Short Radiation Research Articles

Development, Monte Carlo simulations and experimental evaluation of a 3D range-modulator for a complex target in scanned proton therapy

The purpose of this work was to develop and manufacture a 3D range-modulator (3D RM) for a complex target contour for scanned proton therapy. The 3D RM is considered to be a viable technique for the very fast dose application in patient-specific tumors with only one fixed energy. The RM was developed based on a tumor from a patient CT and manufactured with high-quality 3D printing techniques with both polymer resin and aluminum. Monte Carlo simulations were utilized to investigate its modulating properties and the resulting dose distribution. Additionally, the simulation results were validated with measurements at the Marburg Ion-Beam Therapy Centre. For this purpose, a previously developed water phantom was used to conduct fast, automated high-resolution dose measurements. The results show a very good agreement between simulations and measurements and indicate that highly homogeneous dose distributions are possible. The delivered dose is conformed to the distal as well as to the proximal edge of the target. The 3D range-modulator concept combines a high degree of dose homogeneity and conformity, comparable to standard IMPT with very short irradiation times, promising clinically applicable dose distributions for lung and/or FLASH treatment, comparable and competitive to those from conventional irradiation techniques.

UV-C Light-Based Surface Disinfection: Analysis of Its Virucidal Efficacy Using a Bacteriophage Model.

Background: The reprocessing of medical devices has become more complex due to increasing hygiene requirements. Previous studies showed satisfactory bactericidal disinfection effects of UV-C light in rigid and flexible endoscopes. Especially in the context of the current COVID-19 pandemic, virucidal properties are of high importance. In the present study, the virucidal efficacy of UV-C light surface disinfection was analyzed. Methods: MS-2 bacteriophages were applied to the test samples and irradiated by UV-C light using the UV Smart D25 device; unirradiated test samples were used as controls. A dilution series of the samples was mixed with Escherichia coli and assayed. Results: 8.6 × 1012 pfu could be harvested from the unprocessed test samples. In the control group without UV-C exposure, a remaining contamination of 1.2 × 1012 pfu was detected, resulting in a procedural baseline reduction rate with a LOG10 reduction factor of 0.72. The LOG10 reduction factor was found to be 3.0 after 25 s of UV-C light exposure. After 50 and 75 s of UV-C radiation LOG10 reduction factors 4.2 and 5.9, respectively, were found, with all reductions being statistically significantly different to baseline. Conclusions: The tested UV system seems to provide a significant virucidal effect after a relatively short irradiation time.

Selective adsorption of Ba2+ using chemically modified alginate beads with enhanced Ba2+ affinity and its application to 131Cs production

The 131Cs radioisotope with a short half-life time and high average radiation energy can treat the cancer effectively in prostate brachytherapy. The typical 131Cs production processes have a separation step of the cesium from 131Ba to obtain a high specific radioactivity. Herein, we suggested a novel 131Cs separation method based on the Ba2+ adsorption of alginate beads. It is necessary to reduce the affinity of alginate beads to cesium ions for a high production yield. The carboxyl group of the alginate beads was replaced by a sulfonate group to reduce the cesium affinity while reinforcing their affinity to barium ions. The modified beads exhibited superior Ba2+ adsorption performances to native beads. In the fixed-bed column tests, the saturation time and adsorption capacity could be estimated with the Yoon-Nelson model in various injection flow rates and initial concentrations. In terms of the Cs elution, the modified alginate showed better performance (i.e., an elution over 88%) than the native alginate (i.e., an elution below 10%), indicating that the functional group modification was effective in reducing the affinity to cesium ions. Therefore, the separation of cesium from the barium using the modified alginate is expected to be an additional option to produce 131Cs.

Exposure effects of non-ionizing radiation of radio waves on antimicrobial potential of medicinal plants

The high frequency electromagnetic (EM) waves have been proven as potent environmental polluters. The radio towers are considerably increasing to cater to the growing telecommunication requirements. The presented research focuses on the investigation of EM waves on antimicrobial potential of pharmaceutically important medicinal plants viz. Tulsi (Ocimum sanctum L.) and Brahmi (Bacopa monnieri). The similar work has not been reported till date at the best of our knowledge. The medicinal plants were exposed to EM waves of 900 MHz possessing a 1.9 mG magnetic field. Our former investigation on plant physiology gave deteriorative effects on selected plants physiology in terms of growth, chlorophyll content, protein and carbohydrate content. In the presented article, the antimicrobial activity of two plants was inspected through various bacterial and fungal species. In case of B. monnieri, investigations revealed raise in Zone of Inhibition (ZOI) for both the bacterial and fungal strains in the range of 50%, whereas for O. sanctum increase of 63.26% and 59.42% ZOI for bacterial and fungal strains were noted respectively upon 24 h of exposure. Minimum Inhibitory Concentration (MIC) also decreased for 24 and 48 h of exposure. The transient raise in antimicrobial activity indicated the induction of plant defense system which can be considered as positive influence of short term radiation on medicinal properties of plants. Both plants exhibited the highest antimicrobial potential for E. coli and P. chrysogenum showing a prominent decline after 72 h of exposure. A substantial decline in antimicrobial in MIC of B. monnieri reported was 211% against E. coli and 166% against P. chrysogenum upon 144 h of exposure compared to control plants. The antimicrobial potential of O. sanctum was also decreased upon radiation, which is having a 392% reduction against E. coli and a 225% reduction against P. chrysogenum upon 144 h of exposure. The noteworthy deteriorative effects of radio waves on antimicrobial potential have been observed for both the medicinal plants.

Differential Expression of 1-Aminocyclopropane-1-carboxylate Synthase and Oxidase Gene Family in Micro-Tom Tomato Leaves and Roots Under Short Daily UV Radiation

Differential Expression of 1-Aminocyclopropane-1-carboxylate Synthase and Oxidase Gene Family in Micro-Tom Tomato Leaves and Roots Under Short Daily UV Radiation

Short Latency Radiation Induced Osteosarcoma Detected on 18F-FDG PET/CT Scan in Solitary Plasmacytoma.

18Fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) plays a pivotal role in the staging, restaging, and surveillance of various bone tumors, including plasmacytomas and osteosarcomas. Solitary plasmacytomas most frequently occur in the bones and are primarily treated with either surgery or radiotherapy. Radiation-induced osteosarcomas (RIOS) usually develop after a median interval of 11 years between radiation and sarcoma presentation. However, these can rarely present with a short latent period of 4 years or even lesser. In such cases, whole-body imaging plays a vital role in the early detection and management of RIOS. Herein, we present the case of a 29-year-old female patient with solitary plasmacytoma undergoing a follow-up whole-body 18F-FDG PET/CT, which revealed metastatic RIOS after a short latent period.

Effect of surfactant micelle size on the dispersibility of aqueous carbon black particle suspensions prepared by ultrasonication

The effective preparation of particle suspensions is crucial. Herein, we focused on the preparation of carbon black particle aqueous suspensions through ultrasonication to investigate the dispersing mechanisms. Various industrial surfactants were used for the preparation, which resulted in two types of dispersion systems. The first type caused the sizes of the particles in the aqueous solutions to decrease when short ultrasonic irradiation times were employed; however, re-agglomeration occurred after longer times were implemented. The second type employed a long ultrasonication dispersing time and was able to achieve and maintain the smallest-sized particles observed without any re-agglomeration occurring. DLS determined the size of the particles, while PFG-NMR assessed the sizes of the surfactant micelles. Upon comparing these two sizes, we found an obvious relationship between the two regarding their changes during the ultrasonication dispersing process. To better understand these phenomena, the DLVO theory was considered and zeta potential measurements were conducted

High immunoscore as a predictor of outcome in patients who underwent chemoimmuno-therapy in locally advanced rectal cancer: A post-hoc analysis of the correlation between immunoscore and pCR in the Averectal study.

184 Background: The immunoscore (IS), a prognostic score, was first validated in early colon cancer reflecting the immune response against the tumor. It showed potential in its ability to downstage patients with pathologic complete response (pCR) who would potentially benefit from organ-sparing therapies in locally advanced rectal cancer (LARC). We first presented our initial outcome with 37.8% pCR in patients with LARC treated with short course radiation therapy (SCRT) followed by 6 cycles of mFOLFOX plus Avelumab followed by total mesorectal excision (TME) in the ESMO 23rd World Congress on Gastrointestinal Cancer 2021 Conference (presentation # SO-30). Here we are reporting the post-hoc analysis of the correlation between pCR and pre-treatment biopsy IS to further establish the IS as a prognostic score in patients with LARC. Methods: In this Phase II study, 44 patients were accrued from three centers, of whom 40 completed radiotherapy followed by chemoimmunotherapy then TME. 39 patients with available tissue samples, containing tumor cells and its margins, were collected at baseline. CD3 and CD8 cells were counted, and the IS is then derived from the mean density percentiles of CD3 and CD8 positive T cells infiltrating the tumor and in the invasive margin of the tumor. Cutoff for a high IS was established at 62%. We then compared the tumor regression grade (TRG) with the means of IS, using the student t-test. Results: 15 patients with pCR had a mean IS of 68 +/- 22 SD as opposed to a mean IS of 52 +/- 22 SD in 24 patients without pCR (p = 0.036). Conclusions: High IS correlates with TRG as pCR and successfully predicted clinical outcome in LARC patients who underwent chemoimmuno-therapy. It is a promising potential prognostic tool in stratifying patients who would benefit from specific modalities to augment pCR and subsequent organ preservation strategy. Clinical trial information: NCT03503630.

Modified FOLFIRINOX (mFOLFIRINOX) in high risk locally advanced rectal adenocarcinomas.

108 Background: There is limited data with regard to the use of modified 5-fluoroural-leucovorin-irinotecan-oxaliplatin (mFOLFIRINOX) in enabling resection and increasing survival of locally advanced rectal adenocarcinomas (LARC) with high-risk characteristics (T4b status, signet ring histology, etc.) post standard neoadjuvant long course chemoradiation (NACTRT) or short course radiation (SCRT) and chemotherapy. Methods: Patients with LARC from January 2018 to December 2020 receiving mFOLFIRINOX (5-Fluorouracil - 1800mg/m2 over 46 hours, Leucovorin 300mg, Irinotecan 135mg/m2, oxaliplatin 65mg/m2) post NACTRT/SCRT to facilitate curative local resection were evaluated. The primary endpoint was event free survival (EFS), where event was defined as disease progression or recurrence post resection after mFOLFIRINOX. Survivals were calculated using Kaplan-Meier analysis. Results: Forty-seven patients were evaluated with a median age of 33 years (Range:18-59), 45% T4b status, 94% radiological circumferential margin (CRM) involved (79% CRM positive post NACTRT/SCRT), 43% extramural venous invasion (n=33) and 36% signet ring histology. 62% had received prior NACTRT and 38% had received SCRT with chemotherapy before receiving mFOLFIRINOX. The most common grade 3 and grade 4 treatment related side effects included diarrhoea (7%), anaemia (4%) and infections (4%). Intended duration of mFOLFIRINOX or beyond was completed in 94% of patients. 60% of patients underwent curative local resection with R0 resection rates of 100% (n=28) and pathological complete response rates of 21%. The most common surgeries done were exenterations and abdominoperineal resections in 22% and 17% patients respectively. With a median follow up of 19 months, 25 patients had recurred or progressed for a median EFS of 20 months [95% confidence interval (CI): 15-24] while median overall survival was 55 months (95% CI: 24-86). Conclusions: Locally advanced rectal cancers with high-risk characteristics are a niche group of cancers with less-than-optimal outcomes post standard neoadjuvant strategies. mFOLFIRINOX appears to be well tolerated in this cohort of patients and enables conversion to curative local resection and potentially improves survival as well.

Development of a compact alpha and beta camera for dismantlement applications

A new method has been developed to image surface contamination on-site by short range radiation emitters (such as alpha or beta particle emitters). The measurement is performed in direct contact with the contaminated surface and uses a solid scintillator coupled with Silicon Photomultiplier arrays. A proof of principle is performed in laboratory using a simple prototype and multiple alpha and beta calibrated sources. The experimental setup used to acquire the data, as well as the analysis procedure, are described and the detection results and the image reconstruction are discussed with regard to dismantling requirements.

Micro-perforation of the diffusion media for polymer electrolyte membrane fuel cells using short and ultrashort laser pulses

The water management within polymer electrolyte membrane fuel cells is one of the main challenges limiting their extensive commercial application. By introducing directed pores in the carbon-based diffusion media, the water transport properties can be improved. Thus, the performance at demanding operating conditions and the lifetime of the fuel cell can be enhanced. In this work, the microporous layer of a diffusion media was perforated by locally ablating material using short and ultrashort-pulsed laser radiation with infrared wavelength. The influence of the pulse duration as well as the peak pulse fluence and the number of pulses on the ablation rate and the surface quality was evaluated. Laser scanning microscopy was applied to assess the topography of the micro-drillings. The heat-affected zone around the micro-drillings was investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The impact of short and ultrashort pulse laser radiation on the hydrophobic binder within the microporous layer was studied. Results showed a decreased binder evaporation in the vicinity of the micro-drillings by a reduction of the pulse length from the nanosecond to the picosecond range.

Short daily ultraviolet exposure enhances intrinsic water-use efficiency and delays senescence in Micro-Tom tomato plants.

Ultraviolet (UV) radiation, unless present at high doses, is recognised as a regulator of plant growth and some specific processes. The present study investigated the influence of short daily UV irradiation (15min/day, 11days) on leaf gas exchange and some biochemical and molecular markers of leaf senescence (such as stomata movements, chlorophyll breakdown, anthocyanin production, senescence-associated genes) in Micro-Tom tomato plants. The UV-induced reduction of g s (stomatal conductance) during the treatment was associated with the modified expression of some genes involved in the control of stomatal movements. We hypothesise a two-step regulation of stomatal closure involving salicylic and abscisic acid hormones. The temporal changes of g s and A net (net photosynthetic CO2 assimilation rate) along with the pigment behaviour, suggest a possible delay of leaf senescence in treated plants, confirmed by the expression levels of genes related to senescence such as SAG113 and DFR . The UV potential to induce a persistent partial inhibition of g s without severely affecting A net led to an increased iWUE (intrinsic water-use efficiency) during the 11-day treatment, suggesting a priming effect of short daily UV radiation towards drought conditions potentially useful in reducing the excess water use in agriculture.

Investigation of Proton Irradiation-Enhanced Device Performances in AlGaN/GaN HEMTs

We have studied the effects of proton irradiation on the AlGaN/GaN HEMTs with AlN buffer layer as well as conventional GaN buffer layer. It was found that a short time proton irradiation (~ 50 sec) can promote beneficial effects on device performances, which results in great reduction in the off-state leakage current and the gate leakage current without degrading the output current and transconductance. The pulsed I-V measurement demonstrated that both devices exhibit greatly improved current dispersion characteristics and, particularly, the device with AlN buffer layer shows stronger radiation hardness than that of the device with GaN buffer layer. These interesting results are believed to be due to the hydrogen passivation with thermal annealing effect during the proton irradiation. It is expected that the proper irradiation condition such as fluence, energy, and time is crucial to improve the device performances, rather than to deteriorate the performances.

Effects of superposition of 532 nm and 1064 nm wavelengths in copper micro-welding by pulsed Nd:YAG laser

Unstable and low absorption of laser energy is experienced in copper welding at around 1000 nm wavelength. At 532 nm wavelength, there is stable and high laser absorption by copper. Past researches have shown that transitional processing condition between keyhole and heat conduction welding results in a stable micro-welding process characterized by good surface quality and deep penetration. In order to adapt laser welding to copper using pulsed Nd:YAG lasers, investigations of welding quality and efficiency were addressed. Processing was done under transitional processing condition between heat conduction and keyhole welding. Copper C1020 specimens were processed using superposed laser wavelengths of 1064 nm and 532 nm. Effects of irradiation delay and power density on the process were clarified by taking measurements of molten volumes, and by analyzing the weld beads. In addition, the dynamics of molten area and keyhole formation were investigated through three-dimensional FEM analysis. A stabilized laser absorption and increased molten volume was achieved by superposition using 532 nm laser of an appropriate high power density coupled with a short irradiation delay for the 1064 nm laser, which resulted in high-efficiency welding of copper.

Применение неохлаждаемых микроболометров для регистрации импульсного терагерцового и инфракрасного излучения

Analytical relations for temperature response of the bolometer to periodic radiation pulses are obtained. It is theoretically shown and experimentally confirmed by the example of infrared bolometers that when detecting short radiation pulses, in contrast to the case of constant radiation, increasing the thermal conductivity of the bolometer and, accordingly, decreasing its thermal relaxation time, it is possible to significantly increase the response rate of the receiver, practically without reducing its sensitivity. The possibility of effective registration of pulsed terahertz radiation by microbolometers with a resistively coupled, thermally non-isolated antenna is considered. It is shown that such bolometers, which have increased thermal conductivity and, accordingly, reduced sensitivity to continuous-wave radiation, can be highly effective when detecting pulsed radiation with a duration shorter than the thermal relaxation time of the bolometer. On their basis, uncooled matrix detectors of pulsed terahertz radiation, characterized by a minimum detectable energy of less than 110-12 J and a frame rate of up to 1000 Hz, can be developed.

Application of uncooled microbolometers for detecting pulsed terahertz and infrared radiation

Analytical relations for temperature response of the bolometer to periodic radiation pulses are obtained. It is theoretically shown and experimentally confirmed by the example of infrared bolometers that when detecting short radiation pulses, in contrast to the case of constant radiation, increasing the thermal conductivity of the bolometer and, accordingly, decreasing its thermal relaxation time, it is possible to significantly increase the response rate of the receiver, practically without reducing its sensitivity. The possibility of effective registration of pulsed terahertz radiation by microbolometers with a resistively coupled, thermally non-isolated antenna is considered. It is shown that such bolometers, which have increased thermal conductivity and, accordingly, reduced sensitivity to continuous-wave radiation, can be highly effective when detecting pulsed radiation with a duration shorter than the thermal relaxation time of the bolometer. On their basis, uncooled matrix detectors of pulsed terahertz radiation, characterized by a minimum detectable energy of less than 1·10-12 J and a frame rate of up to 1000 Hz, can be developed. Keywords: microbolometer, pulsed terahertz radiation, antenna.

TOR promotes guard cell starch degradation by regulating the activity of β-AMYLASE1 in Arabidopsis.

Starch is the main energy storage carbohydrate in plants and serves as an essential carbon storage molecule for plant metabolism and growth under changing environmental conditions. The TARGET of RAPAMYCIN (TOR) kinase is an evolutionarily conserved master regulator that integrates energy, nutrient, hormone, and stress signaling to regulate growth in all eukaryotes. Here, we demonstrate that TOR promotes guard cell starch degradation and induces stomatal opening in Arabidopsis thaliana. Starvation caused by plants growing under short photoperiod or low light photon irradiance, as well as inactivation of TOR, impaired guard cell starch degradation and stomatal opening. Sugar and TOR induce the accumulation of β-AMYLASE1 (BAM1), which is responsible for starch degradation in guard cells. The plant steroid hormone brassinosteroid and transcription factor BRASSINAZOLE-RESISTANT1 play crucial roles in sugar-promoted expression of BAM1. Furthermore, sugar supply induced BAM1 accumulation, but TOR inactivation led to BAM1 degradation, and the effects of TOR inactivation on BAM1 degradation were abolished by the inhibition of autophagy and proteasome pathways or by phospho-mimicking mutation of BAM1 at serine-31. Such regulation of BAM1 activity by sugar-TOR signaling allows carbon availability to regulate guard cell starch metabolism and stomatal movement, ensuring optimal photosynthesis efficiency of plants.

Microwave-assisted catalytic pyrolysis of refuse-derived fuel (RDF) to improve pyrolysis performance and biochar properties

This paper investigated the feasibility of microwave-assisted catalytic pyrolysis (MACP) of refuse-derived fuel (RDF) to produce high quality biochar for the first time. Two main catalysts, K2CO3 and K3PO4, and their combination with bentonite or clinoptilolite were selected to mix with RDF in a fixed bed reactor exposed to microwave radiation. By comparing heating rate and biochar properties, the promising catalyst was identified as 20 wt% K2CO3 + 10 wt% bentonite due to its high heating rate (163 °C/min) and large specific surface area (264 m2/g) of biochar obtained under relatively low temperature (500 °C) and short microwave radiation time (30 min), much higher than previously reported values of RDF derived biochar (6–25 m2/g). K2CO3 showed higher heating rate and larger specific surface area of biochar than that of K3PO4 due to its prominent activation effect. Synergistic effect was observed when bentonite or clinoptilolite was added into K3PO4 which significantly improved microwave heating rate. Biochar produced from K2CO3 acts as a potential sorbent for retaining heavy metals in the biochar and soil due to its better porosity, while K3PO4 remaining in the biochar serves as essential nutrients for plant growth.

Shorter Radiation

Shorter Radiation

Effect of moisture on concrete damage and aggregate recycling under microwave irradiation

Microwave-assisted concrete aggregate recycling is a novel green technology, which causes less pollution and generates low energy during heating. This study aimed to explore the influence of moisture content on the heating process of concrete as well as its strength under microwave irradiation. Interfacial debonding of aggregate and mortar after the microwave irradiation was analyzed. Through a uniaxial compression experiment, the compressive strength of test blocks with different moisture contents is gained after microwave irradiation. The changes of microstructure are obtained using Scanning Electron Microscopy analysis. The results demonstrated that microwave power and moisture content were two important factors affected the concrete breaking. When the moisture content of the test block is relatively high, the concrete will break with a short irradiation time and low temperature under a high microwave power input. The aggregate–mortar interface separation was evident, and intact aggregates with low mortar adhesion could be picked out from the crushed concrete. In this study, we provided a reference for further development of microwave-assisted concrete recycling technology.