Ion Beam Irradiation Research Articles

Influence of nitrogen ion on radiation shielding properties of Lead Doped Cadmium Ferrite Nanoparticles

The effect of 5 keV, 200 μm/cm2 nitrogen ion irradiation on the structural, surface morphology, and shielding of lead doped cadmium ferrite nanocomposites are studied using XRD, SEM, TEM and EDX technics. The crystal size decreases after ion irradiation and EDX was used to obtain details of the doped nitrogen atom in the sample. The shielding characteristics of irradiated and unirradiated spinel ferrite samples are investigated for gamma ray radiation shielding using 60Co and 137Cs sources and an HPGe detector. Linear attenuation (μ, cm−1) Mass attenuation coefficients (μ/ρ, cm2/g), and half-value layer (HVL, cm) were determined at different photon energies, and have been measured experimentally and modelled using the MicroShield program. Good agreement was obtained between experimental and modeling results for the irradiated samples. Neutron macroscopic cross section was also calculated for the prepared samples before and after nitrogen ion irradiation. Results showed that the mass attenuation coefficient and other shielding parameters depend upon the nitrogen ion beam irradiation, and highly increased shielding properties nearly twice it's value of unirradiated samples against gamma rays as well as fast neutrons.

Responses of hematopoietic cells after ionizing-irradiation in anemic adult medaka (Oryzias latipes)

Purpose Hematopoietic tissues of vertebrates are highly radiation sensitive and the effects of ionizing radiation on the hematopoiesis have been studied in mammals and teleosts for decades. In this study, radiation responses in the kidney, the main hematopoietic organ in teleosts, were investigated in Japanese medaka (Oryzias latipes), which has been a model animal and a large body of knowledge has been accumulated in radiation biology. Methods Kidney, the main hematopoietic tissue of adult medaka fish, was locally irradiated using proton and carbon ion beams irradiation system of Takasaki Ion Accelerator for Advanced Radiation Application (TIARA), QST, and the effects on peripheral blood cells and histology of the kidney were investigated. Results When only kidneys were locally irradiated with proton or carbon ion beam (15 Gy), the hematopoietic cells in the irradiated kidney and cell density in the peripheral blood decreased 7 days after the irradiation in the same manner as after the whole-body irradiation with γ-rays (15 Gy). These results demonstrate that direct irradiation of the hematopoietic cells in the kidney induced cell death and/or cell cycle arrest and stopped the supply of erythroid cells. Then, the cell density in the peripheral blood recovered to the control level within 4 days and 7 days after the γ-ray and proton beam irradiation (15 Gy), respectively, while the cell density in the peripheral blood did not recover after the carbon ion beam irradiation (15 Gy). The hematopoietic cells in the irradiated kidneys temporarily decreased and recovered to the control level within 21 days after the γ-ray or proton beam irradiation (15 Gy), while it did not recover after the carbon ion beam irradiation (15 Gy). In contrast, the recovery of the cell density in the peripheral blood delayed when anemic medaka were irradiated 1 day after the administration of phenylhydrazine. With and without γ-ray irradiation, a large number of hematopoietic cells was still proliferating in the kidney 7 days after the anemia induction. Conclusions The results obtained strongly suggest that the hematopoietic stem cells in medaka kidney prioritize to proliferate and increase peripheral blood cells to eliminate anemia, even when they are damaged by high-dose irradiation.

Anisotropic deformation of colloidal particles under 4 MeV Cu ions irradiation

Anisotropic deformation of colloidal particles was investigated under ion irradiation with 4 MeV Cu ions. In this study, 0.5 μm-diameter colloidal silica particles, 0.5 μm-diameter Au-silica core–shell particles, and 15 nm-diameter Au colloids embedding in a planar Si/SiO2 matrix were irradiated with 4 MeV Cu ions at room temperature and normal incidence. In colloidal silica particles, ion beam irradiation causes dramatic anisotropic deformation; silica expands perpendicular to the beam and contracts parallel, whereas Au cores elongate. Au colloids in a planar SiO2 matrix were anisotropically transformed from spherical colloids to elongated nanorods by irradiating them with 4 MeV Cu ions. The degree of anisotropy varied with ion flux. Upon irradiating the embedded Au colloids, dark-field light scattering experiments revealed a distinct color shift to yellow, which indicates a shift in surface plasmon resonance. A surface plasmon resonance measurement reveals the plasmon resonance bands are split along the arrays of Au colloids. Our measurements have revealed resonance shifts that extend into the near-infrared spectrum by as much as 50 nm.

The Damage Analysis for Irradiation Tolerant Spin-Driven Thermoelectric Device Based on Single-Crystalline Y₃Fe₅O₁₂/Pt Heterostructures

Spin-driven thermoelectric (STE) generation based on the combination of the spin Seebeck effect (SSE) and inverse spin Hall effect is an alternative to conventional semiconductor-based thermocouples as it is large scale, low cost, and environment-friendly. The STE device is thought to be radiation hard, making it attractive for space and nuclear technology applications. By using magnetometry, transmission electron microscopy, and the hard X-ray photoemission spectroscopy (HAXPES) measurements, we show that an STE device made of single-crystalline Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> (YIG)/Pt heterostructures has tolerance to irradiation of high-energy heavy ion beams. We used 200 MeV gold ion beams modeling cumulative damages due to fission products emitted from the surface of spent nuclear fuels. By varying the dose level, we confirmed that the thermoelectric and magnetic properties of the single-crystalline YIG/Pt STE device are finite at the ion-irradiation dose up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> ions/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> fluence. In addition, the HAXPES measurements were performed to understand the effects at the interface of YIG/Pt. The HAXPES data suggest that the chemical reaction regarding Fe and O that diminishes the SSE signals is promoted with the increase of the irradiation dose. The understandings of the damage analysis in YIG/Pt are beneficial for developing better STE devices applicable to harsh environmental usages.

Modification of Keggin anion structure with ion beams—A new spectroscopic insights into the effects of keV‐ and MeV‐ion beam irradiation on 12‐tungstophosphoric acid

Ion beam irradiation is a versatile tool for structural modification and engineering of new materials. In this study, 12-tungstophosphoric acid (WPA) films of different thickness were spin-coated on platinized silicon substrate and irradiated with low energy hydrogen ions (10 keV) and swift heavy ions (Bi, Xe, and V) with energies up to 710 MeV. The different energy/fluence combinations allowed controllable structural changes that were investigated in detail using Raman and Infrared spectroscopy. For 120-nm-thick WPA samples, the irradiation led to the decrease of intensity of the skeletal and W-Oc-W bands of Keggin anion in order: Bi < V < Xe (for their applied energy/fluence combination). Also, symmetry change of Keggin anion similar to the one observed in the case of Keggin anions interacting with the supports was observed. For the selected ion beam irradiation parameters, xenon ion beam induced transformation of WPA to polytungstate. For 20-μm-thick WPA samples, the irradiation with hydrogen ion beam induced changes of skeletal vibrations and increased individualistic behavior of Keggin anions. As the fluence increased, the amount of the Keggin anions partially transformed to bronze also increased. Irradiation with vanadium also caused transformation to bronze-like structure but with higher ratio of terminal W=Od bonds. The overall results show clear correlation between degree of structural modification of WPA and the calculated displacement per atom value. These results open possibilities for engineering new catalytically active structures of polyoxometalates with the help of ion beams.

Ion induced effects and defects on surface, structural and mechanical properties of Ni ion irradiated titanium

Abstract Effect of 2 MeV Ni+ ion beam irradiation with varying fluences on the surface, structural, and mechanical characteristics of titanium will be explored. For this objective, titanium targets were exposed to nickel ions obtained from a pelletron linear accelerator with 2 MeV energy and various fluences extending from 3 × 1012 to 7 × 1015 ions/cm2. Penetration features and damage evolution of 2 MeV Ni-ion in titanium have been estimated by employing SRIM-2013 software. Various characterization tools were employed to confirm the modifications in the ion beam irradiated targets. The surface and crystallographic variations of ion beam irradiated targets were explored by employing a scanning electron microscope (SEM) and X-ray diffractometer (XRD). Tensile testing and microhardness analysis was performed by utilizing a software-controlled 50 KN universal tensile testing machine and Vickers’s hardness tester, respectively. The SEM analysis represents random and irregularly distributed sputter morphology for lower ion fluences. With the increase of ion fluence, the pores keep growing radially while the growth rate slows down. At the highest ion fluence, localized melting, evaporation and expulsion of surface material were recorded at the irradiated zone. The X-ray diffraction analysis revealed no additional phases to be developed in the Ni-ion treated titanium. However, a variation in the peak intensity and slight angle/position shifting was reported, which depicts the creation of ion-induced stresses and defects. The mechanical testing results indicated the variations in the mechanical characteristics (yield stress, ultimate tensile stress, hardness etc.) of irradiated titanium. The hardness, yield stress and ultimate tensile strength increased monotonically with the increase of ion fluence. The reported modifications in the mechanical characteristics of irradiated titanium are in good accordance with structural and surface modifications. The stated changes in the irradiated titanium are ascribed to the development of ions induced stress as well to creation, augmentation/expansion, recombination, and annihilation of the ion-induced defects.

Physiological and Differential Proteomic Analysis at Seedling Stage by Induction of Heavy-Ion Beam Radiation in Wheat Seeds.

Novel genetic variations can be obtained by inducing mutations in the plant which help to achieve novel traits. The useful mutant can be obtained through radiation mutation in a short period which can be used as a new material to produce new varieties with high yield and good quality wheat. In this paper, the proteomic analysis of wheat treated with different doses of 12C and 7Li ion beam radiation at the seedling stage was carried out through a Tandem Mass Tag (TMT) tagging quantitative proteomic analysis platform based on high-resolution liquid chromatography-mass spectrometry, and the traditional 60Co-γ-ray radiation treatment for reference. A total of 4,764 up-regulated and 5,542 down-regulated differentially expressed proteins were identified. These proteins were mainly enriched in the KEGG pathway associated with amino acid metabolism, fatty acid metabolism, carbon metabolism, photosynthesis, signal transduction, protein synthesis, and DNA replication. Functional analysis of the differentially expressed proteins showed that the oxidative defense system in the plant defense system was fully involved in the defense response after 12C ion beam and 7Li ion beam radiation treatments. Photosynthesis and photorespiration were inhibited after 12C ion beam and 60Co-γ-ray irradiation treatments, while there was no effect on the plant with 7Li ion beam treatment. In addition, the synthesis of biomolecules such as proteins, as well as multiple signal transduction pathways also respond to radiations. Some selected differentially expressed proteins were verified by Parallel Reaction Monitoring (PRM) and qPCR, and the experimental results were consistent with the quantitative results of TMT. The present study shows that the physiological effect of 12C ion beam radiation treatment is different as compared to the 7Li ion beam, but its similar to the 60Co-γ ray depicting a significant effect on the plant by using the same dose. The results of this study will provide a theoretical basis for the application of 12C and 7Li ion beam radiation in the mutation breeding of wheat and other major crops and promote the development of heavy ion beam radiation mutation breeding technology.

Nano‐Kirigami Structures and Branched Nanowires Fabricated by Focused Ion Beam‐Induced Milling, Bending, and Deposition

Abstract3D nanostructures hold the key to building custom devices with special and flexible functionalities. Ion beam‐induced bending and folding are used for the fabrication of 3D nanostructures from prepared 2D nano‐patterned membranes. Tensile and compressive stresses can be introduced within the layers of a thin membrane under ion beam irradiation to manipulate and control the formation of nano‐kirigamis. Both localized and broader ion beam irradiation can be used to induce bending in the membrane with remarkable control of the bending angle and direction. In this work, an approach to fabricate nano‐kirigamis with focused ion beams (FIBs) is developed. First, helium or neon ion beams are used to mill 2D patterns into the planar membrane with good accuracy, nanoscale, and less damage. Subsequently, gallium ion beam is used to broadly and uniformly irradiate the patterned region to induce out‐of‐plane bending to form nano‐kirigamis. Both upward and downward bending are observed for different thicknesses of membranes. The bending angle is easily controlled by varying the irradiation dosage. Moreover, with FIB‐induced deposition, nanopillars, or nanowires (NWs) can be grown on the membrane before or after bending. Various complex 3D nanostructures and branched NWs can be fabricated using this approach.

Establishment of multi-beam irradiation facility at Wuhan University

A multiple ion beam irradiation facility has been established at Wuhan University to simulate severe irradiation conditions to materials in advanced nuclear energy systems. The platform consists of a 2 × 1.7 MV tandem accelerator, a 200 kV ion implanter, and a 50 kV ion implanter. A single high-energy irradiation chamber and a triple-beam irradiation chamber were set up. China Low Activation Martensitic Steel (CLAM) samples were irradiated with single beam of iron ions and simultaneous dual-beam of iron ions and helium ions at 450 °C. A large number of dislocation loops were observed in the samples after both irradiation conditions. The number density and average size of dislocation loops in the dual-beam irradiated samples were significantly larger than those in the single-beam irradiated samples. Irradiation hardening in dual-beam irradiated samples is more severe than that in single-beam irradiated samples.

Glossary of Terms and Concepts in Medical Padiation Physics - Terminology in Proton and Light Ion Beam Radiation Therapy

Medical radiation physics supports medical diagnostic and treatment process based on the use of ionizing radiation in radiation therapy, nuclear medicine, radiation diagnostics and radiation safety of patients and personnel. However, the successful implementation of this process requires close interaction of specialists in all the above areas. The basis of such interaction is the unification of the terminology and concepts used at various stages of the diagnostic and treatment process. This development is very important for high technological applications such as proton and light ion beam radiation therapy, where the description and correct and unambiguous interpretation of the terminology in the Russianlanguage literature is practically absent. The article presents a glossary on proton and light ion beam radiation therapy which contains the most commonly used terms in this field and explanations for each of them. The glossary is intended for use both in professional education, including postgraduate education, and for medical physicists and radiation oncologists working in radiological medical organizations.

Biological Effectiveness of Ion Beam for In Vitro Cell Irradiations.

Despite numerous ion beam irradiation of cell experiments performed over the past five decades, the relationship between the biological effectiveness of ion beams and the physical characteristics of the ion beam remains unclear. Using 1,118 sets of in vitro cell survival experiments with ion beam irradiation, compiled by the Particle Irradiation Data Ensemble (PIDE) project, the relationship between cell survival and the fluence and linear energy transfer (LET) of the ion beam was established. Unlike previous studies, the closed-form analytical function is independent of photon irradiation and takes a universal form across all ion and cell species. A new understanding of the biological effectiveness of ion beams is crucial for predicting tumor response and toxicities in ion beam radiation therapy, along with radiation protection for high-LET ion beams with low fluence.

Structural analysis of high-energy implanted Ni atoms into Si(100) by X-ray absorption fine structure spectroscopy

Ni silicide synthesis by Ni ion beam irradiation into Si attracts attention due to its advantages including the ability of formation of local structures, the controllability of ion beams, the formability of silicide without heat treatment and the high reproducibility of the resulting specimen. In this work, we investigate the local atomic structure of Si implanted with 3.0 MeV Ni+ ions. Analysis of Ni K-edge fluorescent-yield extended X-ray absorption fine structure reveals that Ni atoms have mixed structure of metallic-like face-centered cubic Ni and NiSi2 phases at the initial stage of the irradiation and the formation of NiSi2 promotes significantly with the ion fluence above 1015 ions⋅cm−2. With consideration of the agreement between the ion fluence threshold for the structural transition and the critical Si-amorphization fluence (7.1 × 1014 ions⋅cm−2), it is concluded that the amorphization of Si plays an important role in the synthesis of the NiSi2 phase in Ni+-irradiated Si.

Effect of Damage Rate on the Cavity Swelling of Pure Nickel Irradiated with Triple Ion Beams

He-H synergistic effects influence the performance of structural materials in fusion reactors. Due to the lack of high-intensity fusion neutron sources, multiple ion beam irradiation has been widely used as an emulation method to study its synergistic effects. However, the damage rate under multiple ion beam irradiation is three to four orders of magnitude higher than that under fusion neutron irradiation, and its effect on the cavity swelling is still unclear. In this study, pure nickel was irradiated with single and triple ion beams to ~1 displacements per atom (dpa) at 450 °C. The damage rate ranged from 1.4 × 10−4 to 1.4 × 10−3 dpa/s, with the identical gas-dose ratios of ~400 H appm/dpa and 100 He appm/dpa. Large and isolated cavities formed under single ion irradiation, while triple ion irradiation induced smaller and denser cavities and higher swelling. As the damage rate increased, the cavity size, density, and swelling decreased, due to the constraint of cavity nucleation and growth processes. The effect of damage rate on cavity evolution under triple ion irradiation strongly depends on two competing factors: the enhancement of aggregation and binding of H/He/vacancies, and the enhancement of vacancies–interstitials recombination with increasing damage rate.

Mechanistic insights into ion-beam induced reduction of graphene oxide: An experimental and theoretical study

Interest in graphene oxide (GO) due to its controllable and adjustable properties has been increasing, especially in the field of electronic and electrochemical charge storage devices. Hence, the modification of surface chemistry and structure of GO can be outlined as crucial for achieving the preferable properties. In this study, we have investigated the influence of 15 keV proton-beam irradiation on GO structure and surface chemistry. The results obtained by Raman spectroscopy, Fourier-transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) were complemented with theoretical ones, obtained by using density functional theory (DFT), semi-empirical (SE) calculations and inelastic thermal spike (iTS) model. The FTIR and XPS results showed that proton irradiation partially reduces the GO with the preferential removal of the alkoxy and epoxy groups. Also, we identified a clear linear relation between the decresase of oxygen content and the decrease of ID/IG ratio i.e. increasing disorder of GO structure. The SE and DFT calculations highlighted a reduction of GO as a single- or multi-step process depending on the type of basal-plane or edge oxygen group. Dynamic SE calculations revealed that for kinetic energy of hydrogen below 1.5 eV the reduction is chemically driven, while at energies higher than 20 eV, the reduction of GO is a result of physical processes. iTS results showed that increase of temperature might contribute to reduction of GO via desorption of epoxy and alcoxy groups, as the least thermally stable groups (T ∼200 °C). The results of this work emphasize the capabilities ion beam irradiation for gradual modification of surface chemistry and structural properties of GO by providing more information about the mechanisms of hydrogen interaction with individual groups, interplay between defect creation, oxygen content and accompaning effects of ion energy loss processes.

Biological effectiveness and relative biological effectiveness of ion beams for in-vitro cell irradiation.

Biological effectiveness and relative biological effectiveness are critical for proton and ion beam radiotherapy. However, the relationship between the two quantities and physical character of ion beams is not well established. By analyzing 1188 sets of in‐vitro cell irradiation experiments using ion beams ranging from protons to 238U, compiled by the Particle Irradiation Data Ensemble (PIDE) project, the biological effectiveness of the ion beams, with cell survival fractionation (SF) as the endpoint, was found to be dependent on the fluence and linear energy transfer (LET) of the ion beam. Consequently, the relative biological effectiveness of the ion beam to photon beam was also established as a function of LET. A common form of relationship among SF, fluence, and LET was found to be valid for all ion beam experiments. The close form relationship could be used for proton and ion beam radiotherapy applications.

Effect of helium and its synergism with displacement damage on microstructure of CLAM steel investigated by single, sequential and simultaneous Fe and He ion irradiations

The reduced-activation ferritic/martensitic steel, China Low-Activation Martensitic (CLAM) steel, was irradiated with single Fe, sequential He/Fe, sequential Fe/He, and simultaneous Fe+He ion beam irradiations at 350 ℃–550 ℃ to a peak displacement damage dose of 15 dpa with 0 - 110 appm/dpa He to explore the effect of He and its synergism with displacement damage on microstructure evolution. The microstructures of all the irradiated specimens were investigated by transmission electron microscope (TEM). For Fe/He sequential irradiation, He inhibited the growth of dislocation loop induced by high-temperature He post-irradiation and reduced the number density of loops. Non-spherical He bubbles were observed only at post-injection He at 550 °C. The size of non-spherical He bubbles produced at 110 appm/dpa was about twice as large as 11 appm/dpa, and the number density increased about 6.4 times. The number density of dislocation loops induced by sequential He/Fe irradiation is the highest, and the average size of loops is comparable to that caused by simultaneous Fe+He irradiation. Moreover, the sequential Fe/He irradiation induced the lowest number density of loops of approximately 64% of the simultaneous Fe+He irradiation. The spherical bubble was observed in all irradiation with He injection above 350 ℃. The average size of spherical He bubbles induced by simultaneous Fe+He irradiation is the largest, and the number density is about 2.6 times that of the sequential Fe/He irradiation. The synergisms of He in different irradiation sequences were analyzed systematically, which helps to better understand the evolutionary processes of the synergistic effect of He and displacement damage.

Swelling as a stabilizing mechanism in irradiated thin films: II. Effect of swelling rate

It has long been observed experimentally that energetic ion-beam irradiation of semiconductor surfaces may lead to spontaneous nanopattern formation. For most ion/target/energy combinations, the patterns appear when the angle of incidence exceeds a critical angle, and the models commonly employed to understand this phenomenon exhibit the same behavioral transition. However, under certain conditions, patterns do not appear for any angle of incidence, suggesting an important mismatch between experiment and theory. Previous work by our group (Swenson and Norris 2018 J. Phys.: Condens. Matter 30 304003) proposed a model incorporating radiation-induced swelling, which is known to occur experimentally, and found that in the analytically-tractable limit of small swelling rates, this effect is stabilizing at all angles of incidence, which may explain the observed suppression of ripples. However, at that time, it was not clear how the proposed model would scale with increased swelling rate. In the present work, we generalize that analysis to the case of arbitrary swelling rates. Using a numerical approach, we find that the stabilization effect persists for arbitrarily large swelling rates, and maintains a stability profile largely similar to that of the small swelling case. Our findings strongly support the inclusion of a swelling mechanism in models of pattern formation under ion beam irradiation, and suggest that the simpler small-swelling limit is an adequate approximation for the full mechanism. They also highlight the need for more—and more detailed—experimental measurements of material stresses during pattern formation.

RDM: An R interface for high-throughput simulation of ion-material interactions using TRIM

The quantitative estimation of the damage caused by ion-material interaction is carried out using Monte Carlo codes as, for instance, TRIM (TRansport of Ions in Matter). Some studies require multiple simulations to be run, varying the ion energy, mass, and charge, or changing the target material. Natural radiation damage in minerals due to the alpha decays in the three natural series is an example. In such applications, the task of calculating the ion damage on the material becomes very time-consuming. The R language code presented in this paper, Radiation Damage in Materials (RDM), is designed to serve as an interface to set parameters, start, collect, and treat the results of multiple TRIM simulations. The main outputs of RDM are the dpa (displacements per atom) and dpa profiles for ion beam irradiation, and, if needed, the natural radiation dpa for any materials to be used in a given study. The fluence of an artificially accelerated ion beam matching the natural radiation dpa is also calculated for studies in which swift heavy ions are used as proxies for natural radiation damage. Program summaryProgram Title: Radiation Damage in MaterialsCPC Library link to program files:https://doi.org/10.17632/jxrt58jprt.1Developer's repository link:https://sites.ifi.unicamp.br/cronologia/rdm/Licensing provisions: GPLv3Programming language: RNature of problem: The calculation of the damage caused in materials by the interaction with ions is a necessary task for planning and interpreting ion beam experiments. Calculations are carried out using the outputs of computer codes, as TRIM, available in the SRIM suit [1], which furnish the quantities of defects generated by the interaction of ions with target materials. Each simulation has to be set up in the TRIM interface or in an input file. If multiple simulations are needed, the time of preparing and running sequential simulations becomes prohibitive. This scenario will appear, for instance, when the effects of the natural radiation are to be calculated, in which case the damage caused by the yields of the alpha decays of the three natural decay series has to be calculated. In this particular application, researchers usually make approximations that are not always satisfactory.Solution method: A R code, Radiation Damage in Materials (RDM), was developed to make possible the high-throughput simulation of the interactions of ions with the matter, using TRI1M as the simulation engine. The code also facilitates the calculation of the natural radiation damage by solving the coupled differential equations for the natural decay chains and automatically queuing the necessary TRIM simulations. RDM is a web browser interface to start simulations and collect and treat simulation outputs. For researchers unfamiliar with TRIM, a stand-alone portable installation of RDM is available.Additional comments including restrictions and unusual features: Multi-threading is not currently included in the code. Therefore simulations run one by one and the Radiation Damage in Materials does not compute commands during simulations. The numerical solution for the radioactive series does not converge for a few specific values of U, Th, and Sm contents. This problem can be circumvented by multiplying the problematic contents by an arbitrary constant and dividing the dpa results by the same constant.

Increased Water-Soluble Yellow Monascus Pigment Productivity via Dual Mutagenesis and Submerged Repeated-Batch Fermentation of Monascus purpureus.

Monascus pigments (MPs) have been used in the food industry for more than 2,000 years and are known for their safety, bold coloring, and physiological activity. MPs are mainly yellow (YMPs), orange (OMPs), and red (RMPs). In this study, a mutant strain Monascus purpureus H14 with high production of water-soluble YMPs (WSYMPs, λmax at 370 nm) was generated instead of primary YMPs (λmax at 420 nm), OMPs (λmax at 470 nm), and RMPs (λmax at 510 nm) produced by the parent strain M. purpureus LQ-6 through dual mutagenesis of atmospheric and room-temperature plasma and heavy ion beam irradiation (HIBI), producing 22.68 U/ml extracellular YMPs and 10.67 U/ml intracellular YMPs. WSYMP production was increased by 289.51% in optimal conditions after response surface methodology was applied in submerged fermentation. Application of combined immobilized fermentation and extractive fermentation improved productivity to 16.89 U/ml/day, 6.70 times greater than with conservative submerged fermentation. The produced WSYMPs exhibited good tone stability to environmental factors, but their pigment values were unstable to pH, light, and high concentrations of Ca2+, Zn2+, Fe2+, Cu2+, and Mg2+. Furtherly, the produced exYMPs were identified as two yellow monascus pigment components (monascusone B and C21H27NO7S) by UHPLC-ESI-MS. This strategy may be extended to industrial production of premium WSYMPs using Monascus.

Study on the surface modification and mechanism of multilayer graphene by ion beam irradiation

To improve the poor dispersion and insufficient interfacial adhesion of reinforced graphene (GN) in copper matrices, the graphene surface is irradiated with a Cu ion beam. To study the mechanism of surface modification of irradiated Cu+2 sample on the surface of graphene, the Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and transmission electron microscope (TEM) are employed. The results of Raman spectroscopy showed that the value of relative intensity ratio I D/I G of the characteristic peaks of unirradiated graphene was 1.2530 where it became 0.8693 after the irradiation process. It showed an 30.6% reduction in the ratio ofI D/I Gindicating that the ion beam irradiation reduces the surface defects of graphene and causes obvious modification effects. XPS results showed that the irradiated Cu deoxidizes with the epoxy, hydroxyl, or carboxyl group on the surface of the GN, resulting in Cu compounds attached to the surface of the GN. In addition, irradiation introduces stress on the graphene surface to promote the formation of a wrinkled structure to cause the surface morphology to change, as witnessed by the rougher surface morphology, as compared to the unirradiated area. The TEM results showed a recrystallization on the surface of the GN after the irradiation process. Moreover, it showed that the GN lattice was significantly qualified. Ion beam irradiation improves the quality of the surface of GN lattice, reduces the surface defects of graphene, and displays obvious modification effects.