sex chromosome abnormality- Turner Syndrome (TS) who have a high risk of POI. In theory the ovaries of girls, including TS patients with an adequate ovarian reserve, are well suited to OTC as their ovaries contain high numbers primordial follicles which can be used to preserve future fertility. Ovarian tissue can be removed laparoscopically and early staged follicles cryopreserved in situ within slices of cortex. The operative approaches used for tissue removal from paediatric and adolescent patients are variable and invasive and are dependent on patient age, health and ovarian reserve at the time of tissue recovery. Extensive research has shown that ovarian cryopreservation techniques are robust and that experienced practitioners can achieve high levels of survival of both the ovarian stroma and follicle compartments post thaw. Cryobanked ovarian cortex collected from prepubertal and postpubertal girls has been shown to function normally and support fertility, pregnancy to term and the birth of healthy babies following orthotopic autografting in adulthood. Regardless of patient age at tissue preservation, autografting of frozen-thawed ovarian cortex at either the site of the retained ovary or into the peritoneal cavity results in an immediate and significant follicle loss due to ischaemia and accelerated apoptosis. Those primordial follicles that survive graft revascularization have been shown to have the capacity to grow to preovulatory stages, to reinstate hormonal function and to undergo ovulation and restore natural fertility. Alternatively, follicle growth can be induced in autografted tissue by controlled ovarian stimulation before oocyte harvest for insemination in vitro using assisted reproductive technologies. Graft functional longevity remains variable between patients and may extend from months to years. Alternative methods for fertility restoration such as the complete in vitro growth and maturation of oocytes and the construction of artificial ovaries remain unproven in humans. While OTC can be recommended for young girls at high risk of developing ovarian insufficiency for genetic reasons or following high dose chemotherapy and/or irradiation, to date very few young patients with stored ovarian tissue have used their tissue for fertility restoration. OTC therefore remains experimental and further research is needed to establish the risks, benefits, efficacy, safety and ethical and clinical frameworks for offering fertility preservation to girls during childhood and adolescence and to girls with TS.