Electron Beam Dose Research Articles

Evaluation of the effect of hyperthermia and electron radiation on prostate cancer stem cells

The aim of this study was to investigate the effect of hyperthermia, 6MeV electron radiation and combination of these treatments on cancer cell line DU145 in both monolayer culture and spheroids enriched for prostate cancer stem cells (CSCs). Flowcytometric analysis of the expression of molecular markers CD133+/CD44+ was carried out to determine the prostate CSCs in cell line DU145 grown as spheroids in serum-free medium. Following monolayer and spheroid culture, DU145 cells were treated with different doses of hyperthermia, electron beam and combination of them. The survival and self-renewing of the cells were evaluated by colony formation assay (CFA) and spheroid formation assay (SFA). Flowcytometry results indicated that the percentage of CD133+/CD44+ cells in spheroid culture was 13.9-fold higher than in the monolayer culture. The SFA showed significant difference between monolayer and spheroid culture for radiation treatment (6Gy) and hyperthermia (60 and 90min). The CFA showed significantly enhanced radiosensitivity in DU145 cells grown as monolayer as compared to spheroids, but no effect of hyperthermia. In contrast, for the combination of radiation and hyperthermia the results of CFA and SFA showed a reduced survival fraction in both cultures, with larger effects in monolayer than in spheroid culture. Thus, hyperthermia may be a promising approach in prostate cancer treatment that enhances the cytotoxic effect of electron radiation. Furthermore, determination and characterization of radioresistance and thermoresistance of CSCs in the prostate tumor is the key to develop more efficient therapeutic strategies.

Exciton diffusion coefficient measurement in ZnO nanowires under electron beam irradiation

In semiconductor nanowires (NWs) the exciton diffusion coefficient can be determined using a scanning electron microscope fitted with a cathodoluminescence system. High spatial and temporal resolution cathodoluminescence experiments are needed to measure independently the exciton diffusion length and lifetime in single NWs. However, both diffusion length and lifetime can be affected by the electron beam bombardment during observation and measurement. Thus, in this work the exciton lifetime in a ZnO NW is measured versus the electron beam dose (EBD) via a time-resolved cathodoluminescence experiment with a temporal resolution of 50 ps. The behavior of the measured exciton lifetime is consistent with our recent work on the EBD dependence of the exciton diffusion length in similar NWs investigated under comparable SEM conditions. Combining the two results, the exciton diffusion coefficient in ZnO is determined at room temperature and is found constant over the full span of EBD.

Effects of electron beam radiation dose on the compatibilization behaviour in recycled polypropylene/microcrystalline cellulose composites

The purpose of this research was to evaluate the influence of dose level of electron beam on the compatibilization behavior of recycled polypropylene (rPP) in rPP/microcrystalline cellulose (MCC) composites. Initially, the rPP was irradiated with various dose of electron beam (5 kGy up to 250 kGy) which then mixed with unirradiated rPP (u-rPP) at a ratio of 30:70 respectively. The composites were prepared by incorporating a series wt% of MCC fibers into rPP (u-rPP : i-rPP) using extruder and finally moulded with an injection moulding machine. The compatibility behavior of irradiated rPP (i-rPP) were analysed with mechanical tensile and thermal methods. The results of mechanical analysis showed great improvement in tensile modulus but an increase in radiation dosage gradually decreased this property. Nevertheless, the tensile strength exhibited a minor effect. The thermal stability of composites is lowered with increase in the absorbed dose, more significantly at higher content of MCC. Fracture surface observations reveal adhesion between the cellulose and rPP matrix.

Electron beam irradiation effect on critical heat flux in downward-facing flow boiling

In previous research on nuclear reactors, the effect of irradiation on heat transfer has rarely been studied. We investigated the electron beam irradiation effect on downward-facing flow boiling heat transfer and critical heat flux. All the critical heat flux values in flow boiling decreased after irradiation, particularly at low doses, whereas heat transfer coefficient almost remained the same. Low dose electron beam irradiation substantially increased the nucleation sites on the heated copper surface, and the critical heat flux was inversely related to the nucleation site density in downward-facing flow boiling.

Exploring the Influence of Methylene Diphenyl Diisocyanate as a Modifier for Ethylene Vinyl Acetate/Thermoplastic Polyurethane Blends

ABSTRACTEthylene vinyl acetate (EVA)/thermoplastic polyurethane (TPU) blend at various blend ratios has been modified via reactive processing with 4,4′-methylene diphenyl diisocyanate (MDI). Modification of the blends with even small amount of MDI shows significant improvement in physico-mechanical properties for EVA/TPU 50/50 and 30/70 blends, and it is also supported by the superior melt rheological behavior and dramatic improvement in oil resistance property. After the treatment of electron beam (dose range: 50–150 kGy), radiation crosslinked EVA/TPU (30:70) blend reveals further improvement in various properties. This particular material can find potential application as cable sheathing component.

Direct writing of gold nanostructures with an electron beam: On the way to pure nanostructures by combining optimized deposition with oxygen-plasma treatment.

This work presents a highly effective approach for the chemical purification of directly written 2D and 3D gold nanostructures suitable for plasmonics, biomolecule immobilisation, and nanoelectronics. Gold nano- and microstructures can be fabricated by one-step direct-write lithography process using focused electron beam induced deposition (FEBID). Typically, as-deposited gold nanostructures suffer from a low Au content and unacceptably high carbon contamination. We show that the undesirable carbon contamination can be diminished using a two-step process – a combination of optimized deposition followed by appropriate postdeposition cleaning. Starting from the common metal-organic precursor Me2-Au-tfac, it is demonstrated that the Au content in pristine FEBID nanostructures can be increased from 30 atom % to as much as 72 atom %, depending on the sustained electron beam dose. As a second step, oxygen-plasma treatment is established to further enhance the Au content in the structures, while preserving their morphology to a high degree. This two-step process represents a simple, feasible and high-throughput method for direct writing of purer gold nanostructures that can enable their future use for demanding applications.

Practical lookup tables for ensuring target coverage in a clinical setup for skin cancer electron therapy

AbstractAimTo create practical lookup tables containing percent depth dose (PDD) and profile parameters of electron beams and to demonstrate clinical application of the lookup tables to skin cancer treatment to ensure target coverage in a clinical setup.Materials and methodsFor 6 and 9 MeV electron energies, PDDs and profiles at clinically relevant depths [i.e., R95 (distal depth of 95% maximum dose), R90, R85 and R80] were measured in water at 100 cm source-to-surface distance for an 10×10 cm2 open field and circular cutouts with diameters of 4, 5, 6, 7 and 8 cm. Then PDD parameters along with profile parameters such as width of isodose lines and penumbra at the clinically relevant depths were determined. Output factors for the cutouts were measured at dmax in water and solid water.ResultsWith PDD and profile parameters, dosimetry lookup tables were generated. Based upon the lookup tables, target coverage at prescribed depths was retrospectively reviewed for three skin cancer cases. The lookup tables suggested larger cutouts for adequate target coverage.FindingsDosimetry lookup tables for electron beam therapy should include profile parameters at clinically relevant depths and be provided to clinicians to ensure target coverage in a clinical setup.

Correlation between structural and transport properties of electron beam irradiated PrMnO3 compounds

The structural, electrical, magnetic, and thermal properties of electron beam (EB) irradiated PrMnO3 manganites were investigated in the present communication. X-ray diffraction data reveals that all samples are single phased with orthorhombic distorted structure (Pbnm). Furthermore, the diffracted data are analyzed in detail using Rietveld refinement technique. It is observed that the EB dosage feebly disturbs the MnO6 octahedra. The electrical resistivity of all the samples exhibits semiconducting behavior. Small polaron hopping model is conveniently employed to investigate the semiconducting nature of the pristine as well as EB irradiated samples. The Seebeck coefficient (S) of the pristine as well as the irradiated samples exhibit large positive values at lower temperatures, signifying holes as the dominant charge carriers. The analysis of Seebeck coefficient data confirms that the small polaron hopping mechanism assists the thermoelectric transport property in the high temperature region. The magnetic measurements confirm the existence of paramagnetic (PM) to ferromagnetic (FM) behavior for the pristine and irradiated samples. In the lower temperature regime, coexistence of FM clusters and AFM matrix is dominating. Thus, the complex magnetic behavior of the compound has been explained in terms of rearrangement of antiferromagnetically coupled ionic moments.

Preparation and Characterization of Resorbable Bacterial Cellulose Membranes Treated by Electron Beam Irradiation for Guided Bone Regeneration.

Bacterial cellulose (BC) is an excellent biomaterial with many medical applications. In this study, resorbable BC membranes were prepared for guided bone regeneration (GBR) using an irradiation technique for applications in the dental field. Electron beam irradiation (EI) increases biodegradation by severing the glucose bonds of BC. BC membranes irradiated at 100 kGy or 300 kGy were used to determine optimal electron beam doses. Electron beam irradiated BC membranes (EI-BCMs) were evaluated by scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), and using wet tensile strength measurements. In addition, in vitro cell studies were conducted in order to confirm the cytocompatibility of EI-BCMs. Cell viabilities of NIH3T3 cells on 100k and 300k EI-BCMs (100 kGy and 300 kGy irradiated BC membranes) were significantly greater than on NI-BCMs after 3 and 7 days (p < 0.05). Bone regeneration by EI-BCMs and their biodegradabilities were also evaluated using in vivo rat calvarial defect models for 4 and 8 weeks. Histometric results showed 100k EI-BCMs exhibited significantly larger new bone area (NBA; %) than 300k EI-BCMs at 8 weeks after implantation (p < 0.05). Mechanical, chemical, and biological analyses showed EI-BCMs effectively interacted with cells and promoted bone regeneration.

Morphology control and mechanical properties of monoacrylates polymers prepared by UV and Electron Beam photopolymerization

The morphology and the mechanical properties of the polymer networks have been investigated under UV and electron beam irradiation based on the molecular weight distribution of the polymer chains. It has been observed that the molar mass and the length of the polymer chain have a major effect in determining the morphology and mechanical properties of the polymer. The morphology and the architecture of the polymer chains can be controlled by varying the intensity of the UV and electron beam doses during the photopolymerization.

Measurement of the influence of titanium hip prosthesis on therapeutic electron beam dose distributions in a novel pelvic phantom

PurposeTo investigate the degree of 18 and 22MeV electron beam dose perturbations caused by unilateral hip titanium (Ti) prosthesis. MethodsMeasurements were acquired using Gafchromic EBT2 film in a novel pelvic phantom made out of Nylon-12 slices in which a Ti-prosthesis is embedded. Dose perturbations were measured and compared using depth doses for 8×8, 10×10 and 11×11cm2 applicator-defined field sizes at 95cm source-surface-distance (SSD). Comparisons were also made between film data at 100cm SSD for a 10×10cm2 field and dose calculations made on CMS XiO treatment planning system utilizing the pencil beam algorithm. The extent of dose deviations caused by the Ti prosthesis based on film data was quantified through the dose enhancement factor (DEF), defined as the ratio of the dose influenced by the prosthesis and the unchanged beam. ResultsAt the interface between Nylon-12 and the Ti implant on the prosthesis entrance side, the dose increased to values of 21±1% and 23±1% for 18 and 22MeV electron beams, respectively. DEFs increased with increasing electron energy and field size, and were found to fall off quickly with distance from the nylon-prosthesis interface. A comparison of film and XiO depth dose data for 18 and 22MeV gave relative errors of 20% and 25%, respectively. ConclusionThis study outlines the lack of accuracy of the XiO TPS for electron planning in highly heterogeneous media. So a dosimetric error of 20–25% could influence clinical outcome.

Non-Fluorinated High Performance Pre-Irradiation Grafted Anion-Exchange Membranes

There have been a boom in the development of anion-exchange membranes (AEMs) for fuel cells (AEMFC) and water electrolyzers in recent years. These devices permit the use of a wider range of non-precious-metal electrocatalysts along with additional fuel flexibility (e.g. the use of N-containing fuels such as hydrazine). A significant tool for the production of AEMs is radiation induced graft polymerization. We have proved that a water-based, emulsion radiation graft polymerization of vinylbenzyl chloride (VBC) onto partially fluorinated ETFE film enhanced the degree of grafting compared to when an organic diluent was used. 1 A major challenge in handling ETFE-based radiation-grafted AEMs has always been their rather poor mechanical stability due to the radiation treatment. 2 Locally, fuel cell tests were not necessarily terminated due to chemical degradation but due to swelling stresses and membrane rupture. This study focuses on the emulsion-type radiation (peroxidation) grafting of VBC onto non-fluorinated LDPE films of 25 μm thickness using electron-beams (in air). VBC is an ideal grafting monomer as it contains both a polymerizable double bond and a reactive benzyl chloride group, the latter of which can be converted to positively charged anion-exchange groups on reaction with amines. ETFE with the same thickness, 25 μm, was grafted under identical conditions as the benchmark. An elevated electron-beam dose was required with the LDPE to obtain the desired grafting levels (cf. ETFE). The LDPE- and ETFE-based AEMs were characterized in terms of ion-exchange capacity (IEC), water uptakes and swelling, and in-plane conductivity. Raman microscopy of the AEM cross-sections was used to map the distribution of the graft component across the samples’ thicknesses (μm spacial resolution). The LDPE-AEMs exhibited enhanced mechanical stabilities (relative tensile stress–strain testing). A high-performance LDPE-AEM, with enhanced properties compared to the reference ETFE-AEM was evaluated in single H2/O2 fuel cell tests. The fuel cell performances were tested up to T = 80°C. The polarisation curves are presented in Fig. 1a. A significantly higher fuel cell performance was obtained with the LDPE-AEM. The enhancement is due to a combination of high anion conductivity and enhanced water management (facilitated water back transport from the anode to the cathode). Furthermore, the LDPE-AEM exhibited superior mechanical strength (cf. ETFE-AEM) even after alkali treatment (Fig. 1b). Figure 1. a) H2/O2 AEMFC performance at 80 °C (PtRu/C anodes and Pt/C cathodes, Pt loadings all 0.4±0.02 mg cm-2) and no gas back-pressurization. b) Tensile measurements on the LDPE- and ETFE-AEMs (before and after aqueous KOH (1 M) treatment at 80°C for 7 days). 1. L. Q. Wang, E. Magliocca, E. L. Cunningham, W. E. Mustain, S. D. Poynton, R. Escudero-Cid, M. M. Nasef, J. Ponce-González, R. Bance-Soualhi, R. C. T. Slade, D. K. Whelligan and J. R. Varcoe, Green Chemistry, 2017, 19, 831-843. 2. J. Huslage, T. Rager, B. Schnyder and A. Tsukada, Electrochim Acta, 2002, 48, 247-254. Figure 1

Benchmarking the minimum Electron Beam (eBeam) dose required for the sterilization of space foods

As manned space missions extend in length, the safety, nutrition, acceptability, and shelf life of space foods are of paramount importance to NASA. Since food and mealtimes play a key role in reducing stress and boredom of prolonged missions, the quality of food in terms of appearance, flavor, texture, and aroma can have significant psychological ramifications on astronaut performance. The FDA, which oversees space foods, currently requires a minimum dose of 44kGy for irradiated space foods. The underlying hypothesis was that commercial sterility of space foods could be achieved at a significantly lower dose, and this lowered dose would positively affect the shelf life of the product. Electron beam processed beef fajitas were used as an example NASA space food to benchmark the minimum eBeam dose required for sterility. A 15kGy dose was able to achieve an approximately 10log reduction in Shiga-toxin-producing Escherichia coli bacteria, and a 5log reduction in Clostridium sporogenes spores. Furthermore, accelerated shelf life testing (ASLT) to determine sensory and quality characteristics under various conditions was conducted. Using Multidimensional gas-chromatography–olfactometry–mass spectrometry (MDGC-O-MS), numerous volatiles were shown to be dependent on the dose applied to the product. Furthermore, concentrations of off –flavor aroma compounds such as dimethyl sulfide were decreased at the reduced 15kGy dose. The results suggest that the combination of conventional cooking combined with eBeam processing (15kGy) can achieve the safety and shelf-life objectives needed for long duration space-foods.

Unique shape memory behavior of polyolefinic blends with special reference to creep behavior, stress relaxation, and melt rheological study

Creep response, stress relaxation behavior, and melt rheological study of the shape memory polymer blend based on EOC‐EPDM has been studied in details. In this study, especially the effect of the crosslinks formation in presence of electron beam on the creep response, melt rheological study and stress relaxation behavior has been reported. With increase of electron beam dose, creep response becomes lower and the creep compliance value also comes down. Higher resistance creep response of the radiation crosslinked blends indicates the superior shape recovery behavior of the blends. Stress relaxation behavior of the crosslinked blend also shows the lower decay of stress value with time for higher radiation crosslinked blend. The lower relaxation ratio of the highly radiation crosslinked blend also supports the superior shape recovery behavior of the crosslinked blend. Apart from, melt rheological study shows the higher storage modulus value and higher complex viscosity of the radiation crosslinked blend which also supports the formation of higher crosslinked network structure. Tension set value also clearly indicates the better shape recovery behavior of the crosslinked blend. POLYM. ENG. SCI., 58:876–885, 2018. © 2017 Society of Plastics Engineers

Electron beam modified zinc phthalocyanine thin films for radiation dosimeter application

Present study deals with the effect of electron beam irradiation on electrical and gas sensing properties of zinc phthalocyanine (ZnPc) thin film prepared on flexible Biaxially Oriented Polyethylene Terephthalate (BOPET) sheet. The electron beam irradiation of ZnPc films were carried out using a 10MeV RF Linear accelerator, under different radiation dose levels from 1kGy to 30kGy. The pristine and irradiated films were characterized by using X-ray photoelectron spectroscopy, Atomic Force microscopy, UV–vis spectroscopy and X-ray diffraction. Samples irradiated in the dose range of 1–18kGy exhibit linear enhancement of electrical conductance due to increasing content of adsorbed oxygen. Beyond 18kGy the sample exhibit saturation in the content of adsorbed oxygen as well as in electrical conductance. The pristine ZnPc films exhibit excellent chemi-resistive response towards H2S gas in 1–20ppm range at room temperature. The response of the irradiated films decreases monotonically with increasing electron beam dose due to the strong binding of oxygen at the Zn sites. A plausible mechanism of electron beam induced modification of ZnPc films and its implication on charge transport as well as chemi-resistive gas sensing behavior are discussed. This work highlight the utilization of ZnPc thin films as potential radiation dosimeter based upon linear rise in electrical conductance.

Behaviour of advanced tritium breeder pebbles under simultaneous action of accelerated electrons and high temperature

Advanced lithium orthosilicate (Li4SiO4) pebbles with additions of lithium metatitanate (Li2TiO3) as a secondary phase are suggested as a potential source for tritium breeding in future nuclear fusion reactors. The advanced Li4SiO4 pebbles with different contents of Li2TiO3 were examined before and after simultaneous action of 5MeV accelerated electron beam (dose rate: up to 10MGyh−1) and high temperature (up to 1120K) in a dry argon atmosphere. The accumulated radiation-induced defects (RD) and radiolysis products (RP) were studied by electron spin resonance (ESR) spectrometry and thermally stimulated luminescence (TSL) technique. The phase transitions were studied with powder X-ray diffraction (p-XRD). The microstructure and mechanical strength of the pebbles, before and after irradiation, were investigated by scanning electron microscopy (SEM) and comprehensive crush load tests. The obtained results revealed that the irradiation temperature has a significant impact on the accumulation of RD and RP in the advanced Li4SiO4 pebbles, and with an increasing content of Li2TiO3, the concentration of accumulated paramagnetic RD and RP decreases. Major changes in the mechanical strength, microstructure and phase composition of the advanced pebbles were not detected after irradiation.

The Effect of Electron Beam Dosage in the Decomposition Behavior of Electrolytes Encapsulated Inside the Graphene Sheets Based on In Situ TEM Observation

The Effect of Electron Beam Dosage in the Decomposition Behavior of Electrolytes Encapsulated Inside the Graphene Sheets Based on <i>In Situ</i> TEM Observation

Behavior of nitrogen-related luminescence centers in laser-cut single-crystalline diamond under irradiation with keV electron beam

ABSTRACTWe have found that several nitrogen-related luminescence centers appear at 389 nm, 503 nm (H3 center), 575 nm (NV0 center), 637 nm (NV- center) in single-crystalline Ib diamond cut by means of a YAG laser irradiation process, followed by a suitable hydrogen microwave-plasma treatment, and that cathodoluminescence peaks related to these centers substantially change in intensity by irradiating the sample with 15-keV electron beam (EB). The relative number of 389-nm centers originating from a pair of a substitutional nitrogen atom and an adjacent interstitial carbon atom increased while the concentrations of the vacancy-related centers were reduced with increasing 15-keV EB doses. These facts indicate that both the process-induced self-interstitials and the vacancies in the diamond rather easily moved to more preferential positions to form their stabler defect states, being suggestive of possibility to control densities of NV and NV-related centers.

Influence of Electron Beam Irradiation on the Electrical and Optical Properties of InGaZnO Thin Film Transistor

The effects of electron beam(EB) irradiation on the electrical and optical properties of InGaZnO(IGZO) thin films fabricated using a sol-gel process were investigated. As the EB dose increased, the electrical characteristic of the IGZO TFTs changed from semiconductor to conductor, and the threshold voltage values shifted to the negative direction. X-ray photoelectron spectroscopy analysis of the O 1s core level showed that the relative area of oxygen vacancies increased from 14.68 to 19.08 % as the EB dose increased from 0 to 1.5 × 1016 electrons/cm2. In addition, spectroscopic ellipsometer analysis showed that the optical band gap varied from 3.39 to 3.46 eV with increasing EB dose. From the result of band alignment, it was confirmed that the Fermi level(EF) of the sample irradiated with 1.5 × 1016 electrons/cm2 was located at the closest position to the conduction band minimum(CBM) due to the increase of electron carrier concentration

Characterization of Water-Clear Polymeric Gels for Use as Radiotherapy Bolus

Our purpose was to investigate polymeric gels for use as a highly transparent radiotherapy bolus and determine the relevant physical and dosimetric properties. We first quantified tensile properties (maximum stress, strain, and Young modulus) for various polymeric gels, along with a commercial bolus product in order to illustrate the wide variety of potential materials. For a select polymeric gel with tensile properties similar to currently used radiotherapy bolus, we also evaluated mass and electron density, effective atomic number, optical transparency, and percent depth dose in clinical megavoltage photon and electron beams. For this polymeric gel, mass density was 872 ± 12 and 896 ± 13 g/cm3 when measured via weight/volume and computed tomography Hounsfield units, respectively. Electron density was 2.95 ± 0.04 ×1023 electrons/cm3. Adding fused silica (9% by weight) increases density to that of water. The ratio of the effective atomic number to that of water without and with added silica was 0.780 and 0.835 at 1 MeV, 0.767 and 0.826 at 6 MeV, and 0.746 and 0.809 at 20 MeV. Percent depth dose for 6 MV photons was within 2% of water within the first 2.5 cm and after scaling by the density coincided within 1% out to >7 cm. For 6 and 20 MeV electrons, after scaling for density D80% was within 1.3 and 1.5 mm of water, respectively. The high transparency and mechanical flexibility of polymeric gels indicate potential for use as a radiotherapy bolus; differences in density from water may be managed via either using “water equivalent thickness” or by incorporating fused silica into the material.