High-dose Irradiation Research Articles

Microstructure evolution in Cr0.6FeNiMn and CrFeNiCoPd under ion irradiation

It has been suggested that CrFeNi-based multi-principal element alloys (MPEAs) may be attractive materials for nuclear energy applications due to promising mechanical properties and possible increased resistance to irradiation damage compared to traditional alloys. However, phase stability during irradiation at intermediate temperatures remains a concern and expanding the range of irradiation conditions is of prime importance to understand the radiation damage mechanisms operating in these alloys. Here, the effects of dose and dose rate on the microstructures of two model alloys, Cr0.6FeNiMn and CrFeNiCoPd, during heavy ion irradiation were investigated. Both alloys exhibited phase decomposition under thermal aging and ion irradiation. Under ion irradiation, the decomposition process followed a thermodynamically driven radiation-enhanced diffusion process that is susceptible to cascade mixing effects at high ion irradiation dose rates.

All-in-one benzophenone structure realizes the simultaneous improvement of flexibility and radiation resistance of polyurethane

In the environment of nuclear industry, space navigation and radiotherapy, a large number of high-energy rays pose a severe challenge to the radiation resistance of polyurethane (PU) elastomer. However, the traditional radiation resistance strategy of linking aromatic hydrocarbons into the molecular chain would severely sacrifice polymer flexibility, not suitable for flexible polymers. In this study, an all-in-one strategy to develop the radiotolerant and flexible PU elastomer is proposed through integrating radiation-resistance function with phase structure regulation. Concretely, the benzophenone (BP) structure is linked into the hard segment of PU to prepare the BP modified PU (BP-PU). In terms of flexibility, benefiting from the hydrogen-bond interaction between carbonyl group of BP and amide group of PU, the BP structure could inhibit the growth of hard phase to achieve the increase of PU flexibility instead of reduction. In terms of radiotolerance, the BP structure in BP-PU elastomer was found to perform dual radiation-resistance function that efficiently dissipates radiation-energy to reduce radical generation and trap the active radical. Under gamma-ray irradiation, BP-PU elastomer exhibited excellent chemical stability and radiotolerance in macro-properties. Notably, after high-dose irradiation, BP-PU elastomer not only shown a slight change in macroscopic color, but also performed twice the mechanical durability of control group. This work achieved the synchronous improvement of radiotolerance and flexibility of PU for the first time, providing an easy and promising avenue for the development of radiotolerant and flexible PU to fill the lack in radiation-related fields.

Effects of Structural Radiation Disorder in the Near-Surface Layer of Alloys Based on NbTiVZr Compounds Depending on the Variation of Alloy Components

This research investigated how changes in the composition of Nb–Ti–V–Zr-based alloys affect their resistance to radiation damage and the preservation of strength characteristics when exposed to the heavy ions Kr15+ and Xe23+. These heavy ions simulate the impact of nuclear fuel fission fragments on the material. The primary objective of this study was to explore how variations in alloy components influence radiation resistance and the retention of alloy strength properties. Accumulation of radiation defects can potentially lead to embrittlement and a decrease in resistance to external factors during operation. An analysis of the X-ray diffraction data obtained from the initial alloy samples, in relation to the variations in the number of components, revealed that an increase in the number of components leads to the formation of a denser crystal structure. Additionally, this resulted in the emergence of a dislocation strengthening factor associated with changes in crystallite size. Concurrently, when assessing changes in the strength characteristics of the irradiated alloys, it was observed that the NbTiV and NbTiVZr alloys demonstrated the highest resistance to strength property degradation, specifically a 2.5- to 5-fold increase in resistance against a significant decrease in hardness. It was confirmed that the significant factor contributing towards the enhancement and preservation of the structural and strength properties is the dislocation strengthening mechanism. An increase in dislocation strengthening effectively enhances resistance against destructive embrittlement, particularly when exposed to high-dose irradiation.

Study of Gas Swelling Processes under Irradiation with Protons and He2+ Ions in Li4SiO4–Li2TiO3 Ceramics

One of the important areas of research in the energy sector is the study of the prospects for using new types of nuclear fuel, including tritium, which is one of the most promising types of fuel for thermonuclear energy. At the same time, for the production of tritium in the required quantities, the one that is the most optimal is the use of blanket materials based on lithium-containing ceramics. This is where tritium is released from lithium under the influence of neutron irradiation. The paper presents the results of an investigation of the influence of two-phase ceramics based on Li4SiO4–Li2TiO3 compounds on the resistance to external influences (mechanical loads) during the accumulation of hydrogen and helium (He2+) in the near-surface layer. The interest in such studies is primarily related to the search for solutions in the field of creating high-strength materials for tritium generation for its further use as nuclear fuel for thermonuclear fusion, as well as to the study of the mechanisms of the influence of different phases on the changes in the strength properties of ceramics, which provides an opportunity to expand fundamental knowledge in this area. The proposed method of obtaining two-phase ceramics by mechanical-chemical mixing and subsequent sintering into spherical particles enables the production of well-structured, high-strength ceramics of specified geometric dimensions (limited only by the dimensions of the mold) with a controlled phase ratio. During the experiments, it was found that increasing the content of Li4SiO4 phase in ceramics leads to an increase in strength characteristics (hardness, resistance to cracking) by 15–20% compared to single-phase ceramics. The most optimal composition of two-phase ceramics with high resistance to destructive embrittlement is the ratio of phases 0.75Li4SiO4–0.25Li2TiO3. One of the factors explaining the increase in resistance to destructive embrittlement under high-dose irradiation for two-phase ceramics is the increased dislocation density and the presence of interphase or intergranular boundaries, the high concentration of which leads to the creation of additional obstacles to the agglomeration of hydrogen and helium in the near-surface layer.

Lattice-Gradient Perovskite KTaO3 Films for an Ultrastable and Low-Dose X-Ray Detector.

Conventional indirect X-ray detectors employ scintillating phosphors to convert X-ray photons into photodiode-detectable visible photons, leading to low conversion efficiencies, low spatial resolutions, and optical crosstalk. Consequently, X-ray detectors that directly convert photons into electric signals have long been desired for high-performance medical imaging and industrial inspection. Although emerging hybrid inorganic-organic halide perovskites, such as CH3 NH3 PbI3 and CH3 NH3 PbBr3 , exhibit high sensitivity, they have salient drawbacks including structural instability, ion motion, and the use of toxic Pb. Here, this work reports an ultrastable, low-dose X-ray detector comprising KTaO3 perovskite films epitaxially grown on a Nb-doped strontium titanate substrate using a low-cost solution method. The detector exhibits a stable photocurrent under high-dose irradiation, high-temperature (200 °C), and aqueous conditions. Moreover, the prototype KTaO3 -film-based detector exhibits a 150-fold higher sensitivity (3150 µC Gyair -1 cm-2 ) and 150-fold lower detection limit (<40 nGyair s-1 ) than those of commercial α-Se-based direct detectors. Systematic investigations reveal that the high stability of the detector originates from the strong covalent bonds within the KTaO3 film, whereas the low detection limit is due to a lattice-gradient-driven built-in electric field and the high insulating property of KTaO3 film. This study unveils a new path toward the fabrication of green, stable, and low-dose X-ray detectors using oxide perovskite films, which have significant application potential in medical imaging and security operations.

Differential Antioxidant Response to Supplemental UV-B Irradiation and Sunlight in Three Basil Varieties.

Three basil plant varieties (Ocimum basilicum var. Genovese, Ocimum × citriodorum, and Ocimum basilicum var. purpurascens) were grown under moderate light (about 300 µmol photons m-2 s-1) in a glasshouse or growth chamber and then either transferred to an open field (average daily dose: 29.2 kJ m-2 d-1) or additionally exposed to UV-B irradiation in a growth chamber (29.16 kJ m-2 d-1), to reveal the variety-specific and light-specific acclimation responses. Total antioxidant capacity (TAC), phenolic profile, ascorbate content, and class III peroxidase (POD) activity were used to determine the antioxidant status of leaves under all four light regimes. Exposure to high solar irradiation at the open field resulted in an increase in TAC, total hydroxycinnamic acids (HCAs, especially caffeic acid), flavonoids, and epidermal UV-absorbing substances in all three varieties, as well as a two-fold increase in the leaf dry/fresh weight ratio. The supplemental UV-B irradiation induced preferential accumulation of HCAs (rosmarinic acid) over flavonoids, increased TAC and POD activity, but decreased the ascorbate content in the leaves, and inhibited the accumulation of epidermal flavonoids in all basil varieties. Furthermore, characteristic leaf curling and UV-B-induced inhibition of plant growth were observed in all basil varieties, while a pro-oxidant effect of UV-B was indicated with H2O2 accumulation in the leaves and spotty leaf browning. The extent of these morphological changes, and oxidative damage depended on the basil cultivar, implies a genotype-specific tolerance mechanism to high doses of UV-B irradiation.

Bimodal structured chromium-tungsten composite as plasma-facing materials: Sinterability, mechanical properties, and deuterium retention assessment

Even though tungsten (W) is considered to be the most favored plasma-facing material (PFM) for nuclear fusion reactors thanks to its beneficial physical properties, its advantage for those plasma-facing components to be subjected to medium heat flux and high neutron irradiation dose is compromised by unfavorable nuclear behavior such as intermediate-level radioactive waste activation and embrittlement caused by lattice damage and transmutation. Chromium (Cr) or Cr-based materials may have the potential to mitigate these shortcomings while maintaining acceptable thermal and physical performances required for PFM. They could offer attractive design options, particularly for those parts where the particle fluxes are relatively low and the heat flux is not too high (≤ 5 MW/m²) while nuclear loads are high (≥ 5 dpa). In this article, we report the first results of a preliminary technology feasibility study for an engineered Cr-based material fabricated based on a powder-metallurgical route. To explore an optimal metallurgical condition ensuring reasonable mechanical properties and low deuterium retention, a novel two-phase Cr-W composite was developed via current-assisted rapid sintering at low sintering temperature. The composite showed a cell-like bimodal microstructure consisting of a coarse-grained Cr phase surrounded by a 3D interconnected network of an ultrafine-grained W phase. The composite exhibited substantial improvements in ductility as well as high-temperature strength compared to pure W and Cr. After undergoing W heavy ion irradiation, the damaged Cr-W composite with a two-phase bimodal microstructure showed a comparable deuterium retention capacity to pure W. Finally, the potential applicability as PFM is discussed.

Dose and dose rate dependence of precipitation in a series of surveillance RPV steels under ion and neutron irradiation

Life extension of light water reactors requires robust models to predict the embrittlement of reactor pressure vessel (RPV) steels under long-term neutron irradiation. Embrittlement is due to nanoscale precipitation hardening by phases containing Cu, Mn, Ni, and Si, resulting in increases of the ductile to brittle transition temperature. Embrittlement data for low flux, high fluence extended life conditions, up to 80 years or more, are largely not available. Thus, higher flux, accelerated test reactor irradiations have been used to help develop models to predict low flux embrittlement at high fluence. Here flux, or dose rate, is expressed in units of displacements per atom per second (dpa/s). The dose rate can significantly influence precipitate evolution in a way that depends on fluence (dpa), temperature, and alloy composition, as well as flux itself. Here, we explore precipitation in surveillance steels with varying compositions at high fluxes (10−5–10−6 dpa/s) produced using 70 MeV Fe2+ ion irradiations. Atom probe tomography was used to characterize the dose dependence of precipitation at very high ion irradiation dose rates, and to evaluate corresponding similarities or differences compared to neutron irradiated steels at a much lower dose rate of ≈ 5 × 10−9 dpa/s. The data show that, on average, the ion irradiation precipitate volume fractions increase by factors of ∼ 1.5 to 2 between 0.3 dpa and 1.2 dpa. Limited data show that the major effect of neutron versus ion irradiation is the former has lower precipitate number densities and larger sizes. Otherwise, the precipitates are remarkably similar in composition and volume fraction.

Stereotactic body radiation therapy in the treatment of early-stage non-small cell lung cancer.

Stereotactic body radiation therapy (SBRT) is now a standard treatment option for patients with early-stage non-small cell lung cancer (ES-NSCLC) who are unfit for surgery or refuse to undergo an operation. SBRT is a method of external beam radiotherapy that accurately delivers a high dose of irradiation in one or few treatment fractions. Intensive regimens of biologically effective dose ≥ 100 Gy are associated with good local control and overall survival, higher than in conventionally fractionated radiotherapy. There are still controversial areas in the SBRT indication where data are limited - indications for elderly and comorbid patients, indications for treatment without histological verification, treatment of central/ultracentral lesions, indications for tumors larger than 5 cm, indications for operable patients. The optimal follow-up practice of these patients also remains unclear, including the frequency of imaging, the use of PET-CT, and requirements for biopsy. CT changes after SBRT differ from those following conventional radiotherapy and it is difficult to distinguish them from tumor recurrence. Due to the high local control achieved with lung SBRT, data on the treatment of local failure are insufficient. The aim of the publication is to demonstrate the current information and the importance of SBRT for patients with ES-NSCLC.

Comparative study of electron beam and gamma ray irradiation effects in RPC glass detector materials by positron lifetime spectroscopy

This work is intended to compare the electron beam and gamma ray irradiation induced microstructural effects and electrical conductivity in glass Resistive Plate Chamber (RPC) detector materials with different doses. Positron annihilation lifetime spectroscopic (PALS) technique was used to analyze the irradiation induced structural modifications in the RPC detector materials. PALS analysis at lower doses indicates the increased void size with the creation of additional sites in the glass network upon both the irradiation sources. At higher irradiation doses, the reduced void size shows the enhanced chemical bonding between the tetrahedral sites of Si-O-Si and hence increases the short range order in the silica glass. The variation of DC conductivity upon both the irradiation techniques correlates well with the measured void size. Gamma ray irradiation produced more structural changes in the glass samples as compared to the electron beam irradiation.

Ten-Year Outcomes of Hypofractionated (45 Gy in 9 Fractions) Intensity Modulated Radiotherapy for Localized Prostate Cancer.

We reported 10-year outcomes of localized prostate cancers treated with hypofractionated intensity-modulated radiotherapy of 45 Gy in 9 consecutive fractions. From October 2011 to April 2017, thirty patients with localized prostate cancer were enrolled in this prospective trial. The median age of the patients was 72.5 years. According to NCCN recurrence risk criteria, eight patients were at low-risk group, 17 at intermediate risk group, 5 at high-risk group. All patients were treated with hypofractionated intensity-modulated radiotherapy (IMRT) of 45 Gy in 9 consecutive fractions to their prostate with or without seminal vesicles. Before radiotherapy, three gold fiducials were implanted into the prostate. In order to reduce the rectal high dose irradiation volume, an inflated rectal balloon was placed in the rectum at simulation and every treatment and patients were treated with comfortable full bladder. Static Intensity-modulated radiotherapy (SIMRT) was applied in 1 patient, Volumetric Modulated Arc Therapy (VMAT) in 27 patients, and tomotherapy in 2 patients. Image guided radiotherapy (IGRT) with gold fiducial registration was adopted. Twenty-six patients also received androgen deprivation therapy (ADT). The median time of ADT was 6 months. Progression⁃free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier analysis. All grade ≥1 genitourinary (GU) and gastrointestinal (GI) toxicities were recorded using Common Terminology Criteria for Adverse Event version 5.0 (CTCAE 5.0) and Radiation Therapy Oncology Group (RTOG) late morbidity criteria, and GU and GI toxicities were cumulatively calculated. After a median follow-up of 102 months (65∼131 months), the 10-year OS was 90.0% (95% confidence interval, 83.3%-96.7%), and the 10-year PFS was 86.5% (95% confidence interval, 79.1%-93.9%). According to CTCAE 5.0, grade 1 acute gastrointestinal (GI) toxicity developed in 12 patients, grade 2 in 2 patients, grade 3 in 2 patients, and grade 1 acute genitourinary (GU) toxicity developed in 12 patients, grade 2 in 2 patients, and no grade 3 or higher toxicity occurred. According to RTOG late morbidity criteria, late (≥3 months after radiotherapy) grade 1 GI toxicity developed in 4 patients (13.3%), grade 2 in 1 (3.3%), grade 3 in 1 (3.3%), and late grade 1 GU toxicity occurred in 1 patient (3.3%), grade 2 in 1 (3.3%), grade 3 in 1 (3.3%). No grade 4 or higher GI and GU toxicities developed. Only one grade 3 GI and one grade 2 GU toxicities were observed for the maximum toxicity at the last follow-up. The potency was not evaluated. The 10-year oncologic outcomes of this shortened hypofractionated IMRT regimen for mainly low/intermediate risk prostate cancer patients is favorable with acceptable acute and late toxicities.

The Early and Late Effects of High-Dose Irradiation on Cardiac Injury in a Rat Model

Radiation-induced heart disease is a critical concern after radiotherapy (RT) for thoracic and chest wall tumors; however, the biological effects and mechanisms are still unknown. In this study, we investigated dose-responsive functional and pathological changes in rat hearts at 1, 3, and 5 months after high-dose irradiation. Then, we sought to elucidate the underlying mechanisms of myocardial changes induced by high-dose irradiation. Whole hearts of rats (N = 72) were irradiated with a single fraction of 0 (control), 10, 20, or 30 Gy and allocated into three groups according to the follow-up period after RT: baseline, one, three, and five months. During follow-up periods, rats underwent functional evaluation by electrocardiogram and echocardiography at 4-week intervals. If a rat's body weight decreased by 20% or more, it was considered premature death, and the heart was explanted immediately. Otherwise, all hearts were explanted when each group's follow-up period was completed. Pathological changes of cardiac structures were evaluated using a light microscope after staining with hematoxylin-eosin, Masson's trichrome, α-smooth muscle actin, desmin, and connexin-43. All rats irradiated with 0 or 10 Gy completed their follow-up periods with continuously increasing body weight. However, among rats irradiated with 20 or 30 Gy, half of the rats died prematurely at 8-10 weeks after RT, and the remainder survived until 20 weeks. In echocardiography, increased wall thickness and E/E' ratio, and decreased end-diastolic volume were observed in 20-30 Gy groups compared to 0-10 Gy groups from 8 weeks after RT. Ejection fraction was preserved in all groups. In pathological review, 20-30 Gy groups demonstrated diffuse inflammation and vacuolization at 4 weeks. Then, at 8 weeks, prominent fibrotic changes and intercalated disc disruptions were observed. Notably, fibrotic changes were somewhat resolved at 20 weeks, but intercalated disc disruptions were not repaired until 20 weeks. The 0 and 10 Gy groups showed no significant changes in both functional and pathological analyses. Rats irradiated with 20 or 30 Gy showed diastolic dysfunction in functional analysis and time-dependent myocardial changes in pathological analysis. Radiation-induced fibrosis might be a "reactive" fibrosis, which could proceed to either a profibrotic course (progressive fibrosis) or an anti-fibrotic course (recovery phase). Further studies are needed to identify whether high-dose irradiation-induced cardiac fibrosis could be reversible.

Photoluminescence and thermoluminescence properties of pure and rare-earth-doped ZrO2 prepared by Pechini-type sol-gel.

In this article, photoluminescence (PL) and thermoluminescence (TL) properties of ZrO2 , ZrO2 :Dy3+ , ZrO2 :Dy3+ -Gd3+ , ZrO2 :Dy3+ -Yb3+ , ZrO2 :Dy3+ -Er3+ , and ZrO2 :Dy3+ -Sm3+ phosphors synthesized by the Pechini method were investigated. The crystal structure, thermal properties, morphology, PL and TL properties were investigated using X-ray powder diffraction (XRD), differential thermal analysis/thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), PL and TL, respectively. The room temperature emission bands corresponding to 4 F9/2 →6 HJ (J= 9/2, 11/2, 13/2 and 15/2) transitions of Dy3+ ions were measured. The phosphors were analysed using Tm -TSTOP , variable dose, and computerized glow curve fitting methods. Reusability, dose-response, and fading characteristics were investigated. The phosphors have a natural TL emission that vanished by heating treatment. Moreover, new peaks with similar properties to the natural emissions were observed after high-dose irradiation and long-term fading experiments. The glow curves of the phosphors have 13 individual peaks and many low- and high-temperature satellite peaks. The origin of the peaks is ZrO2 host material and doping with rare-earth ions (Gd3+ , Dy3+ , Yb3+ , Er3+ and Sm3+ ) does not lead to a new glow peak. The dopants cause drastic changes in individual peak intensities of ZrO2 .The initial fading rates of all the phosphors are relatively fast, but they slow down as time goes on.

Testing of a new ionizing radiation detector based on multimode optical fibers

"This paper presents our results investigation to evaluation effects of the electron beams radiation generated in multimode optical fibers at high irradiation doses in order to develop an ionizing radiation dosimeter. The radiation induced attenuation has been shown to exhibit a linear dependence as a function on the applied dose on a certain doses range and after the irradiation the optical fibers go through a “recovery process” during which the optical properties improve again. The surface morphological changes due to electron beam irradiation were investigated by Scanning Electron Microscopy and Atomic Force Microscopy."

Dislocation loops, segregation and hardening induced by high-dose ion irradiation of NbMoTaW and VCrTaW high-entropy alloy coatings on the T91 substrate

NbMoTaW and VCrTaW high-entropy alloys (HEA) coatings with near-equal atomic ratios were deposited onto the T91 substrate by magnetron sputtering. The two HEA coatings and the T91 substrate were irradiated to the peak damage 50 displacements per atom (dpa) and 100 dpa using 2.7 MeV Si2+ at 550 °C. X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and nanoindentation techniques were used to study the changes in grain morphology, microstructure, element distribution and hardness before and after irradiation. The results showed that the grain structure was stable and the coatings were closely bonded to the substrate after irradiation. The elements (Ta and W) near the grain boundary in NbMoTaW coating were depleted before irradiation, but they became homogenized after irradiation. A large number of dislocation loops were observed in both the T91 substrate and HEA coatings after irradiation, the HEA coatings significantly increased the doses required for the full evolution of the dislocation loops. With the increase of damage doses, the dislocation loops size of HEA coatings increased and the number density decreased. The size of the dislocation loops of the two coatings was similar, while the number density of the dislocation loops of NbMoTaW coating was lower than that of VCrTaW coating. Both HEA coatings were significantly hardened after irradiation and the hardening rate of NbMoTaW coating was lower than that of VCrTaW coating. Interestingly, the hardening rate of 50 dpa was higher than 100 dpa for both HEA coatings, which was determined by softening factor and hardening factor in the irradiation process. Based on the defects and hardening rate caused by irradiation, it was preliminarily concluded that NbMoTaW coating had better irradiation resistance, and the above results provide an important reference for the subsequent optimization of lead-based fast reactors structural materials.

P04.06.A A PHASE II MONOCENTRIC STUDY OF LIMITED USE OF HIGH DOSE OF CHEMOTHERAPY AND PROTON THERAPY IN PEDIATRIC HIGH RISK MEDULLOBLASTOMA AND OTHER EMBRYONAL CANCERS

Abstract BACKGROUND Despite the multimodal approach, medulloblastoma remains a leading cause of cancer-related death in children. We proposed the preliminary data of an interventional, open-label, phase II study to evaluate the safety and efficacy of standard and high-dose chemotherapy associated with craniospinal proton therapy in patients with metastatic medulloblastoma and other embryonal cancers. MATERIAL AND METHODS A total of 19 patients have been enrolled from the beginning of the study from February 2018 to May 2022 . The median age was 7,5 years (range; 13 males and 6 female). The protocol predicted the first phase of induction with 4 cycles of chemotherapy. After induction patients with favorable histology without evidence of disease were enrolled to proton therapy (with concomitant vinorelbine biweekly). The maintenance phase with Lomustine repeated every 9 weeks and vinorelbine every 3 weeks for overall 12-18 months (PR). Conversely LC/A MB, pineoblastoma or other high risk embryonic tumors were subjected to consolidation phase with high dose of chemotherapy with tiothepa followed by autologous HSC transplant and successive maintenance phase of 6 months. RESULTS At December 2022, the median follow up was 23 months. 18 patients had high risk medulloblastoma and one had a primary leptomeningeal primitive neuroectodermal tumor. After the induction phase 14 patients showed CR, 3 PR, 1PD, 1SD. At subsequent re-evaluations two of the three patients with PR, showed disease control, one CR and the other SD and the patient with PD showed CR. At the end of proton therapy 18 patients had CR. During the reporting period three patient died for progression of the underlying disease. At 15 months from the start of treatment the PFS and OS were 68.8% (95% CI: 34.1% - 87.6%) and 94.7% (95% CI: 68.1% - 99.2%) respectively. The principal expected side effects of chemotherapy were hematology toxicity (fever and neutropenia prevalent after etoposide and carboplatin plus vinorelbine). Among the unexpected side effect was CMV retinopathy with complete blindness and leukoencephalopathy after high dose of thiotepa and proton irradiation. CONCLUSION As the study did not reveal any safety issues, proton therapy combined with intensive chemotherapy, and myeloablative chemotherapy only in selected cases and always before irradiation, proved feasible and successful in treating high-risk medulloblastomas and other embryonal tumors.

Critical Evaluation of the Methods for the Characterization of the Degree of Sulfonation for Electron Beam Irradiated and Non-Irradiated Sulfonated Poly(ether ether ketone) Membranes.

Sulfonated poly(ether ether ketone) (SPEEK) materials are promising candidates for replacing Nafion™ in applications such as proton exchange membrane (PEM) and direct methanol fuel cells. SPEEK membranes have several advantages such as low cost, thermal and radiation stability and controllable physicochemical and mechanical properties, which depend on the degree of sulfonation (DS). Commercial PEEK was homogenously sulfonated up to a DS of 60-90% and the membranes were prepared using a solvent casting method. Part of the samples were irradiated with a 10 MeV electron beam up to a 500 kGy dose to assess the ionizing radiation-induced effects. Both non-irradiated and irradiated membranes were characterized by Fourier Transformation infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), proton nuclear magnetic resonance (1H-NMR) spectroscopy, electrochemical impedance analysis and, for the first time for non-irradiated membranes, by spectrophotometric analysis with Cr(III). The above-mentioned methods for application for DS assessment were compared. The aim of this study is to compare different methods used for the determination of the DS of SPEEK membranes before and after high-dose irradiation. It was observed that irradiated membranes presented a higher value of DS. The appearance of different new signals in 1H-NMR and FT-IR spectra of irradiated membranes indicated that the effects of radiation induced changes in the structure of SPEEK materials. The good correlation of Cr(III) absorption and SPEEK DS up to 80% indicates that the spectrophotometric method is a comparable tool for the characterization of SPEEK membranes.

Gamma irradiation synthesis and modification of palladium supported on graphene oxide as oxygen reduction reaction electrocatalyst

This work aims to investigate the preparation of palladium (Pd) particles on graphene oxide (GO) support via gamma radiolysis and to study their electrochemical activity towards the oxygen reduction reaction (ORR). The results show that the Pd precursor concentration used in the preparation process influences the loading, size, and distribution of the Pd particles. The electrochemical analysis shows that the Pd/GO samples synthesized through gamma radiolysis exhibit excellent activity toward ORR. Additionally, the gamma irradiation used in the synthesis process shows beneficial effects on the Pd/GO. High gamma irradiation doses increase the electron transfer number and reduce the peroxide yield of the Pd/GO.

Effect of gamma irradiation treatment on microstructure, water mobility, flavor, sensory and quality properties of smoked chicken breast.

Effect of gamma irradiation on quality, flavor and sensory properties of smoked chicken breasts were investigated. Results indicated irradiation doses >3kGy were effective for sterilization, while also produced a significant effect on overall quality of smoked chicken breast. Irradiation treatment could inhibit protein oxidation and accelerate lipid oxidation of smoked chicken breasts. High irradiation doses could increase the instability of free and bound water, as well as increase muscle fiber gap and juice loss significantly. Irradiation treatment also promoted free fatty acids and taste-presenting nucleotides degradation, effectively increased fresh-tasting amino acids contents and decreased bitter and sweet-tasting amino acids contents. The types and relative contents of volatiles, especially aldehydes, alcohols, aromatic hydrocarbons, and phenolic compounds, also changed after irradiation, while tartaric, pyruvic, and malic acids decreased. Results obtained can provide valuable reference data for improving the quality and flavor of smoked chicken breasts using gamma irradiation technology.

Revision Rates After Primary Allograft ACL Reconstruction by Allograft Tissue Type in Older Patients.

While there is extensive literature on the use of allograft versus autograft in anterior cruciate ligament (ACL) reconstruction, there is limited clinical evidence to guide the surgeon in choice of allograft tissue type. To assess the revision rate after primary ACL reconstruction with allograft and to compare revision rates based on allograft tissue type and characteristics. Cohort study; Level of evidence, 3. Patients who underwent primary allograft ACL reconstructions at a single academic institution between 2015 and 2019 and who had minimum 2-year follow-up were included. Exclusion criteria were missing surgical or allograft tissue type data. Demographics, operative details, and subsequent surgical procedures were collected. Allograft details included graft tissue type (Achilles, bone-patellar tendon-bone [BTB], tibialis anterior or posterior, semitendinosus, unspecified soft tissue), allograft category (all-soft tissue vs bone block), donor age, irradiation duration and intensity, and chemical cleansing process. Revision rates were calculated and compared by allograft characteristics. Included were 418 patients (age, 39 ± 12 years; body mass index, 30 ± 9 kg/m2). The revision rate was 3% (11/418) at a mean follow-up of 4.9 ± 1.4 years. There were no differences in revision rate according to allograft tissue type across Achilles tendon (3%; 3/95), BTB (5%; 3/58), tibialis anterior or posterior (3%; 5/162), semitendinosus (0%; 0/46), or unspecified soft tissue (0%; 0/57) (P = .35). There was no difference in revision rate between all-soft tissue versus bone block allograft (6/283 [2%] vs 5/135 [4%], respectively; P = .34). Of the 51% of grafts with irradiation data, all grafts were irradiated, with levels varying from 1.5 to 2.7 Mrad and 82% of grafts having levels of <2.0 Mrad. There was no difference in revision rate between the low-dose and medium-to high-dose irradiation cohorts (4% vs 6%, respectively; P = .64). Similarly low (0%-6%) revision rates after primary ACL reconstruction were seen regardless of allograft tissue type, bone block versus all-soft tissue allograft, and sterilization technique in 418 patients with mean age of 39 years. Surgeons may consider appropriately processed allograft tissue with or without bone block when indicating ACL reconstruction in older patients.