E-beam Irradiation Research Articles

Extreme UV Resist Exhibiting Synergism between Chemical and Physical Crosslinking Mechanisms.

Carbon-fluorine bonds in fluorinated molecules can undergo homolytic cleavage reactions when electrons are injected, and the resulting radicals combine to form network structures characterized by reduced solubility. This crosslinking chemistry suggests a new category of patterning materials that function under electron beam (e-beam) and extreme ultraviolet (EUV) lithographic conditions. Although this chemistry enables the production of 50 nm or smaller-sized features of simple fluoroalkylated polymers, it is limited by the need for relatively large amounts of irradiation energy to achieve required solubility changes. Therefore, this study was undertaken to devise a sensitivity-enhancing strategy based on a synergistic combination of radical crosslinking and hydrogen-bonding interactions between highly fluoroalkylated copolymers. An alternating copolymer was synthesized using tert-butoxystyrene and a fluoroalkylated maleimide, the former of which produces active hydrogens through catalytic acidolysis reactions. When the polymer was blended with a catalytic amount of a photoacid generator and subjected to lithographic patterning tests under e-beam and EUV irradiation, the deprotection reactions of tert-butoxy moieties proceeded at room temperature and led to a solubility decrease. We presume the small number of hydroxyl moieties produced formed an intermolecular hydrogen-bonding network, which acted synergistically with the covalent crosslinks generated by C-F bonds. When 30 nm features of copolymer thin films were fabricated by EUV lithography, sensitivity was improved by 25-34% without significant deterioration of pattern quality, especially line-edge roughness. These results demonstrate that EUV resists with improved patterning capabilities can be achieved by combining catalytic acidolysis reactions and noncatalytic crosslinking chemistry.

Conceptual design of hybrid target for molybdenum-99 production based on heavywater

Molybdenum-99 (99Mo) is used for preparing Technetium-99 m (99mTc), which is the most widely used isotope in nuclear medicine. In this work, a study for 99Mo production based on a high-power electron accelerator has been performed as an alternative approach to produce 99mTc. In this study, Monte Carlo MCNPX2.6 code has been used to examine a novel idea of simultaneous hybrid production of 99Mo via both photoneutron and neutron capture reactions using an electron accelerator in heavy water tank. It is expected that this conceptual design including an arrangement of metallic plates of 100Mo and 98Mo produces total activity of 97.5 Ci at the end of 20-h continuous e-beam irradiation (30 MeV, 10 mA).

Effect of E-beam irradiation on the qualitative attributes of shrimp (Penaeus vannamei)

As a non-thermal food processing technology, Electron beam (E-beam) irradiation has been used to enhance microbial safety by deactivating unwanted spoilage and pathogenic microorganisms in food industry. This study evaluated the effects of E-beam irradiation at doses killing SARS-COV-2 on qualities and sensory attributes. The results showed that irradiation caused little effect on the proximate composition, amino acid content, texture, and sensory attributes (P > 0.05). However, E-beam increased TBARS (Thiobarbituric acid reactive substances) and lowered vitamin E content in dose-dependently. Irradiation up to 10 kGy significantly decreased unsaturated fatty acid (UFA) content and inhibited the increase in TVB-N (The total volatile basic nitrogen) while reducing cohesiveness and chewiness (P < 0.05). E-beam irradiation with 7–10 kGy caused greater ΔE values (ΔE > 5) via the significant increase of b*, accompanied by big visual difference in shrimp (P < 0.05). A dose of 4 kGy E-beam irradiation was recommended without altering its physicochemical properties and sensory attributes.

Investigating the role and mechanism of water in E-beam modified sweet potato starch: Multi-scale structure, physicochemical properties, and in vitro digestibility

Aiming to investigate the role and mechanism of the effect of water on the structural, physicochemical, and in vitro digestible properties of starch during irradiation processing. This work used water pretreatment of sweet potato starch (12%, 25%, 50%, 75% and 100% water content) and then modification by E-beam (6, 12 and 24 kGy). The results showed that E-beam treatment preserved the polarization cross, growth rings, crystal types and FT-IR patterns of sweet potato starch. Also, E-beam induced the water molecule activation and free radical production, thus promoting starch degradation. Moreover, the short-range ordered structure, relative crystallinity, molecular weight, long-chain proportion, ΔH, viscosity and swelling power of starch decreased with increasing E-beam irradiation dose. In contrast, the short-chain proportion, solubility, and resistant starch content were improved. In addition, a synergistic effect was found between the water pretreatment and E-beam, i.e., the higher the water content of the starch, the deeper the modification by E-beam. Results obtained in this study can partially elucidate the role of water content in E-beam-modified starch and provide a basis for E-beam treatment of starch-based foods under different water levels.

Possibility of using ionizing radiation treated sludge from drinking water treatment plant as fertilizer in agriculture: Effects of aging

Using ionizing radiation in treating waste sludge from a drinking water treatment plant is a well-known technique. Sludge treated with ionizing radiation can be used as fertilizer in agriculture. In this paper, the effects of aging on the physicochemical characteristics, the content of microorganisms, molds, acrylamide, heavy metal concentration, and total nutrient content in waste sludge treated with e-beam and gamma irradiation were investigated. The possibility of using treated sludge as a fertilizer in agriculture was evaluated. It has been shown that the content of acrylamide in treated sludge after 15 months of storage does not exceed the limits for sludge to be used as fertilizer. If the sludge is stored in closed bags in a dark place, aging does not increase total microorganisms and molds. The research also showed that the sludge's physicochemical characteristics treated in this way do not decrease under the influence of aging. Finally, it has been shown that aging does not change the concentration of heavy metals and total nutrients in sludge treated by ionizing irradiation.

Effects of specific doses of E-beam irradiation which inactivated SARS-CoV-2 on the nutrition and quality of Atlantic salmon

The contamination of Atlantic salmon with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has impeded the development of the cold-chain food industry and posed possible risks to the population. Electron beam (E-beam) irradiation under 2, 4, 7, and 10 kGy can effectively inactivate SARS-CoV-2 in cold-chain seafood. However, there are few statistics about the quality changes of salmon exposed to these irradiation dosages. This work demonstrated that E-beam irradiation at dosages capable of killing SARS-CoV-2 induced lipid oxidation, decreased vitamin A content, and increased some amino acids and ash content. In addition, irradiation altered the textural features of salmon, such as its hardness, resilience, cohesiveness, and chewiness. The irradiation considerably affected the L*, a*, and b* values of salmon, with the L* value increasing and a*, b* values decreasing. There was no significant difference in the sensory evaluation of control and irradiated salmon. It was shown that irradiation with 2−7 kGy E-beam did not significantly degrade quality. The inactivation of SARS-CoV-2 in salmon is advised at a dose of 2 kGy.

Evaluation of Riboflavin as an enhancer for X-ray and EBeam irradiation treatment of Tulane virus

Ionizing technologies rely on high doses of irradiation to achieve 5-log reduction of foodborne viruses. We hypothesized that riboflavin (vitamin B2), a singlet oxygen enhancer could synergize the virucidal effects of electron beam (eBeam) and X-ray doses by using Tulane virus as a model virus. Concentrations of up to 1% w/v riboflavin were evaluated against 1 kGy X-ray treatments. Also 0.1% riboflavin was evaluated against eBeam treatments up to 10 kGy. The results showed that riboflavin did not enhance the sensitivity of Tulane virus to either eBeam or X-ray treatments.

Time-Resolved Dynamic Crystallization at Liquid/Vapor Interface

We report the behavior of nanodroplets containing aqueous NaOH solutions of different concentrations, visualized using transmission electron microscopy (TEM). Under e-beam irradiation, highly charged aqueous NaOH droplets dewet with edge crystallization before erupting into satellite nanodroplets. For the first time, we observe dynamic nanocrystal precipitation from nanodroplet followed by redissolution in a periodic manner. Time-resolved images show that the crystalline precipitates occur predominantly in two distinct geometric shapes─hexagonal and square. Through structural, elemental, and morphological analyses, we deduce that the crystalline precipitate is monohydrate NaOH·H2O, whose orthorhombic structure forms the underlying basis for the evolved crystalline shapes. Through numerical simulations, we show how the observed preferential orientation of the crystal precipitate depends on crystal morphology and relative droplet–crystal size, but not on electrical forces, which govern droplet deformations. Together, our results reveal strong dynamics at the interface, including ionic chemistry, nanoscale physics, and hydrodynamics.

Electron Beam as Straightener to De‐Wrinkle Large 2D Black Phosphorus Flake: An In Situ TEM Monitoring (Adv. Mater. Interfaces 32/2022)

De-Wrinkling of 2D Materials In article number 2201320, Manpreet Kaur, Kiran S. Hazra, and colleagues report on electron beam based straightening of 2D materials, a step towards materializing their practicality for next generation electronics. In-situ TEM monitoring demonstrates flattening of 2D layers is synchronous with the de-stressing of lattice under e-beam irradiation, and the declination-ridden lattice can be evolved into the uniformly spaced parallel lattice planes in a controlled manner.

A dual-drive mode MEMS device for in-situ static/dynamic electro-mechanical characterization of nanomaterials

A novel dual-drive MEMS device integrated with both a thermal actuator and an electrostatic actuator is proposed and fabricated, which realizes the convenient in-situ electro-mechanical test for nanomaterials. The drive mode can be agilely selected to analyze different mechanical properties and the accuracy of the test can be verified by self-contrast of the two driving modes. Using the nanomanipulator as the transfer method, coupled mechanical and electrical tests are carried out for TiO2 nanowires. The measured Young's modulus of the nanowire in the two driving modes are 78.2 GPa and 85.6 GPa, and the fracture stress are 562 MPa and 584 MPa, respectively. The electron beam (e-beam) irradiation effect on electrical properties is investigated. Meanwhile, the resistance of the nanowires is determined as a variable of strain, which demonstrates the changes in resistance are the result of the loaded strains. The resistance decreases slightly after 2000 cycles of tensile, which is believed to be a delayed response brought about by electron beam irradiation. The experiment results indicate that the proposed MEMS device will facilitate the in-situ test of 1D/2D nanomaterials.

Crmnv and Crmntiv Heas Elastic Properties for Use in Beam Exit Windows for MW Irradiation Facilities

The choice of a material and the engineering design that is intended to lead to a beam exit window capable of sustaining mechanical and thermal loads in a high-radiation environment, while minimizing the beam loss and maximizing the window lifetime is discussed. Thin titanium windows have been typically used in industrial accelerators in the tens of kW beam power [1].The focus of this research is to conduct fundamental studies related to the choice of a material, from a material science point of view, for MW-class beam exit windows and an engineering design, including parameters such as the window size, thickness, and cooling scheme, suitable for industrial accelerators. CrMnV and CrMnTiV HEAs were selected for this study. According to Yang et al., [2], 1.1 and 6.6% should be expected as the criteria for forming high entropy stabilized solid solution phases. The two parameters of the CrMnV and CrMnTiV alloys are and respectively. Therefore, the two alloys are expected to be solid solution.The mechanical properties of CrMnV and CrMnTiV solid solution HEAs exit window prior to E-beam irradiation were measured using nanoindentation. The nanoindentation testing was carried out using XP Nanoindenter tester equipped with a three-sided diamond Berkovich indenter tip with maximum displacement of 2000 nm. The hardness is measured as 5.2 and 6.1 GPa for the bulk CrMnV and CrMnTiV solid solution HEAs at a depth of indentation of 900 nm respectively, Fig. 1. We also observe that both solid solution CrMnV and CrMnTiV HEAs depict indentation size effect. References Chmielewski A.G., Zimek, Z., Panta P., Drabik W., Radiat. Phys. Chem. 45 1029 (1995). Yang, X. and Y. Zhang, Prediction of high-entropy stabilized solid-solution in multi-component alloys. Materials Chemistry and Physics, 2012. 132(2-3): p. 233-238. Figure 1

Electron beam irradiation-triggered strontium delivery from a bioresorbable fracture fixation device

A fracture fixation device capable of stimulating bone formation and inhibiting bone resorption is desirable for treating osteoporotic fractures. Strontium (Sr) is known to have a dual effect on bone metabolism, but its use in fracture fixation devices is still limited to date as the regulation of Sr release remains difficult. In this work, a bioresorbable device with controlled Sr release capability is fabricated by incorporating strontium carbonate (SrCO3) into a poly (lactic-co-glycolic acid) (PLGA) filament followed by surface modification using electron beam (ebeam) near-surface irradiation. The presence of SrCO3 effectively retards autocatalytic polymer degradation and improves the mechanical durability of the device. The utilization of ebeam irradiation induces controlled surface degradation of the polymer matrix and triggers the release of Sr in a predictable manner. In vitro experiment results reveal that the ebeam irradiated PLGA-SrCO3 filaments have good biocompatibility and can promote the proliferation of human foetal osteoblasts (hFOBs), making it potentially useful for improving osteoporotic fracture fixation.

Effect of Various Doses of Electron Beam Irradiation Treatment on the Quality Characteristics of Vacuum-Packed Dry Fermented Sausage during Refrigerated Storage.

In this study, we investigated the effect of electron beam irradiation on the physicochemical, microbiological, and sensory attributes of dry fermented sausage during 8 weeks of refrigerated storage at 4°C. The five doses of e-beam irradiation applied were: 0 kGy (control) and 1, 2, 3, and 4 kGy. All the experimental treatments led to a significant decrease in pH values during the storage period of 60 days (P<0.05). The 2-kGy treatment caused a significant (P<0.05) decrease in pH value, bacterial growth (total plate count, Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli), and thiobarbituric acid-reactive substances values than other irradiated fermented sausage batches during the study. Irradiation did not affect the water activity value of the fermented sausage samples. For color characteristics, 3 kGy exhibited significantly lower (P<0.05) L* (lightness) values than other irradiation treatments. A similar trend of significantly lower (P<0.05) a* (redness) and b* (yellowness) values was observed in all irradiated treatments than in the control. All the treatments showed no significant differences (P>0.05) in scores in sensory attributes (color and sourness); however, fermented sausage irradiated with 3 kGy had the highest sensory characteristics (overall acceptability) at the end of the storage period. In conclusion, 1, 2, and 3 kGy irradiation treatments can be beneficial for inhibiting lipid oxidation, controlling microbial growth, and maintaining sensory attributes of fermented sausage during storage, thereby enhancing their food safety and shelf stability.

Inactivation of two SARS-CoV-2 virus surrogates by electron beam irradiation on large yellow croaker slices and their packaging surfaces

The detection of infectious SARS-CoV-2 in food and food packaging associated with the cold chain has raised concerns about the possible transmission pathway of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in foods transported through cold-chain logistics and the need for novel decontamination strategies. In this study, the effect of electron beam (E-beam) irradiation on the inactivation of two SARS-CoV-2surrogate, viruses porcine epidemic diarrhea virus (PEDV) and porcine transmissible gastroenteritis virus (TGEV), in culture medium and food substrate, and on food substrate were investigated. The causes of virus inactivation were also investigated by transmission electron microscopy (TEM) and Quantitative Real-time PCR (QRT-PCR). Samples packed inside and outside, including virus-inoculated large yellow croaker and virus suspensions, were irradiated with E-beam irradiation (2, 4, 6, 8, 10 kGy) under refrigerated (0 °C)and frozen (−18 °C) conditions. The titers of both viruses in suspension and fish decreased significantly (P < 0.05) with increasing doses of E-beam irradiation. The maximum D10 value of both viruses in suspension and fish was 1.24 kGy. E-beam irradiation at doses below 10 kGy was found to destroy the spike proteins of both SARS-CoV-2 surrogate viruses by transmission electron microscopy (TEM) and negative staining of thin-sectioned specimens, rendering them uninfectious. E-beam irradiation at doses greater than 10 kGy was also found to degrade viral genomic RNA by qRT-PCR. There were no significant differences in color, pH, TVB-N, TBARS, and sensory properties of irradiated fish samples at doses below 10 kGy. These findings suggested that E-beam irradiation has the potential to be developed as an efficient non-thermal treatment to reduce SARS-CoV-2 contamination in foods transported through cold chain foods to reduce the risk of SARS-CoV-2 infection in humans through the cold chain.

A new pre-gelatinized starch preparing by spray drying and electron beam irradiation of oat starch

As a green and safe physical technology, irradiation is increasingly used to improve starch properties. In the study, oat starch was pre-gelatinized at 70 °C followed by spray drying. Subsequently, the spray-dried starch (SDS) was exposed to electron beam (e-beam) irradiation at different doses to obtain new pre-gelatinized starch. Spray drying caused a decrement in the ratio of long B3 chains and the molecular weight of starch. Spray-dried starch (SDS) slightly increased solubility and swelling power than native starch. When SDS was subjected to e-beam irradiation, its solubility and swelling power increased dramatically, but the pasting viscosities, gelatinization temperatures, apparent viscosity, storage modulus (G′) and lost modulus (G″) reduced. The depolymerization of starch molecules and the breakage of amylopectin chains might be responsible for changing the physicochemical properties of e-beam irradiated starch. These results showed that spray drying combined with e-beam irradiation would potentially produce new pre-gelatinized starch.

Atomically Sharp, Closed Bilayer Phosphorene Edges by Self-Passivation.

Two-dimensional crystals' edge structures not only influence their overall properties but also dictate their formation due to edge-mediated synthesis and etching processes. Edges must be carefully examined because they often display complex, unexpected features at the atomic scale, such as reconstruction, functionalization, and uncontrolled contamination. Here, we examine atomic-scale edge structures and uncover reconstruction behavior in bilayer phosphorene. We use in situ transmission electron microscopy (TEM) of phosphorene/graphene specimens at elevated temperatures to minimize surface contamination and reduce e-beam damage, allowing us to observe intrinsic edge configurations. The bilayer zigzag (ZZ) edge was found to be the most stable edge configuration under e-beam irradiation. Through first-principles calculations and TEM image analysis under various tilting and defocus conditions, we find that bilayer ZZ edges undergo edge reconstruction and so acquire closed, self-passivated edge configurations. The extremely low formation energy of the closed bilayer ZZ edge and its high stability against e-beam irradiation are confirmed by first-principles calculations. Moreover, we fabricate bilayer phosphorene nanoribbons with atomically sharp closed ZZ edges. The identified bilayer ZZ edges will aid in the fundamental understanding of the synthesis, degradation, reconstruction, and applications of phosphorene and related structures.

Athermal glass work at the nanoscale: Engineered electron-beam-induced viscoplasticity for mechanical shaping of brittle amorphous silica

Amorphous silica deforms viscoplastically at elevated temperatures, which is common for brittle glasses. The key mechanism of viscoplastic deformation involves interatomic bond switching, which is thermally activated. Here, we precisely control the mechanical shaping of brittle amorphous silica at the nanoscale via engineered electron–matter interactions without heating. We observe a ductile plastic deformation of amorphous silica under a focused scanning electron beam with low acceleration voltages (few to tens of kilovolts) during in-situ compression studies, with unique dependence on the acceleration voltage and beam current. By simulating the electron–matter interaction, we show that the deformation of amorphous silica depends strongly on the volume where inelastic scattering occurs. The electron–matter interaction via e-beam irradiation alters the Si–O interatomic bonds, enabling the high-temperature deformation behavior of amorphous silica to occur athermally. Finally, by systematically controlling the electron–matter interaction volume, it is possible to mechanically shape the brittle amorphous silica on a small scale at room temperature to a level comparable to glass shaping at high temperatures. The findings can be extended to develop new fabrication processes for nano- and microscale brittle glasses.

Design and commissioning of an e-beam irradiation beamline at the Upgraded Injector Test Facility at Jefferson Lab

The Upgraded Injector Test Facility (UITF) at Jefferson Lab is a continuous-wave superconducting linear accelerator capable of providing an electron beam with energy up to 10 MeV. A beamline for electron-beam irradiation has been designed, installed and successfully commissioned at this facility, aimed at the degradation study of 1,4-dioxane and per- and polyfluoroalkyl substances (PFAS) in wastewater treatment. A solenoid with a peak axial magnetic field of up to 0.28 T and a set of raster coils were used to obtain a Gaussian beam profile with a transverse standard deviation of ∼15.0mm at the target location. Monte-Carlo simulations using FLUKA were carried out to calculate the total absorbed dose and the dose distribution in the sample volume inside the target cell. The simulations were benchmarked experimentally by dosimetry mapping using opti-chromic dosimeters. The results of the irradiation experiments showed a ∼95% reduction of 1,4-dioxane in ultra-pure water for a dose of 1 kGy, demonstrating the potential of electron-beam irradiation towards addressing growing challenges in environmental remediation.

Synthesis and Assessment of AMPS-Based Copolymers Prepared via Electron-Beam Irradiation for Ionic Conductive Hydrogels.

In this study, ionic conductive hydrogels were prepared with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). Acrylic acid (AA), acrylamide (AAm), and 2-hydroxyethyl acrylate (HEA) were used as comonomers to complement the adhesion properties and ion conductivity of AMPS hydrogels. Hydrogels were prepared by irradiating a 20 kGy dose of E-beam to the aqueous monomer solution. With the E-beam irradiation, the polymer chain growth and network formation simultaneously proceeded to form a three-dimensional network. The preferred reaction was determined by the type of comonomer, and the structure of the hydrogel was changed accordingly. When AA or AAm was used as a comonomer, polymer growth and crosslinking proceeded together, so a hydrogel with increased peel strength and tensile strength could be prepared. In particular, in the case of AA, it was possible to prepare a hydrogel with improved adhesion without sacrificing ionic conductivity. When the molar ratio of AA to AMPS was 3.18, the 90° peel strength of AMPS hydrogel increased from 171 to 428 gf/25 mm, and ionic conductivity slightly decreased, from 0.93 to 0.84 S/m. By copolymerisation with HEA, polymer growth was preferred compared with chain crosslinking, and a hydrogel with lower peel strength, swelling ratio, and ionic conductivity than the pristine AMPS hydrogel was obtained.

Synergistic effect of e-beam irradiation and graphene oxide incorporation on thermal, mechanical, and barrier properties of poly (ethylene-co-vinyl alcohol) film

Graphene and its derivatives, such as graphene oxide (GO), have attracted enormous interest from academia and industry because of its unique electrical, mechanical, and thermal properties, which can lead to enhanced material performance. In the present study, low contents of GO were incorporated into the poly (vinyl alcohol-co-ethylene) (EVOH). First, the GO was prepared by chemical oxidation of graphite employing a modified Hummer's method. The GO content of 0.1–0.3 wt % was incorporated in the EVOH matrix using a twin-screw extruder and extrusion blown film process to prepare flexible films. EVOH/GO film samples were irradiated at 100 kGy, using a 1.5 MeV electron-beam accelerator, at room temperature, in the presence of air. GO was characterized by XRD, ATR-FTIR, FE-SEM, and TEM analysis. XRD patterns of GO show a sharp reflection peak at 2θ = 10° (d001) corresponding to a d-spacing at 8.84 Å, characteristic of GO. The non-irradiated and irradiated samples were characterized by XRD, FEG-SEM, TG, DSC, oxygen transmission rate (OTR), UV/VIS analysis, and tensile tests. EVOH/GO nanocomposite films had an improved oxygen barrier, while also retaining fairly good transparency. As an effect of e-beam irradiation, the thermal, mechanical, and barrier behaviors of the nanocomposite films were even better than non-irradiated film samples, and obviously better than neat EVOH. Thus, the incorporation of low contents of GO followed by e-beam radiation treatment might be an interesting alternative to produce packaging materials based on EVOH with outstanding performance even under very humid conditions.