Radiation-induced conductivity in polymers under pulsed and long-time small-signal irradiations combined to determine their step-function response

2019 ◽  
Vol 126 (9) ◽  
pp. 095501 ◽  
Author(s):  
Andrey Tyutnev ◽  
Vladimir Saenko ◽  
Renat Ikhsanov ◽  
Evgenii Krouk
Keyword(s):  
Step Function ◽  
Small Signal ◽  
Long Time ◽  
Radiation Induced

scholarly journals Theoretical Analysis of the Radiation-Induced Conductivity in Polymers Exposed to Pulsed and Continuous Electron Beams

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 628 ◽  
Author(s):  
Andrey P. Tyutnev ◽  
Vladimir S. Saenko ◽  
Aleksey D. Zhadov ◽  
Dmitriy A. Abrameshin
Keyword(s):  
Electron Beam ◽  
Theoretical Analysis ◽  
Energy Distribution ◽  
Electron Beams ◽  
Small Signal ◽  
Deep Traps ◽  
Multiple Trapping ◽  
Long Time ◽  
Radiation Induced ◽  
Doped Polymers

We have performed comparative numerical calculations using a multiple trapping (MT) formalism with an exponential and an aggregate two-exponential trap distributions for describing two mostly used experimental setups for studying the radiation-induced conductivity (RIC) and the time-of-flight (TOF) effects. Computations have been done for pulsed and long-time electron-beam irradiations in a small-signal regime. Predictions of these two approaches differ appreciably in both setups. The classical MT approach proved very popular in photoconductive polymers generally and in molecularly doped polymers in particular, while a newly proposed complex MT worked well in common polymers. It has been shown that the complex MT successfully accounts for the presence of inherent deep traps, which may or may not have an energy distribution.

scholarly journals CBIO-11. NOVEL THERAPY TO TARGET PR-RECURRENT GLIOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii17-ii18
Author(s):  
Masum Rahman ◽  
Ian E Olson ◽  
Rehan Saber ◽  
Jibo Zhang ◽  
Lucas P Carlstrom ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Tumor Recurrence ◽  
Primary Brain Tumor ◽  
Differential Sensitivity ◽  
Proliferating Cells ◽  
Novel Therapy ◽  
Conventional Radiation ◽  
Long Time ◽  
Radiation Induced

Abstract BACKGROUND Glioblastoma is a fatal infiltrative primary brain tumor, and standard care includes maximal safe surgical resection followed by radiation and Temozolomide (TMZ). Therapy-resistant residual cells persist in a latent state a long time before inevitable recurrence. Conventional radiation and Temozolomide (TMZ) treatment cause oxidative stress and DNA damage resulting senescent-like state of cell-cycle arrest. However, increasing evidence demonstrates escaping senescence leads to tumor recurrence. Thus, the ablation of senescent tumor cells after chemoradiation may be an avenue to limit tumor recurrence. METHODS 100uM TMZ for 7days or 10-20Gy radiation (cesium gamma radiator) was used for senescence induction in human glioblastoma in vitro and confirmed by SA-Beta gal staining and PCR. Replication arrest assessed by automated quantification of cellular confluence (Thermo Scientific Series 8000 WJ Incubator). We evaluated the IC50 for several senolytics targeting multiple SCAPs, including Dasatinib, Quercetin, AMG-232, Fisetin, Onalespib, Navitoclax, and A1331852, and in senescent vs. proliferating cells. RESULTS Among the senolytic tested, the Bcl-XL inhibitors A1331852 and Navitoclax both shown senolytic effect by selectively killing radiated, senescent tumor cells at lower concentrations as compared to 0Gy treated non-senescent cells. Across 12 GBM cell lines, IC50 for senescent cells was 6–500 times lower than non-senescent GBM(p< 0.005). Such differential sensitivity to Bcl-XL inhibition after radiation has also observed by BCL-XL knockdown in radiated glioma. CONCLUSION These findings suggest the potential to harness radiation-induced biology to ablate surviving quiescent cells and demonstrate Bcl-XL dependency as a potential vulnerability of surviving tumor cells after exposure to chemoradiation.

scholarly journals Refined long-time asymptotics for Fisher–KPP fronts

2019 ◽  
Vol 21 (07) ◽  
pp. 1850072 ◽  
Author(s):  
James Nolen ◽  
Jean-Michel Roquejoffre ◽  
Lenya Ryzhik
Keyword(s):  
Travelling Waves ◽  
American Mathematical Society ◽  
Front Propagation ◽  
Step Function ◽  
Kolmogorov Equation ◽  
Compact Set ◽  
Kpp Equation ◽  
Branching Brownian Motion ◽  
Long Time ◽  
Unstable States

We study the one-dimensional Fisher–KPP equation, with an initial condition [Formula: see text] that coincides with the step function except on a compact set. A well-known result of Bramson in [Maximal displacement of branching Brownian motion, Comm. Pure Appl. Math. 31 (1978) 531–581; Convergence of Solutions of the Kolmogorov Equation to Travelling Waves (American Mathematical Society, Providence, RI, 1983)] states that, as [Formula: see text], the solution converges to a traveling wave located at the position [Formula: see text], with the shift [Formula: see text] that depends on [Formula: see text]. Ebert and Van Saarloos have formally derived in [Front propagation into unstable states: Universal algebraic convergence towards uniformly translating pulled fronts, Phys. D 146 (2000) 1–99; Front propagation into unstable states, Phys. Rep. 386 (2003) 29–222] a correction to the Bramson shift, arguing that [Formula: see text]. Here, we prove that this result does hold, with an error term of the size [Formula: see text], for any [Formula: see text]. The interesting aspect of this asymptotics is that the coefficient in front of the [Formula: see text]-term does not depend on [Formula: see text].

Experiments on Dispersive Pulse Propagation in Laminated Composites and Comparison With Theory

1969 ◽  
Vol 36 (3) ◽  
pp. 485-490 ◽  
Author(s):  
J. S. Whittier ◽  
J. C. Peck
Keyword(s):  
Pulse Propagation ◽  
Laminated Composites ◽  
Rear Surface ◽  
Step Function ◽  
Surface Velocity ◽  
Flat Plates ◽  
Theoretical Predictions ◽  
Long Time ◽  
Capacitance Gauge ◽  
High Degree

Transient stress-wave experiments on laminated composites are described, and the results are compared with theoretical predictions. The composites are laminated from alternating layers of high and low-modulus material, which cause a high degree of geometric dispersion of waves propagating in the composite. Experiments were conducted in which waves propagated parallel to the laminations. Flat plates were subjected on one face to a uniform pressure with step-function time dependence induced by a gas-dynamic shock wave. Under this loading, the central portion of the specimen initially responds as if it were laterally unbounded. The average velocity over a 3/8-in-dia area of the backface of the plate was measured with a capacitance gauge. The results are in good agreement with theoretical predictions made with a long-time asymptotic approximation called the head-of-the-pulse approximation. The theory isolates the dominant character of the response and predicts timing and amplitude of oscillations in normalized rear surface velocity within a few percent.

scholarly journals Dispersive fractalisation in linear and nonlinear Fermi–Pasta–Ulam–Tsingou lattices

2021 ◽  
pp. 1-26
Author(s):  
PETER J. OLVER ◽  
ARI STERN
Keyword(s):  
Initial Conditions ◽  
Step Function ◽  
Continuum Models ◽  
Time Intervals ◽  
Piecewise Constant ◽  
Periodic Linear ◽  
Long Time ◽  
Nonlinear Force ◽  
Linear And Nonlinear ◽  
Nonlinear Continuum

We investigate, both analytically and numerically, dispersive fractalisation and quantisation of solutions to periodic linear and nonlinear Fermi–Pasta–Ulam–Tsingou systems. When subject to periodic boundary conditions and discontinuous initial conditions, e.g., a step function, both the linearised and nonlinear continuum models for FPUT exhibit fractal solution profiles at irrational times (as determined by the coefficients and the length of the interval) and quantised profiles (piecewise constant or perturbations thereof) at rational times. We observe a similar effect in the linearised FPUT chain at times t where these models have validity, namely t = O(h−2), where h is proportional to the intermass spacing or, equivalently, the reciprocal of the number of masses. For nonlinear periodic FPUT systems, our numerical results suggest a somewhat similar behaviour in the presence of small nonlinearities, which disappears as the nonlinear force increases in magnitude. However, these phenomena are manifested on very long time intervals, posing a severe challenge for numerical integration as the number of masses increases. Even with the high-order splitting methods used here, our numerical investigations are limited to nonlinear FPUT chains with a smaller number of masses than would be needed to resolve this question unambiguously.

scholarly journals RONC-18. ANALYSIS OF BRAIN TUMOR INDUCED BY IRRADIATION IN CHILDHOOD - A SINGLE INSTITUTIONAL ANALYSIS

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii458-iii459
Author(s):  
Takashi Sano ◽  
Kaoru Tamura ◽  
Masae Kuroha ◽  
Kazutaka Sumita ◽  
Yukika Arai ◽  
...  
Keyword(s):  
Brain Tumor ◽  
Brain Tumors ◽  
Irradiation Dose ◽  
Clinical Characteristics ◽  
Cranial Irradiation ◽  
Surgical Removal ◽  
Long Term Follow Up ◽  
Long Time ◽  
Radiation Induced

Abstract BACKGROUND Radiation-induced brain tumors are rare tumors that appear during long-term follow-up after radiation therapy. Children are at greater risk for radiation -induced brain tumors than adults. The clinical characteristics of radiation-induced brain tumor treated at our hospital were retrospectively examined. PATIENTS AND METHODS Clinical characteristics of seven radiation-induced brain tumors that developed in 6 patients irradiated in their childhood at our hospital were analyzed. The background disease, age at irradiation, irradiation dose, period from irradiation to onset, pathological diagnosis, and treatment for radiation-induced brain tumor were examined. RESULTS Background diseases for irradiation were leukemia in 3 patients, germinoma in 2, medulloblastoma in 1, and the average cranial irradiation dose was 23.2 Gy. The patients tended to be young at irradiation (2–17 yeays; median:4 years old). The time between irradiation and the onset of radiation-induced brain tumors ranged from 9.5 to 39.1 years (median:28 years). Radiation-induced brain tumors comprised 6 meningioma（grade I:5, grade II:1）and 1 high-grade gliomas. All patients underwent surgical removal of the radiation-induced brain tumors and 2 received additional irradiation. During a median of 5.3 years of follow-up after the diagnosis of radiation-induced brain tumors, 2 underwent second surgery, while the remaining 4 have no recurrence. DISCUSSION: In most cases, radiation-induced brain tumors occur for a long time after irradiation in childhood. Monitoring of radiation-induced brain tumors as well as primary tumor recurrence was considered important.

scholarly journals Radiation resistance of borosilicate glass to beta and gamma radiation evaluated using the accelerated proton method

2021 ◽  
Vol 14 (1) ◽  
pp. 8-18
Author(s):  
A. S. Aloy ◽  
◽  
N. V. Kovalev ◽  
A. M. Prokoshin ◽  
N. F. Karpovich ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Borosilicate Glass ◽  
Chemical Properties ◽  
High Level Waste ◽  
Time Period ◽  
Long Time ◽  
Radiation Induced ◽  
Intermediate Storage ◽  
High Level ◽  
Physical And Chemical

Preservation of the main physical and chemical properties of vitrified high-level waste over a long-time period under the influence of heavy radiation exposure is considered as an essential criterion for its quality assessment used to demonstrate the safety of intermediate storage under controlled conditions and subsequent final disposal of the waste. Earlier calculations covering a time period of up to 104 years allowed to identify the maximum beta- and gamma-radiation induced dose loads for borosilicate glass (BSS) of a basic composition specifically designed to vitrify liquid HLW from ODC MCC [1]. This study evaluates potential feasibility of applying an accelerated proton beam to simulate radiation damage according to the type of beta-gamma effects produced on the BSS and investigates the consequences of such effects on its properties which is seen as a distinctive feature of this research.

scholarly journals Scarred Lung. An Update on Radiation-Induced Pulmonary Fibrosis

2021 ◽  
Vol 7 ◽  
Author(s):  
Natalia Jarzebska ◽  
Ekaterina S. Karetnikova ◽  
Alexander G. Markov ◽  
Michael Kasper ◽  
Roman N. Rodionov ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Fibrosis ◽  
Lung Fibrosis ◽  
Treatment Options ◽  
Inflammatory Cells ◽  
Oxygen Species ◽  
Current State ◽  
Complex Process ◽  
Long Time ◽  
Radiation Induced

Radiation-induced pulmonary fibrosis is a common severe long-time complication of radiation therapy for tumors of the thorax. Current therapeutic options used in the clinic include only supportive managements strategies, such as anti-inflammatory treatment using steroids, their efficacy, however, is far from being satisfactory. Recent studies have demonstrated that the development of lung fibrosis is a dynamic and complex process, involving the release of reactive oxygen species, activation of Toll-like receptors, recruitment of inflammatory cells, excessive production of nitric oxide and production of collagen by activated myofibroblasts. In this review we summarized the current state of knowledge on the pathophysiological processes leading to the development of lung fibrosis and we also discussed the possible treatment options.

scholarly journals Radiation-induced separation and accumulation of electric charge in supercapacitors

2018 ◽  
Vol 4 (3) ◽  
pp. 163-166 ◽  
Author(s):  
Vladimir Stepanov ◽  
Vladimir Chernov ◽  
Yury Parshikov ◽  
Viktor Lebedev ◽  
Yevgeny Kharanzhevsky
Keyword(s):  
Electric Charge ◽  
Absorbed Dose ◽  
Radioactive Isotopes ◽  
Asymmetric Supercapacitors ◽  
Carbon Particles ◽  
Pulsed Reactor ◽  
Long Time ◽  
Radiation Induced ◽  
Electrical Layer ◽  
Post Radiation

In current sources with a radioactive isotope (CSRI), nuclear energy is directly converted into electricity due to the separation of electric charges during the decay of radioactive isotopes. It was previously shown that asymmetric supercapacitors can be used as CSRI prototypes if, after being exposed to pulsed reactor irradiation, the electric charge on their plates increases to several coulombs as a result of internal induced activity. In this paper, the electric charge separation and accumulation in supercapacitors were studied directly in the process of neutron irradiation. The study was focused on the electrophysical characteristics of cylindrical supercapacitors with an organic electrolyte produced by JSC “ELEKOND”. A comparison of symmetric and asymmetric supercapacitors showed that an effective charge accumulation occurs in the asymmetric capacitors: it is independent of the neutron flux density and determined by the absorbed radiation dose. The electrical voltage between the plates of a symmetrical supercapacitor with a capacity of 100 F during irradiation up to an absorbed dose of 50 Gy reaches 1.24 mV. When asymmetric supercapacitors are irradiated with the same dose, a significant increase in the potential difference up to 1.15 V is observed during irradiation and for a long time afterwards (1.5·105 s) due to the electric charge redistribution (~ 5·10–3 C) in the electrolyte and carbon particles with the formation of a double electrical layer. The post-radiation increase in the capacity of asymmetric supercapacitors is ~ 5 mF.

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