Irradiation System Research Articles

Irradiation damage evolution dependence on misorientaton angle for ∑ 5 grain boundary of Nb: An atomistic simulation-based study

Abstract Niobium as refractory element holds ability to arrest the primary radiation damage in reactor's fissionable conditions and can withstand high temperature applications. We have inclined the investigation of irradiated Nb ∑ 5 symmetric tilt angled-grain boundary (STGB) models at two high-angled grain boundary misorientation: 53.13 ° (∑ 5(2-10)/ (120)) and 36.87 ° (∑ 5(3-10)/ (130)) respectively. A hybrid of Ziegler-Biersack-Littmark (ZBL) and embedded atom method (EAM) potentials were superimposed to simulate radiation damage. Statistical averaging of the displacement cascades were conducted to study dynamic evolution of the point defects and interstitial clusters at varying magnitudes of primary knock-on atom (PKA) energies, irradiation temperatures and PKA directions respectively. The irradiated GB models were compared with a irradiated bulk Nb specimen and the results of the study indicate that the irradiated Nb system with greater misorientation angle i.e., Nb ∑ 5 (θ = 53.13 ° ) survived with lower number Frenkel pair defects as well as the population small-sized interstitial clusters. The cluster analysis indicated the highest population of interstitial clusters survived in Nb STGB models were irradiated along <1 3 5> PKA direction and 100 keV recoil energies respectively.

An Innovative Biphasic Reaction System for Highly Selective Benzene Hydroxylation based on Photocatalytic Polymer Composites

AbstractThe hydroxylation of benzene to phenol in presence of hydrogen peroxide was performed using a new biphasic system consisting of a solid phase, a photocatalytically active monolithic polymer composite, immersed in an aqueous phase in which H2O2 is dissolved. In detail, ZnO photocatalytic particles were embedded into the hydrophobic syndiotactic polystyrene (sPS) polymer. Zinc oxide nanostructures (ZnO NSs) were synthesized by an electrochemical procedure. The surface morphology and structure of ZnO nanoparticles and ZnO‐sPS monolithic aerogel composite (ZnO/sPS) were investigated by scanning electron microscopy, X‐ray diffraction and X‐ray photoelectron spectroscopy analysis. Photocatalytic results evidenced that, under UV irradiation, both ZnO NSs and biphasic system water‐photocatalytic composites had a high benzene oxidative property but with very low phenol yield (<2 %) at pH=7. To enhance the phenol selective formation, the pH of the aqueous solution surrounding the photocatalytic polymer composite was modified. A phenol yield of about 94 % and benzene conversion higher than 99 % was obtained in alkaline conditions (pH=11).

Emergence of Optical Activity and Surface Morphology Changes in Racemic Amino Acid Films Under Circularly Polarized Lyman‐α Light Irradiation

ABSTRACTThe homochirality of life remains one of the most enigmatic issues in the study of the origin of life. A proposed mechanism for symmetry breaking involves irradiation by circularly polarized light (CPL). To investigate the photoreaction of amino acids under CPL irradiation, a vacuum ultraviolet (VUV) CPL irradiation system was developed at the synchrotron light source UVSOR‐III. Hydrogen Lyman‐α CPL (121.6 nm) is considered a potential asymmetric source in space. Therefore, racemic alanine film samples were irradiated with Lyman‐α CPL to explore the photoreaction of biomolecules. Circular dichroism (CD) spectra measurements revealed that irradiation with right‐ (left‐) handed CPL induced a positive (negative) anisotropy factor g in the wavelength range of 180–240 nm. However, the spectra differed from those of enantiopure alanine, exhibiting broad wavelength ranges and no sign change. Liquid chromatography‐mass spectrometry (LC–MS) measurements indicate formation of larger molecules, such as oligomeric alanine adducts or modified oligomers after the Lyman‐α CPL irradiation. Additionally, CPL irradiation considerably changes the microstructure of the alanine film surface, leading to the formation of circular network aggregates on the scale of 100 nm. The morphology changes in the alanine film and/or the formation of the larger molecules could be possible causes of the modified anisotropy factor spectra compared to those of enantiopure alanine. These findings highlight the need for further research on the photoreaction of biomolecules in solid states under VUV CPL irradiation, particularly in the photoionization energy range, to validate the cosmic scenario of homochirality.

Feed system tracking receive/transmit shaped Cassegrain antenna C/K bands

Background. The need to create, space communication stations based on mobile carriers, for example, on ships, requires the use of multi-band reflector antennas irradiating systems that ensure the combination of not only channels for receiving and transmitting high-frequency signals, but also direction-finding channels for constructing a monopulse tracking system. Aim. Study of the possibility of creating an irradiation system that ensures the combination of reception and transmission of signals in the multi-band reflector antenna in spaced ranges with frequency bands C(Rx) – 21 %, C(Tx) – 16 % and K(Rx) – 21 %, with the implementation of a monopulse angular automatic tracking system in both receiving ranges. Methods. Development of a three-band irradiation system that ensures the implementation of automatic tracking in both receiving ranges. Analysis of the characteristics of a three-band irradiation system that ensures the implementation of reception and automatic tracking in both receiving ranges. Results. Development of a three-band irradiation system that ensures the implementation of automatic tracking in both receiving ranges. Analysis of the characteristics of a three-band irradiation system that ensures the implementation of reception and automatic tracking in both receiving ranges. Conclusion. The irradiation system of the multi-band reflector antenna for mirrors with profiled surfaces is proposed, with the implementation of combined signal reception in the C(Rx) and K(Rx) frequency ranges with a 21 % band and signal transmission in the C(Tx) frequency range with a 16% band, and the formation of partial RPs in both receiving ranges for the implementation of a monopulse angular tracking system. The following characteristics of the irradiation system are implemented: cross-polarization isolation of more than 30 dB, the formation of identical partial RPs and a stable tracking mode based on signals from onboard repeaters in communication systems with frequency reuse.

Comparison of chamber beam geometry robustness to mispointing, imbalance and target offset for direct-drive laser fusion facilities

Abstract This study focuses on the optimization of beam chamber geometry designs for future direct-drive laser facilities. It provides a review of leading target chamber geometries, with a particular emphasis on random errors. Through comprehensive solid-sphere illuminations and analysis, we identify an optimized beam geometry design, highlighting its robustness and performance under realistic experimental conditions. Three major sources of random errors are evaluated, closely linked to experimental evaluations at OMEGA. The findings underscore the importance of optimizing the irradiation system alongside beam pattern considerations to enhance the efficiency and reliability of inertial confinement fusion experiments. We conclude that for a desired illumination uniformity of 1% in the presence of system errors, the split icosahedron design is the most robust. However, for a 0.3% uniformity goal, the charged-particle, icosahedron, and t-sphere methods exhibit similar performance.

Development of Beam Irradiation System for Life Science Research at RAON

Development of Beam Irradiation System for Life Science Research at RAON

A simulation study of MR-guided proton therapy system using iron-yoked superconducting open MRI: a conceptual study.

Radiotherapy platforms integrated with magnetic resonance imaging (MRI) have been significantly successful and widely used in X-ray therapy over the previous decade. MRI provides greater soft-tissue contrast than conventional X-ray techniques, which enables more precise radiotherapy with on-couch adaptive treatment planning and direct tracking of moving tumors. The integration of MRI into a proton beam irradiation system (PBS) is still in the research stage. However, this could be beneficial as proton therapy is more sensitive to anatomical changes and organ motion. In this simulation study, we considered the integration of PBS into the 0.3-T superconducting open MRI system. Our proposed design involves proton beams traversing a hole at the center of the iron yoke, which allows for a reduced fringe field in the irradiation nozzle while maintaining a large proton scan field of the current PBS. The shape of the bipolar MRI magnets was derived to achieve a large MRI field-of-view. To monitor the beam position and size accurately while maintaining a small beam size, the beam monitor installation was redesigned from the current system. The feasibility of this system was then demonstrated by the treatment plan quality, which showed that the magnetic field did not deteriorate the plan quality from that without the magnetic field for both a rectangular target and a prostate case. Although numerous challenges remain before the proposed simulation model can be implemented in a clinical setting, the presented conceptual design could assist in the initial design for the realization of the MR-guided proton therapy.

Combined electrochemical in-situ activated chlorine production and photocatalytic for degradation of dimethyl phthalate using membrane filtration recycle TiO2

The ultraviolet (UV)/chlorine advanced oxidation process (AOP), involving addition of activated chlorine to the UV irradiation system to generate hydroxyl radicals (HO·) and chlorine radicals (Cl·), is promising in addressing refractory organic matters. Herein, activated chlorine was electrochemically in-situ generated under low concentrations of chloride ions (Cl−), serving as the chlorine source. A UV/electrochemistry/titanium dioxide (UV/E/TiO2) system was established by coupled membrane filtration. TiO2 was separated and circulated to remove dimethyl phthalate (DMP). Impacts of catalyst (TiO2), Cl− concentrations, and initial pH on DMP degradation were investigated under different conditions. The results revealed that compared with E and UV/TiO2 systems, the UV/E/TiO2 system substantially enhanced the DMP degradation (from 5.11 % and 22.54 % to 78.33 %), with a synergistic factor of 1.16. Radical quenching experiments confirmed that HO·and Cl·were the primary reactive substances for DMP degradation in the UV/E/TiO2 system. Fluorescence probe experiments, coupled with HPLC and LC–MS analysis, revealed a continuous decrease in Cl− in the UV/E/TiO2 system due to ongoing photolysis, generating more HO·for DMP degradation in contrast to the E/TiO2 system. In conclusion, the coupled UV/E/TiO2 system can promote the degradation of refractory organic pollutants in water environments, showcasing significant potential.

Dual-Band Irradiation System of Ka/Q Band for Satellite Communication Station

Dual-Band Irradiation System of Ka/Q Band for Satellite Communication Station

Irradiation system for biological experiments on BL14B1 at SPring-8

We present an irradiation system for biological experiments on BL14B1 beam line of SPring-8, where enables to use white and monochromatic X-rays (from 5 to 90 keV). An effective energy of white X-rays is assessed as 120 keV and their average dose rate is determined as approximately 170 Gy/s using a l-alanine dosimeter. Also, we speak about dosimetry of monochromatic X-rays using an optical stimulated luminescence detector. Average dose rates of monochromatic X-rays with 33.0, 33.2, 33.4 and 34.0 keV are estimated as 0.099 ± 0.006 Gy/s. The irradiation dose of white and monochromatic X-rays, of course, can be monitored using ionization chamber. When we use monochromatic X-rays with 33.2 keV, where is the K-shell absorption edge of iodine, Auger electrons are emitted, leading significant improvement of biological effectiveness. Thus, we have estimated the absorbed dose low-energy secondaries, such as Auger electrons and characteristic X-rays, emitted from iodine as 1.3 × 10−2 Gy/mM/min at BL14B1, depending on iodine concentration.

Modelling of radiation and flow fields in in-duct ultraviolet germicidal irradiation systems with and without ribs

In-duct ultraviolet germicidal irradiation systems (ID-UVs) is a promising technology for the development of biosecure buildings. This study explored the Computational Fluid Dynamics (CFD) method for accurately predicting the inactivation efficiency of ID-UVs. The results showed that the setting of ‘Divisions’ is crucial to the accuracy of radiation field modelling, and 15 × 15 was considered to be a reasonable value in this study. In addition, residence time and deposition ratio are two crucial parameters determining the average UV dose (AD) received by microbial particles, thereby influencing the inactivation efficiency. For ID-UVs without ribs, the Renormalization Group (RNG) [Formula: see text] model largely overestimated these two parameters, while the Reynolds Stress Model (RSM) with correcting fluctuation velocity improved the predictive accuracy of AD by 10.0%. For ID-UVs with ribs, the RNG [Formula: see text] model overestimated the eddy size and AD by 28.6% and 12.0%, respectively. The RSM model provided results closer to the Large Eddy Simulation. Adding 0.10 H (H: duct height) ribs increased the inactivation efficiency for MS2 Bacteriophage by 19.0%–64.3%, with an additional pressure drop of only 3.3 Pa. These findings contributed to a reliable CFD framework and provided novel ideas for improving inactivation efficiency.

Applications of robot-assisted UV disinfection in dentistry.

Maintaining a microbial-free environment in healthcare facilities is more widely recognized as an essential component of therapies to minimize transmission of viruses associated with healthcare sector. The global spread of COVID-19 and recent outbreaks have presented humanity with previously unheard-of challenges. The development of autonomous disinfection robots seems to be necessary given the urgent need for constant sterilization in the face of a labor shortage. Due to their automated and perceived cost advantages by eliminating cleaning staff, these robots are being advertised more and more as an easy solution to immediately disinfect rooms and operating areas. The use of these services lowers the danger of infection, and expense of traditional cleaning and, most significantly, builds trust and security in medical facilities. Currently, routine (manual) cleaning is not replaced by disinfection robots; rather, they may support it. Additional hospital and device design alterations are necessary to address the overshadowing (visibility) issue allowing Ultraviolet disinfectant (UV-D) robots move freely in the medical environment. More technical developments and clinical studies in a variety of hospitals are needed to overcome the current challenges and find ways to integrate this unique technology into hospitals now and in the future. Thus, we present a review that includes detailing all elements required for it to function, as well as both its advantages and disadvantages. To the best of our knowledge, very limited studies have collected an in- depth data on the sterilization effect using a disinfection robot in the field of dentistry. We believe that this data will work as a foundation in more advanced uses at diverse sites that require disinfection and will highlight unsolved challenges and potential research avenues for UV robot operational concerns in dental hospitals. The goal of this work is to offer a comprehensive manual for UV-D robots covering pertinent information on traditional Ultraviolet germicidal irradiation (UVGI) system along with advancements in UV-D robots and thereby focusing on in-depth application in medical and dental facilities.

Microprocessor Control of the Electric Drive of Variable Radiation Installation and Ensuring of Operation Reliability

Introduction. The introduction of energy-saving technologies has become particularly relevant in recent years, when energy prices have been constantly increasing. This is particularly important for greenhouse farms, where the main condition for growing plants indoors is the creation of artificial climatic conditions: temperature, humidity, and lighting.Problem Statement. Given the light and the dark stages of photosynthesis, it becomes possible to use a variable light field in the plant-growing photoculture, which is created by light installations with variable radiation. The development of an energy-saving electric drive and automated control systems for the parameters of artificial climatic conditions when growing plants indoors results in reducing energy consumption and increasing the reliability of the technological process in greenhouses of agro-industrial complex.Purpose. Implementation of energy-saving variable illumination irradiating systems with an automated control system for greenhouse farms.Materials and Methods. A lighting installation with rotation of the irradiator in the vertical and horizontal planes with a discrete electric drive and microprocessor control has been used.Results. The current state of variable irradiating systems with energy-saving radiation sources has been analyzed. The use of a discrete electric drive with an automated control system has been proposed. The installation with a DNAT-400 radiation source and a ZHO-01 reflector enables irradiating an area of up to 100 m2. The maximum exposure to photosynthetically active radiation is 30 W/m2, and the irradiation irregularity does not exceed 20%. At the same time, electricity savings reach about 10 thousand kWh per season. The yield and quality of products remain unchanged.Conclusions. The results of the research have confirmed the feasibility of practical implementation of variable irradiation system for energy efficiency of greenhouse operations.

Accumulated melanin in molds provides wavelength-dependent UV tolerance.

Fungal contamination poses a serious threat to public health and food safety because molds can grow under stressful conditions through melanin accumulation. Although ultraviolet (UV) irradiation is popular for inhibiting microorganisms, its effectiveness is limited by our insufficient knowledge about UV tolerance in melanin-accumulating molds. In this study, we first confirmed the protective effect of melanin by evaluating the UV sensitivity of young and mature spores. Additionally, we compared UV sensitivity between spores with accumulated melanin and spores prepared with melanin biosynthesis inhibitors. We found that mature spores were less UV-sensitive than young spores, and that reduced melanin accumulation by inhibitors led to reduced UV sensitivity. These results suggest that melanin protects cells against UV irradiation. To determine the most effective wavelength for inhibition, we evaluated the wavelength dependence of UV tolerance in a yeast (Rhodotorula mucilaginosa) and in molds (Aspergillus fumigatus, Cladosporium halotolerans, Cladosporium sphaerospermum, Aspergillus brasiliensis, Penicillium roqueforti, and Botrytis cinerea). We assessed UV tolerance using a UV-light emitting diode (LED) irradiation system with 13 wavelength-ranked LEDs between 250 and 365nm, a krypton chlorine (KrCl) excimer lamp device, and a low pressure (LP) Hg lamp device. The inhibition of fungi peaked at around 270nm, and most molds showed reduced UV sensitivity at shorter wavelengths as they accumulated pigment. Absorption spectra of the pigments showed greater absorption at shorter wavelengths, suggesting greater UV protection at these wavelengths. These results will assist in the development of fungal disinfection systems using UV, such as closed systems of air and water purification.

Role of the Controlled Periodic Illumination (CPI) for Enhancing the Photonic Efficiency of a Photocatalytic System

AbstractPhotonic efficiency measurements of the photoeffects at semiconductor surfaces for pollutant abatement and value‐added product generation (e. g. H2 in the hydrogen evolution reaction, HER) are usually carried out under continuous irradiation of the catalyst. In the last decades, Controlled Periodic Illumination (CPI) was proposed as a way to increase the photonic efficiency of irradiated semiconductor systems. CPI consists in the modulation of the incident radiant power, alternating light and dark periods with given duty cycle (γ), intensity (I) and frequency (f). The rationale underlying the use of CPI to enhance photonic efficiency is the exploitation of dark periods to allow slow reactions proceed, to induce new reactions or to free up space on the surface of the catalyst. In this short review, we will highlight the strengths and weaknesses of some of the works published so far on the abatement of pollutants and the production of hydrogen using CPI.

Photo-induced non-collinear interlayer RKKY coupling in bulk Rashba semiconductors

The interplay between light-matter, spin-orbit, and magnetic interactions allows the investigation of light-induced magnetic phenomena that are otherwise absent without irradiation. We present our analysis of light-driven effects on the interlayer exchange coupling mediated by a bulk Rashba semiconductor in a magnetic multilayer. The collinear magnetic exchange coupling mediated by the photon-dressed spin-orbit coupled electrons of BiTeI develops light-induced oscillation periods and displays new decay power laws, both of which are enhanced with an increasing light-matter coupling. For magnetic layers with non-collinear magnetization, we find a non-collinear magnetic exchange coupling uniquely generated by light-driving of the multilayer. As the non-collinear magnetic exchange coupling mediated by the photon-dressed electrons of BiTeI is unique to the irradiated system and it is enhanced with increasing light-matter coupling, this effect offers a promising platform of investigation of light-driven effects on magnetic phenomena in spin-orbit coupled systems. In this platform, light properties, such as its intensity, can serve as external knobs for inducing non-collinear couplings of the interlayer exchange and for modulating the collinear couplings. Both of these effects signify the photo-generated modification in the spin textures of spin-orbit coupled electrons in BiTeI.

Air disinfection performance of upper-room ultraviolet germicidal irradiation (UR-UVGI) system in a multi-compartment dental clinic

Multi-compartment dental clinics present significant airborne cross-infection risks. Upper-room ultraviolet germicidal irradiation (UR-UVGI) system have shown promise in preventing airborne pathogens, but its available application data are insufficient in multi-compartment dental clinics. Therefore, the UR-UVGI system's performance in a multi-compartment dental clinic was comprehensively evaluated in this study. The accuracy of the turbulence and drift flux models was verified by experimental data from ultrasonic scaling. The effects of the ventilation rate, irradiation zone volume, and irradiation flux on UR-UVGI performance were analyzed using computational fluid dynamics coupled with a UV inactivation model. Different patient numbers were considered. The results showed that UR-UVGI significantly reduced virus concentrations and outperformed increased ventilation rates alone. At a ventilation rate of six air changes per hour (ACH), UR-UVGI with an irradiation zone volume of 20% and irradiation flux of 5 μW/cm2 achieved a 70.44% average virus reduction in the whole room (WR), outperforming the impact of doubling the ventilation rate from 6 to 12 ACH without UR-UVGI. The highest disinfection efficiency of UR-UVGI decreased for WRs with more patients. The compartment treating patients exhibited significantly lower disinfection efficiency than others. Moreover, optimal UR-UVGI performance occurs at lower ventilation rates, achieving over 80% virus disinfection in WR. Additionally, exceeding an irradiation zone volume of 20% or an irradiation flux of 5 μW/cm2 notably reduces the improvement rates of UR-UVGI performance. These findings provide a scientific reference for strategically applying UR-UVGI in multi-compartment dental clinics.

Efficient photocatalytic degradation of 24 imidazolium ionic liquids in an N-ZnO/simulated sunlight irradiation system and its mechanism

An efficient nitrogen (N)-ZnO photocatalytic composite was synthesized and well characterized to demonstrate its superior photocatalytic performance as well as the degradation kinetics of 24 ILs in an N-ZnO/Xe lamp irradiation system, as well as the pathways and mechanisms of the photocatalytic degradation (PCD) of typical ionic liquids [OMIm]Br was systematically studied. To investigate the catalytic effect, nitrogen was synthesized from various inorganic and organic nitrogen compounds to ZnO. The NH4NO3-ZnO composite calcined at 300 °C with a molar ratio of NH4NO3 to Zn(NO3)2·6H2O of 10:1 exhibited superior catalytic performance as assessed by SEM, TEM, FT-IR, UVDRS, BET surface area, XPS, and XRD characterizations. After 24 h of exposure to Xe lamp irradiation, all 24 ILs were significantly degraded by the introduction of 0.125 g/L of catalyst, whereas simulated sunlight alone resulted in minimal degradation. The pseudo-first-order rate coefficients (k) for PCD were closely related to the carbon chain length of the alkyl substituents and the type of anion. Multiple linear regression analysis indicated no linear correlation between the parameters E, H°, Eth, and Cv° from the Gaussian calculation and k. Conversely, a positive correlation was observed for EHOMO (B=0.742, β = 1.282, P = 0.011), qH+ (B=1.040, β = 3.284, P = 0.006), and G° (B=0.001, β = 5.400, P = 0.007) with k. Mass spectrometry analysis revealed that the primary PCD pathway for [OMIm]Br involved C-N and/or C-C bond breaking, mono-, di-, and tri-hydroxylation, single and double oxygen transfer, and bromo-substitution reactions.

Prognostic triad: a novel method for decision-making for adjuvant treatment in stage I–II oral squamous cell carcinoma

This study proposes a scoring system for adjuvant irradiation for stage I/II oral squamous cell carcinoma (OSCC). Derivation cohort (119 patients, operated between 2011 and 2014) and a validation cohort (204 patients, operated between 2016 and 2019) were included. In derivation cohort, on univariate analysis, tumor size >2 cm [3-year Disease Free Survival (DFS) 72.5% vs 95.6%, P = 0.039], lymphovascular invasion (58.3% vs 83.6%, P = 0.024), perineural invasion (75% vs 85.6%, P = 0.013), and depth of invasion ≥0.5 cm (73.8% vs 97.5%, P = 0.017) predicted 3-year DFS. Tongue lesions and poor differentiation were added as poor prognosticators based on previously published reports. Patients were grouped as low risk (<3 risk factors) and high risk (≥3 risk factors), with only high-risk group receiving adjuvant irradiation in validation cohort. Overall, 47/119 (39.5%) patients in the derivation cohort and 50/204 (24.5%) patients in validation cohort received adjuvant irradiation. In derivation cohort, 3-year DFS was 93% and 72.5% in the low and high-risk group, respectively. 3-year DFS was 90.7% and 85.8% in the low and high-risk group, respectively for validation cohort. The proposed scoring system reduced the use of adjuvant irradiation by 38%, with similar DFS.

Simultaneous comparison of two independent dosimetry verification systems for VMAT irradiation in assessing 4D dose distribution

Simultaneous comparison of two independent dosimetry verification systems for VMAT irradiation in assessing 4D dose distribution