scholarly journals Radiation-Induced Helium Bubbles in Metals

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1036 ◽  
Author(s):  
Shi-Hao Li ◽  
Jing-Ting Li ◽  
Wei-Zhong Han
Keyword(s):  
Nuclear Reactors ◽  
Bubble Nucleation ◽  
High Dose ◽  
Metallic Multilayers ◽  
Helium Bubbles ◽  
The Past ◽  
Particle Irradiation ◽  
Radiation Induced ◽  
Radiation Tolerant ◽  
Strength And Ductility

Helium (He) bubbles are typical radiation defects in structural materials in nuclear reactors after high dose energetic particle irradiation. In the past decades, extensive studies have been conducted to explore the dynamic evolution of He bubbles under various conditions and to investigate He-induced hardening and embrittlement. In this review, we summarize the current understanding of the behavior of He bubbles in metals; overview the mechanisms of He bubble nucleation, growth, and coarsening; introduce the latest methods of He control by using interfaces in nanocrystalline metals and metallic multilayers; analyze the effects of He bubbles on strength and ductility of metals; and point out some remaining questions related to He bubbles that are crucial for design of advanced radiation-tolerant materials.

scholarly journals Deviating from the pure MAX phase concept: Radiation-tolerant nanostructured dual-phase Cr2AlC

2021 ◽  
Vol 7 (13) ◽  
pp. eabf6771
Author(s):  
M. A. Tunes ◽  
M. Imtyazuddin ◽  
C. Kainz ◽  
S. Pogatscher ◽  
V.M. Vishnyakov
Keyword(s):  
Ion Beam ◽  
Extreme Environments ◽  
Secondary Phase ◽  
Bubble Nucleation ◽  
Max Phase ◽  
Dual Phase ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Radiation Induced ◽  
Radiation Tolerant

A dual-phase Cr2AlC material was synthesized using magnetron sputtering at a temperature of 648 K. A stoichiometric and nanocrystalline MAX phase matrix was observed along with the presence of spherical-shaped amorphous nano-zones as a secondary phase. The irradiation resistance of the material was assessed using a 300-keV Xe ion beam in situ within a transmission electron microscope up to 40 displacements per atom at 623 K: a condition that extrapolates the harmful environments of future fusion and fission nuclear reactors. At the maximum dose investigated, complete amorphization was not observed. Scanning transmission electron microscopy coupled with energy-dispersive x-ray revealed an association between swelling due to inert gas bubble nucleation and growth and radiation-induced segregation and clustering. Counterintuitively, the findings suggest that preexisting amorphous nano-zones can be beneficial to Cr2AlC MAX phase under extreme environments.

scholarly journals Impact of [18F]FDG-PET and [18F]FLT-PET-Parameters in Patients with Suspected Relapse of Irradiated Lung Cancer

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 279
Author(s):  
Tine N. Christensen ◽  
Seppo W. Langer ◽  
Gitte Persson ◽  
Klaus Richter Larsen ◽  
Annemarie G. Amtoft ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Overall Survival ◽  
Fdg Pet ◽  
Tumor Volume ◽  
High Dose ◽  
Flt Pet ◽  
Pet Ct ◽  
Radiation Induced ◽  
Fdg Pet Ct ◽  
Induced Changes

Radiation-induced changes may cause a non-malignant high 2-deoxy-2-[18F]fluoro-d-glucose (FDG)-uptake. The 3′-deoxy-3′-[18F]fluorothymidine (FLT)-PET/CT performs better in the differential diagnosis of inflammatory changes and lung lesions with a higher specificity than FDG-PET/CT. We investigated the association between post-radiotherapy FDG-PET-parameters, FLT-PET-parameters, and outcome. Sixty-one patients suspected for having a relapse after definitive radiotherapy for lung cancer were included. All the patients had FDG-PET/CT and FLT-PET/CT. FDG-PET- and FLT-PET-parameters were collected from within the irradiated high-dose volume (HDV) and from recurrent pulmonary lesions. For associations between PET-parameters and relapse status, respectively, the overall survival was analyzed. Thirty patients had a relapse, of these, 16 patients had a relapse within the HDV. FDG-SUVmax and FLT-SUVmax were higher in relapsed HDVs compared with non-relapsed HDVs (median FDG-SUVmax: 12.8 vs. 4.2; p < 0.001; median FLT-SUVmax 3.9 vs. 2.2; p < 0.001). A relapse within HDV had higher FDG-SUVpeak (median FDG-SUVpeak: 7.1 vs. 3.5; p = 0.014) and was larger (median metabolic tumor volume (MTV50%): 2.5 vs. 0.7; 0.014) than the relapsed lesions outside of HDV. The proliferative tumor volume (PTV50%) was prognostic for the overall survival (hazard ratio: 1.07 pr cm3 [1.01–1.13]; p = 0.014) in the univariate analysis, but not in the multivariate analysis. FDG-SUVmax and FLT-SUVmax may be helpful tools for differentiating the relapse from radiation-induced changes, however, they should not be used definitively for relapse detection.

scholarly journals Reduced High-Dose Radiation-Induced Residual Genotoxic Damage by Induction of Radioadaptive Response and Prophylactic Mild Dietary Restriction in Mice

Dose-Response ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 155932582098216
Author(s):  
Bing Wang ◽  
Kaoru Tanaka ◽  
Takanori Katsube ◽  
Kouichi Maruyama ◽  
Yasuharu Ninomiya ◽  
...  
Keyword(s):  
Dietary Restriction ◽  
High Dose ◽  
Cancer Treatments ◽  
Hematopoietic Stem ◽  
Beneficial Effects ◽  
Radiation Induced ◽  
Potential Strategy ◽  
Higher Doses

Radioadaptive response (RAR) describes a phenomenon in a variety of in vitro and in vivo systems that a low-dose of priming ionizing radiation (IR) reduces detrimental effects of a subsequent challenge IR at higher doses. Among in vivo investigations, studies using the mouse RAR model (Yonezawa Effect) showed that RAR could significantly extenuate high-dose IR-induced detrimental effects such as decrease of hematopoietic stem cells and progenitor cells, acute radiation hematopoietic syndrome, genotoxicity and genomic instability. Meanwhile, it has been demonstrated that diet intervention has a great impact on health, and dietary restriction shows beneficial effects on numerous diseases in animal models. In this work, by using the mouse RAR model and mild dietary restriction (MDR), we confirmed that combination of RAR and MDR could more efficiently reduce radiogenotoxic damage without significant change of the RAR phenotype. These findings suggested that MDR may share some common pathways with RAR to activate mechanisms consequently resulting in suppression of genotoxicity. As MDR could also increase resistance to chemotherapy and radiotherapy in normal cells, we propose that combination of MDR, RAR, and other cancer treatments (i.e., chemotherapy and radiotherapy) represent a potential strategy to increase the treatment efficacy and prevent IR risk in humans.

Treatment of Non-HIV Cryptosporidial Diarrhea with Azithromycin

1995 ◽  
Vol 29 (10) ◽  
pp. 991-993 ◽  
Author(s):  
Robert E Bessette ◽  
Guy W Amsden
Keyword(s):  
High Dose ◽  
Immunocompromised Patients ◽  
Excessive Weight Loss ◽  
The Past ◽  
Excessive Weight ◽  
Case Summary ◽  
Effective Option ◽  
Stool Cultures ◽  
Immunocompetent Patients

Objective: To report a patient with non-HIV-related cryptosporidial diarrhea who was treated effectively with a regimen of high-dose azithromycin therapy. Case Summary: A 42-year-old immunocompetent man contracted cryptosporidiosis from an ailing calf that he had purchased. He finally was admitted to the hospital because of excessive weight loss and profuse diarrhea. The patient was started on a course of high-dose azithromycin therapy and symptoms resolved within 48 hours. Follow-up stool cultures were negative for the parasite. Discussion: Although usually associated with immunocompromised patients, cryptosporidiosis occurs in immunocompetent hosts in a significant portion of the reported cases each year. Although self-limiting in most cases in this population, the disease can be severe at times and require treatment. Paromomycin therapy has been used in the past with good results. Although macrolides have had erratic effects against this parasite in the past, azithromycin (an azalide) demonstrated good efficacy in this patient. Conclusions: Azithromycin has demonstrated that it may be an effective option for the treatment of cryptosporidiosis in immunocompetent patients. Studies involving its use in immunocompromised patients are currently underway.

Exploring the Use of Alumina Nanofluid as Emergency Coolant for Nuclear Fuel Bundle

2018 ◽  
Vol 11 (2) ◽  
Author(s):  
A. S. Chinchole ◽  
Arnab Dasgupta ◽  
P. P. Kulkarni ◽  
D. K. Chandraker ◽  
A. K. Nayak
Keyword(s):  
Heat Transfer ◽  
Nuclear Fuel ◽  
Nuclear Reactor ◽  
Cooling System ◽  
Nuclear Reactors ◽  
Electrical Heating ◽  
High Dose ◽  
Potential Candidate ◽  
Alumina Nanofluid ◽  
Core Cooling

Abstract Nanofluids are suspensions of nanosized particles in any base fluid that show significant enhancement of their heat transfer properties at modest nanoparticle concentrations. Due to enhanced thermal properties at low nanoparticle concentration, it is a potential candidate for utilization in nuclear heat transfer applications. In the last decade, there have been few studies which indicate possible advantages of using nanofluids as a coolant in nuclear reactors during normal as well as accidental conditions. In continuation with these studies, the utilization of nanofluids as a viable candidate for emergency core cooling in nuclear reactors is explored in this paper by carrying out experiments in a scaled facility. The experiments carried out mainly focus on quenching behavior of a simulated nuclear fuel rod bundle by using 1% Alumina nanofluid as a coolant in emergency core cooling system (ECCS). In addition, its performance is compared with water. In the experiments, nuclear decay heat (from 1.5% to 2.6% reactor full power) is simulated through electrical heating. The present experiments show that, from heat transfer point of view, alumina nanofluids have a definite advantage over water as coolant for ECCS. Additionally, to assess the suitability of using nanofluids in reactors, their stability was investigated in radiation field. Our tests showed good stability even after very high dose of radiation, indicating the feasibility of their possible use in nuclear reactor heat transfer systems.

scholarly journals Spectrophotometric Study of ?-Irradiated PM-355

2009 ◽  
Vol 6 (3) ◽  
pp. 584-589
Author(s):  
Baghdad Science Journal
Keyword(s):  
Absorption Spectra ◽  
Calibration Curve ◽  
Linear Relation ◽  
Response Curve ◽  
Energy Gap ◽  
Linear Part ◽  
Absorbed Dose ◽  
Spectrophotometric Study ◽  
High Dose ◽  
Radiation Induced

The aim of the present work is concerned with the effect of ?-irradiation on PM-355 with absorbed dose of (30-160Mrad) range. This polymer is evaluated spectrophotometrically for use as high dose dosimeters. The absorption spectra of irradiated samples showed radiation induced absorption changes. There is an increment in absorption proportional with absorbed dose. This increment is attributed to interfaces traps which, are formed by irradiation. Calibration curve was drawn .The linear relation was found in calibration curve, and dosimeter range was determined from the linear part. The linearity in response curve suggested that PM-355 could be used as dosimeter within (30-160Mrad) rang. Energy gap shift was used as a second tool to determine the dosimeter range. It was found that PM-355 energy gap systematically decreasing with absorbed dose, and it could be used as a second tool to determine the dosimeter range.

Gamma Irradiation Effects on 4H-SiC MOS Capacitors and MOSFETs

2006 ◽  
Vol 527-529 ◽  
pp. 1063-1066 ◽  
Author(s):  
Ayayi Claude Ahyi ◽  
S.R. Wang ◽  
John R. Williams
Keyword(s):  
Field Effect ◽  
Gamma Dose ◽  
Interface Traps ◽  
Valence Band Edge ◽  
Field Effect Mobility ◽  
Irradiation Effects ◽  
Mos Capacitors ◽  
Channel Mobility ◽  
Radiation Induced ◽  
Radiation Tolerant

The effects of gamma radiation on field effect mobility and threshold voltage have been studied for lateral n-channel 4H-SiC MOSFETs passivated with nitric oxide. MOS capacitors (n and p) and n-channel lateral MOSFETs were irradiated unbiased (floating contacts) for a total gamma dose of 6.8Mrad (Si). The MOS capacitors were used to study the radiation-induced interface traps and fixed oxide charge that affect the performance of the MOSFETs. Radiationinduced interface traps were observed near the SiC valence band edge and just above mid-gap, and field effect channel mobility was reduced by 18-20% following irradiation. Even so, 4HMOSFETs appear to be more radiation tolerant than Si devices.

scholarly journals Acute Skin Damage and Late Radiation-Induced Fibrosis and Inflammation in Murine Ears after High-Dose Irradiation

Cancers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 727 ◽  
Author(s):  
Annique C. Dombrowsky ◽  
Jannis Schauer ◽  
Matthias Sammer ◽  
Andreas Blutke ◽  
Dietrich W. M. Walsh ◽  
...  
Keyword(s):  
Transforming Growth Factor Beta ◽  
Late Effects ◽  
Transforming Growth Factor ◽  
Scoring Systems ◽  
High Dose ◽  
Skin Damage ◽  
Fractional Dose ◽  
Radiation Induced ◽  
Tissue Alterations ◽  
Dose Dependent

The use of different scoring systems for radiation-induced toxicity limits comparability between studies. We examined dose-dependent tissue alterations following hypofractionated X-ray irradiation and evaluated their use as scoring criteria. Four dose fractions (0, 5, 10, 20, 30 Gy/fraction) were applied daily to ear pinnae. Acute effects (ear thickness, erythema, desquamation) were monitored for 92 days after fraction 1. Late effects (chronic inflammation, fibrosis) and the presence of transforming growth factor beta 1 (TGFβ1)-expressing cells were quantified on day 92. The maximum ear thickness displayed a significant positive correlation with fractional dose. Increased ear thickness and erythema occurred simultaneously, followed by desquamation from day 10 onwards. A significant dose-dependency was observed for the severity of erythema, but not for desquamation. After 4 × 20 and 4 × 30 Gy, inflammation was significantly increased on day 92, whereas fibrosis and the abundance of TGFβ1-expressing cells were only marginally increased after 4 × 30 Gy. Ear thickness significantly correlated with the severity of inflammation and fibrosis on day 92, but not with the number of TGFβ1-expressing cells. Fibrosis correlated significantly with inflammation and fractional dose. In conclusion, the parameter of ear thickness can be used as an objective, numerical and dose-dependent quantification criterion to characterize the severity of acute toxicity and allow for the prediction of late effects.

Global Approaches in Myeloma: Critical Trials That May Change Practice

2018 ◽  
pp. 656-661 ◽  
Author(s):  
Philippe Moreau ◽  
Cyrille Touzeau
Keyword(s):  
Multiple Myeloma ◽  
Clinical Trials ◽  
Therapeutic Strategies ◽  
New Drugs ◽  
High Dose ◽  
High Dose Therapy ◽  
The Past ◽  
Induced Changes ◽  
The Impact ◽  
Specific Section

The treatment of multiple myeloma (MM) has changed dramatically in the past decade with the introduction of new drugs into therapeutic strategies both in the frontline and relapse settings. With the availability of at least six different classes of agents that can be combined in doublet, triplet, or even quadruplet regimens and used together with high-dose therapy and autologous stem cell transplantation, the choice of the optimal strategy at diagnosis and at relapse represents a challenge for physicians. Also problematic is the lack of trials addressing questions, such as sequencing or the duration of maintenance. This review will focus on the results of recent clinical trials both in the frontline and relapse settings that have induced changes in clinical practice and will discuss the impact of important ongoing trials. A specific section will discuss therapeutic strategies when new drugs are not available.

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