Short Radiation Research Articles

Association Between Up-front Surgery and Risk of Stroke in US Veterans With Oropharyngeal Carcinoma

Cardiovascular events are an important cause of morbidity in patients with oropharyngeal squamous cell carcinoma (OPSCC). Radiation and chemotherapy have been associated with increased risk of stroke; up-front surgery allows the opportunity for (chemo)radiotherapy de-escalation. To evaluate whether up-front surgery was associated with decreased stroke risk compared to nonsurgical treatment for OPSCC. This cohort study was conducted at the US Veterans Health Administration and examined US veterans diagnosed with nonmetastatic OPSCC from 2000 to 2020. Data cutoff was September 17, 2021, and data analysis was performed from October 2021 to February 2022. Up-front surgical treatment or definitive (chemo)radiotherapy as captured in cancer registry. Cumulative incidence of stroke, accounting for death as a competing risk; and association between up-front surgery and stroke risk. After generating propensity scores for the probability of receiving surgical treatment and using inverse probability weighting (IPW) to construct balanced pseudo-populations, Cox regression was used to estimate a cause-specific hazard ratio (csHR) of stroke associated with surgical vs nonsurgical treatment. Of 10 436 patients, median (IQR) age was 61 (56-67) years; 10 329 (99%) were male; 1319 (13%) were Black, and 7823 (75%) were White; 2717 received up-front surgery, and 7719 received nonsurgical therapy with definitive (chemo)radiotherapy. The 10-year cumulative incidence of stroke was 12.5% (95% CI, 11.8%-13.3%) and death was 57.3% (95% CI, 56.2%-58.4%). Surgical patients who also received (chemo)radiotherapy had shorter radiation and chemotherapy courses than nonsurgical patients. After propensity score and IPW, the csHR of stroke for surgical treatment was 0.77 (95% CI, 0.66-0.91). This association was consistent across subgroups defined by age and baseline cardiovascular risk factors. In this cohort study, up-front surgical treatment was associated with a 23% reduced risk of stroke compared with definitive (chemo)radiotherapy. These findings present an important additional risk-benefit consideration to factor into treatment decisions and patient counseling and should motivate future studies to examine cardiovascular events in this high-risk population.

EA2201: An ECOG-ACRIN phase II study of neoadjuvant nivolumab plus ipilimumab and short course radiation in MSI-H/dMMR rectal tumors.

TPS3644 Background: Trimodality therapy including chemoradiation, chemotherapy and surgical resection is standard for patients with T3-4 and/or node-positive (N+) rectal adenocarcinomas. Pathologic complete response (pCR) rates after neoadjuvant chemoradiation approach 15% in all-comers and 27% in patients with microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR) rectal cancer. Additionally, preclinical data suggest that hypofractionated radiation (large dose per fraction) may enhance immunogenicity. Given high response rates to immunotherapy in MSI-H/dMMR early stage and metastatic colorectal cancer (CRC), we hypothesized that neoadjuvant nivolumab plus ipilimumab and short course radiation in locally advanced MSI-H/dMMR rectal cancer (LARC) would result in increased pCR rates. Methods: EA2201 (NCT04751370) is an NCTN phase II clinical trial for patients with treatment-naïve locally advanced (T3-4Nx or TxN+) rectal adenocarcinoma that is dMMR or MSI-H. Patients receive nivolumab (480 mg) and ipilimumab (1 mg/kg) every 28 days for 2 cycles, followed by short course radiation (5 Gy x 5 fractions; total 25 Gy) and an additional 2 cycles of nivolumab and ipilimumab prior to disease reassessment and TME. The primary endpoint is pCR at TME. Secondary endpoints include 5-year disease-free survival, overall survival, treatment-related toxicities, and sphincter preservation rate for low-lying tumors. This study has a single-arm, two-stage design; a pCR rate of 50% or more will be taken as evidence of promising activity in this patient population. We plan to enroll 31 patients, with accrual currently ongoing. Clinical trial information: NCT04751370.

Association between up-front surgery and risk of stroke in U.S. veterans with oropharyngeal squamous cell carcinoma.

6057 Background: Cardiovascular disease and stroke are important causes of long-term morbidity and mortality in patients with oropharyngeal squamous cell carcinoma (OPSCC). Cancer treatments including radiotherapy to the neck and chemotherapy have been associated with increased risk of stroke. In the era of treatment de-intensification for OPSCC, up-front surgical treatment has been proposed as one strategy that allows for de-escalation or avoidance of (chemo)radiotherapy. We sought to quantify the cumulative incidence of stroke in patients treated for non-metastatic OPSCC, and then evaluate whether patients receiving up-front surgery for OPSCC have decreased risk of stroke compared to those undergoing non-surgical treatment. Methods: We identified a cohort of 10,436 United States veterans diagnosed with non-metastatic OPSCC from 2000-2020, of whom 2,717 received up-front surgery (with or without perioperative radiotherapy or chemoradiotherapy) and 7,719 received non-surgical therapy (definitive radiotherapy or chemoradiotherapy). We estimated the cumulative incidence of stroke in this population, accounting for death as a competing risk. To assess the association between up-front surgery and risk of stroke, we generated a propensity score for the probability of receiving surgical treatment and used inverse probability weighting to construct pseudo-populations balanced on all potential confounders. Cox regression models of the inverse probability weighted population were used to estimate the cause-specific hazard ratio of stroke associated with surgical vs non-surgical treatment. Results: The 10-year cumulative incidence of stroke was 12.5% (95% CI 11.8-13.23) and death was 57.3% (95% CI 56.2-58.4). Up-front surgical patients who underwent perioperative (chemo)radiotherapy had shorter radiation and chemotherapy courses compared to non-surgical patients, suggestive of lower treatment intensity. Propensity score generation and inverse probability weighting yielded good overlap and covariate balance between surgical and non-surgical treatment groups. The inverse probability weighted cause-specific hazard ratio of stroke associated with up-front surgical treatment was 0.77 (95% CI 0.66-0.91, p = 0.002). This association was consistent across subgroups defined by age ( > /≤65 years) and baseline cardiovascular risk factors (hypertension, hyperlipidemia, diabetes). Conclusions: In over 10,000 US veterans with OPSCC, cumulative incidence of stroke was 12.5% at 10 years. Up-front surgical treatment was associated with a 23% reduced risk of stroke compared to definitive (chemo)radiotherapy. These findings present an important additional risk-benefit consideration to factor into treatment decisions and patient counseling, and should motivate future studies to examine cardiovascular events in this high-risk population.

Improving the cloud initialization in WRF-Solar with enhanced short-range forecasting functionality: The MAD-WRF model

In spite of WRF-Solar being a numerical weather prediction (NWP) model specifically tailored for solar energy applications, the model lacks a specific cloud initialization component to improve short-range predictions. To overcome this limitation we have combined the fundamental concepts of the Multi-sensor Advection Diffusion nowCast (MADCast) model of using satellite observations to detect the clouds and advect and diffuse the clouds within a NWP model, with the better cloud–aerosol–radiation physics of WRF-Solar, into a new model referred to as MAD-WRF. The MAD-WRF cloud initialization combines a cloud parameterization that infers the presence of clouds based on relative humidity with observations of the cloud mask and cloud top/base height to provide a three-dimensional cloud analysis (liquid, ice, and snow hydrometeor content). During the forecasts, the hydrometeors can be advected and diffused with no microphysics, in what we refer to as the MAD-WRF passive mode. Alternatively, these passive hydrometeors can be integrated into the explicitly resolved hydrometeors during a nudging phase, designated the MAD-WRF active mode. In the nudging phase, there is a relaxation of the resolved hydrometeors towards the passive hydrometeors. Both modes aim to avoid an abrupt dissipation of clouds if the atmospheric environment is not adequate to support them. Both MAD-WRF active and passive modes as well as WRF-Solar have been run in a demonstration of MAD-WRF over the contiguous U.S., and results from these short-range forecasts (0–6 h) are presented here to illustrate the added value of MAD-WRF for global horizontal irradiance predictions. These results clearly illustrate the added value that MAD-WRF brings for short term irradiance predictions with the WRF-Solar model.

2H,13C-Cholesterol for Dynamics and Structural Studies of Biological Membranes.

We present a cost-effective means of 2H and 13C enrichment of cholesterol. This method exploits the metabolism of 2H,13C-acetate into acetyl-CoA, the first substrate in the mevalonate pathway. We show that growing the cholesterol producing strain RH6827 of Saccharomyces cerevisiae in 2H,13C-acetate-enriched minimal media produces a skip-labeled pattern of deuteration. We characterize this cholesterol labeling pattern by mass spectrometry and solid-state nuclear magnetic resonance spectroscopy. It is confirmed that most 2H nuclei retain their original 2H–13C bonds from acetate throughout the biosynthetic pathway. We then quantify the changes in 13C chemical shifts brought by deuteration and the impact upon 13C–13C spin diffusion. Finally, using adiabatic rotor echo short pulse irradiation cross-polarization (RESPIRATIONCP), we acquire the 2H–13C correlation spectra to site specifically quantify cholesterol dynamics in two model membranes as a function of temperature. These measurements show that cholesterol acyl chains at physiological temperatures in mixtures of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), sphingomyelin, and cholesterol are more dynamic than cholesterol in POPC. However, this overall change in motion is not uniform across the cholesterol molecule. This result establishes that this cholesterol labeling pattern will have great utility in reporting on cholesterol dynamics and orientation in a variety of environments and with different membrane bilayer components, as well as monitoring the mevalonate pathway product interactions within the bilayer. Finally, the flexibility and universality of acetate labeling will allow this technique to be widely applied to a large range of lipids and other natural products.

Electrochemical oxidation combined with UV irradiation for synergistic removal of perfluorooctane sulfonate (PFOS) in water

The effect of electrochemical degradation on Magnéli phase Ti4O7 anode combined with UV irradiation on the removal of PFOS was systematically evaluated in the present study. A synergistic effect of electrolysis and UV irradiation rather than a simple additive effect for PFOS degradation was demonstrated experimentally and theoretically. The short wavelength irradiation within 400 nm is the main contribution to enhance the electrochemical degradation of PFOS, while the initial pH of the solution has little effect on the PFOS degradation. The increase of current density accelerates the removal of PFOS either by electrolysis treatment or the joint process. The time-dependent density functional theory (TD-DFT) calculation indicates that the synergistic effect of the electrolysis and UV irradiation is most likely due to the involvement of the excited PFOS induced under UV irradiation in the electrochemical reaction. This study provides the first mechanistic explanation for the electrochemical degradation of PFOS enhanced by UV irradiation.

Modelling the interaction of the Astro Bio Cube Sat with the Van Allen’s Belt radiative field using Monte Carlo transport codes

PurposeThe AstroBio Cube Satellite (ABCS) will deploy within the inner Van Allen belt on the Vega C Maiden Flight launch opportunity of the European Space Agency. At this altitude, ABCS will experience radiation doses orders of magnitude greater than in low earth orbit, where CubeSats usually operate. The paper aims to estimate the irradiation effect on the ABCS payload in the orbital condition, their possible mitigation designing shielding solutions and performs a preliminary representativity simulation study on the ABCS irradiation with fission neutron at the TAPIRO (TAratura Pila Rapida Potenza 0) nuclear research reactor facility at ENEA.MethodsWe quantify the contributions of geomagnetically trapped particles (electron and proton), Galactic Cosmic Rays (GCR ions), Solar energetic particle within the ABCS orbit using the ESA’s SPace ENVironment information system. FLUKA (Fluktuierende Kaskade—Fluctuating Cascade) code models the ABCS interaction with the orbital source.ResultsWe found a shielding solution of the weight of 300 g constituted by subsequent layers of tungsten, resins, and aluminium that decreases on average the 20% overall dose rate relative to the shielding offered by the only satellite’s structure. Finally, simulations of neutron irradiation of the whole ABCS structure within the TAPIRO’s thermal column cavity show that a relatively short irradiation time is requested to reach the same level of 1 MeV neutron Silicon equivalent damage of the orbital source.ConclusionsThe finding deserves the planning of a future experimental approach to confirm the TAPIRO’s performance and establish an irradiation protocol for testing aerospatial electronic components.

Eliminating tattoos for short course palliative radiation therapy: Set-up error, satisfaction and cost

PurposePalliative patients are living longer thanks to advancements in systemic therapies and radiotherapy technologies. Prior to image guided radiotherapy, permanent ink tattoos were used to ensure set up accuracy. Permanent marks can cause psychological damage, physical pain and can reduce a patient’s quality of life. In recent years, image guided radiation therapy (IGRT) has become standard practice and may eliminate the need for permanent tattoos in this patient population. MethodsTwenty-five patients were consecutively chosen from the Palliative Radiation Oncology Program (PROP). Each received 5 fractions of radiotherapy commencing within 72 hours of CT simulation. In place of permanent tattoos, patients were marked with permanent marker and an adherent transparent film dressing (Tegaderm TM ) was placed over the mark. Patients were educated on maintaining the marks and dressing. Daily cone beam CT (CBCT) isocentre mismatch values were compared with 25 patients who received tattoos for radiotherapy to similar body regions. Radiation therapist concerns, cost, variations in isocentre shift values and additional imaging requirements were obtained. ResultsIsocentre shift values were similar (p<0.05) for Tegaderm TM vs. tattoo patients in the anterior-posterior (AP) and right-left (RL) directions. The mean shift value in the superior-inferior (SI) direction was larger for Tegaderm TM than for tattoos (p=0.01), however the magnitude was only 2 mm, which is clinically insignificant as these shifts were prior to IGRT guided correction. No patient required a repeat CBCT or a resimulation. The cost of the Tegaderm TM dressing was substantially less than the tattoo group. Radiation Therapists' satifaction with Tegaderm TM was overall high, however some expressed concerns with their durability and longevity. ConclusionsWe found that the use of Tegaderm TM dressing did not result in increased set-up time, mismatch error or additional imaging procedures (CBCT or CTsimulation) and moreover cost substantially less than permanent ink tattoos.

Light-sheet fluorescence microscopic probing of silicate materials

Abstract Light-sheet fluorescence microscopy (LSFM) is a powerful method for 3D characterization of fluorescent samples. In this contribution we introduce the technique for the application in material analytics by demonstrating the 3D imaging of Ce3+-doped YAG (Y3Al5O12) crystals isolated in a glass matrix. When excited with short wavelength laser radiation, the Ce3+ doping enables fluorescence in the wavelength range between about 450 nm and 680 nm. Since the excitation wavelengths of Ce3+ in the YAG and glass phases of the glass ceramic differ substantially, a suitable laser wavelength can be used to excite only the YAG phase. Thus, an imaging contrast to the surrounding glass matrix is generated. We exploit the crystal dendrites for monitoring the image contrast and improve it by a deconvolution operation of the images. This field of application of LSFM offers great potential, e. g. for fundamental understanding of the microstructuring processes in silicate glasses.

Radiation Therapy for Prostate Cancer Using HYpofractionation Directed by UltraSound (RAPHYDUS): A Brazilian Public Health Care System Study

PurposeThis study evaluated the toxicity associated with a short course dose-escalated hypofractionated radiation therapy (HFRT) using image guided RT with or without androgen suppression therapy in patients with prostate cancer. Methods and MaterialsThis single-center prospective observational study included 132 patients with prostate cancer from 2016 to 2020. Patients received HFRT using image guided RT (84%) with 3-dimensional (91%) or intensity modulated RT (9%). Total prescribed doses were 66 Gy (63%), 63 Gy (12%), and 60 Gy (24%) in 22, 21, or 20 daily fractions depending on organ-at-risk dose constraints. Acute toxicity was scored using Radiation Therapy Oncology Group criteria and the international prostate symptom index. The expanded prostate cancer index composite questionnaire was used to collect quality of life data (ranging from 0-100). ResultsThe study population consisted of 111 patients who completed RT during a period of 3 years. The risk groups were as follows: low risk (12%), intermediate (32%), and high (56%). None of the patients had suspicious lymph nodes. Ninety percent received androgen suppression therapy. Maximum acute genitourinary and gastrointestinal toxicity peaked at grade 3 in 4 of 111 evaluated patients (4%) and at grade 2 in 7 of 111 evaluated patients (8%), respectively. The average international prostate symptom score increased from 4.8 at pretreatment to 14.0 during week 4 and normalized (5.7) 3 months after treatment completion. ConclusionsThe current HFRT dose-escalation trial has demonstrated the feasibility of administering 66 Gy in 22 fractions with low acute gastrointestinal and genitourinary toxicities. Further follow-up will report late toxicities and outcomes.

COMPARISON OF DIFFERENT PREOPERATION RADIATION THERAPY SCHEMES FOR TREATMENT OF RECTAL CANCER DURING COVID-19 PANDEMIC

Rectal cancer stands on the fifth place in men and on the eighth in women in morbidity in Ukraine. Radiation therapy is one of the integral components in the process of rectal cancer treatment in patients with IIa and more severe stages. In present, there is still no definitive consensus about preoperation radiation therapy scheme. Both “long” course, which consists from 25-28 radiation fractions (45-50 Gy), and “short” one (5 fractions; 25 Gy) can be used for preoperation therapy. The aim of the study was to compare quality of long and short radiation therapy courses during treatment of patients with rectal cancer. 108 patients were enrolled in the study. Their diagnosis of rectal cancer was established during year 2020 by doctors of Municipal Enterprise «Poltava Regional Clinical Oncology Dispensary of Poltava Regional Council». The patients were divided in two groups according to radiation therapy regimen: I group “long course of radiation therapy” (n=64) got 25-28 fractions 5 Gy each (total dose 45-52 Gy); II group (n=44) was treated with shortcourse of radiation, which consisted of 5 fractions 5 Gy each. Only 73.4% (n=47) of patients have totally completed the course of radiation therapy in the I group. In contrast, the II group showed much better result with 95.4% of total completion (n=42; p=0.0042). Analysis of factors, which led to therapy disruption, showed, that the majority of patients discontinued the course for paramedic reasons. Toxicity of III and IV levels was registered only in 10.5% of patients (n=2), who have not got full radiation treatment. In 26.3% (n=5) of cases patients refused from further radiation therapy. About two thirds (63.2%; n=12) have not finished the course because of logistic restrictions connected with COVID-19 pandemic. According to obtained data, we believe that successful treatment of rectal cancer is possible only with complex applying of radiation therapy, chemotherapy and surgery. Short radiation therapy course is preferable during COVID-19 pandemic.

Safety of 222 nm UVC Irradiation to the Surgical Site in a Rabbit Model.

For the prevention of surgical site infection (SSI), continuous disinfection could be helpful. Short wavelength ultraviolet radiation C (UVC) is highly bactericidal but shows cytotoxicity. Radiation of UVC with a wavelength of 222 nm to the skin is considered to be safe because it only reaches the stratum corneum. However, the safety of 222 nm irradiation to the surgical field not covered with skin is unknown. The purpose of this study was to examine the safety of 222 nm UVC irradiation on a surgical field in a rabbit model. Five types of tissue were surgically exposed and irradiated with 222 or 254 nm UVC. Immunohistological assessment against cyclobutane pyrimidine dimer (CPD), an index of DNA damage by UVC, was performed. The CPD-positive cell rate was significantly higher in the 254 nm group than in the other groups in all tissues. A 222 nm group showed significantly more CPD than control in fat tissue, but no significant difference in all other tissues. In fat tissue collected 24 h after irradiation, the 254 nm group showed higher CPD than the other groups, while the 222 nm group had reduced to the control level. These data suggest that 222 nm UVC irradiation could be a new method to safely prevent SSI.

Ecological Impacts of Coral Reefs, Egyptian Red Sea Coast: Elemental Characterization and Spatial Distribution with INAA

ABSTRACT Instrumental neutron activation analysis (INAA) is a well-accepted technique that has the ability to simultaneously determining 30–40 elements. INAA is also capable of determining major, minor, and trace elements as well as rare earth elements. It was utilised to determine the concentration of heavy elements and elemental contents of coral reef samples collected from three locations on the Red Sea coast of Egypt. The coral reef samples were prepared with their standard materials and together irradiated in Egypt Second Research Reactor (ETRR-2). For short and long irradiations, samples were separately irradiated at a convenient thermal neutron flux 4 × 1011cm−2s−1 for 2 min in a pneumatic rabbit system and samples were irradiated at a thermal neutron flux 1.5x1014cm−2s−1 for 32 mins, respectively. All samples were counted two times in a HPGe detector with a relative efficiency of 100% for short and long irradiations. The following elements have been determined Al, Ti, Na, K, Mg, V, Cl, Ca, Mn, Cr, As, Co, Zn, Ni, Fe, Br, Tb, Zr, Hf, Sb, Ba, Sc, Nd, La, Sm, Ce, Eu, Yb, Ta, U, and Th. In the Quseir harbour, the maximum concentration of Al, Fe, Mn Zn, U, and Th were 3487 ± 74, 2007 ± 22, 33 ± 0.5, 119 ± 0.5, 4 ± 0.3, and 0.52 ± 0.04 mg/kg, respectively. These concentrations were higher for these elements compared to other areas. The present work is concerned to achieve precise information about the elemental content in coral reef samples along the Red Sea coast in specific locations and the effect of detected concentrations on the surrounding environment.

Donor-Acceptor Pyridinium Salts for Photo-Induced Electron-Transfer-Driven Modification of Tryptophan in Peptides, Proteins, and Proteomes Using Visible Light.

Tryptophan (Trp) plays a variety of critical functional roles in protein biochemistry; however, owing to its low natural frequency and poor nucleophilicity, the design of effective methods for both single protein bioconjugation at Trp as well as for in situ chemoproteomic profiling remains a challenge. Here, we report a method for covalent Trp modification that is suitable for both scenarios by invoking photo-induced electron transfer (PET) as a means of driving efficient reactivity. We have engineered biaryl N-carbamoyl pyridinium salts that possess a donor-acceptor relationship that enables optical triggering with visible light whilst simultaneously attenuating the probe's photo-oxidation potential in order to prevent photodegradation. This probe was assayed against a small bank of eight peptides and proteins, where it was found that micromolar concentrations of the probe and short irradiation times (10-60 min) with violet light enabled efficient reactivity toward surface exposed Trp residues. The carbamate transferring group can be used to transfer useful functional groups to proteins including affinity tags and click handles. DFT calculations and other mechanistic analyses reveal correlations between excited state lifetimes, relative fluorescence quantum yields, and chemical reactivity. Biotinylated and azide-functionalized pyridinium salts were used for Trp profiling in HEK293T lysates and in situ in HEK293T cells using 440 nm LED irradiation. Peptide-level enrichment from live cell labeling experiments identified 290 Trp modifications, with 82% selectivity for Trp modification over other π-amino acids, demonstrating the ability of this method to identify and quantify reactive Trp residues from live cells.

Applications of cone beam computed tomography in the field of prosthodontics: A review

Cone beam computed tomography (CBCT) is one of the latest radiographic modality available. It is use are enormous in medical and dental field. Among all CBCT is an essential commodity in the field of prosthodontics. The amazing capability of CBCT for providing sub-millimeter resolution in images of high diagnostic quality, with short scanning times (10–70 s) and radiation dosages reportedly up to 15–100 times lower than those of conventional Computed tomography scans are the unique features of CBCT. The aim of this article is to educate the Prosthodontist to CBCT technology, provide an overview of CBCT systems and review the specific application of various CBCT display modes to clinical Prosthodontics practice.

Photoredox catalysis powered by triplet fusion upconversion: arylation of heteroarenes

In this work, the feasibility of triplet fusion upconversion (TFU, also named triplet–triplet annihilation upconversion) technology for the functionalization (arylation) of furans and thiophenes has been successfully proven. Activation of aryl halides by TFU leads to generation of aryl radical intermediates; trapping of the latter by the corresponding heteroarenes, which act as nucleophiles, affords the final coupling products. Advantages of this photoredox catalytic method include the use of very mild conditions (visible light, standard conditions), employment of commercially available reactants and low-loading metal-free photocatalysts, absence of any sacrificial agent (additive) in the medium and short irradiation times. The involvement of the high energetic delayed fluorescence in the reaction mechanism has been evidenced by quenching studies, whereas the two-photon nature of this photoredox arylation of furans and thiophenes has been manifested by the dependence on the energy source power. Finally, the scaling-up conditions have been gratifyingly afforded by a continuous-flow device.Graphical abstract

A 265-Nanometer High-Power Deep-UV Light-Emitting Diode Rapidly Inactivates SARS-CoV-2 Aerosols.

ABSTRACTSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19) is an acute respiratory infection transmitted by droplets, aerosols, and contact. Controlling the spread of COVID-19 and developing effective decontamination options are urgent issues for the international community. Here, we report the quantitative inactivation of SARS-CoV-2 in liquid and aerosolized samples by a state-of-the-art, high-power, AlGaN-based, single-chip compact deep-UV (DUV) light-emitting diode (LED) that produces a record continuous-wave output power of 500 mW at its peak emission wavelength of 265 nm. Using this DUV-LED, we observed a greater-than-5-log reduction in infectious SARS-CoV-2 in liquid samples within very short irradiation times (<0.4 s). When we quantified the efficacy of the 265-nm DUV-LED in inactivating SARS-CoV-2, we found that DUV-LED inactivation of aerosolized SARS-CoV-2 was approximately nine times greater than that of SARS-CoV-2 suspension. Our data demonstrate that this newly developed, compact, high-power 265-nm DUV-LED irradiation system with remarkably high inactivation efficiency for aerosolized SARS-CoV-2 could be an effective and practical tool for controlling SARS-CoV-2 spread.IMPORTANCE We developed a 265-nm high-power DUV-LED irradiation system and quantitatively demonstrated that the DUV-LED can inactivate SARS-CoV-2 in suspensions and aerosols within very short irradiation times. We also found that the inactivation effect was about nine times greater against aerosolized SARS-CoV-2 than against SARS-CoV-2 suspensions. The DUV-LED has several advantages over conventional LEDs and mercury lamps, including high power, compactness, and environmental friendliness; its rapid inactivation of aerosolized SARS-CoV-2 opens up new possibilities for the practical application of DUV-LEDs in high-efficiency air purification systems to control airborne transmission of SARS-CoV-2.

Optical properties of copper naphthalocyanine nanoparticles prepared by laser ablation in liquid

Copper naphthalocyanine nanoparticles were successfully prepared by laser ablation in liquid. Micron-size copper naphthalocyanine powders were used as the raw material in water and were irradiated with a laser beam (Nd:YAG, SHG) to obtain nanoparticles. Nanoparticles were examined by scanning electron microscopy, dynamic light scattering, a spectrophotometer, and Raman spectroscopy. Even in the case of irradiation at low laser fluence and for short irradiation times, nanoparticles were obtained owing to the comparatively low threshold of laser ablation. Laser irradiation changed the crystal structure, but the composition of the nanoparticles was not altered by laser irradiation. The dispersion stability of nanoparticle solution was very high, and absorbance of the solution was almost constant without precipitation. The conversion rate from raw material to nanoparticle was 85.5%. The Grüneisen coefficient for the copper naphthalocyanine nanoparticles was also high; therefore, the produced copper naphthalocyanine nanoparticles were suitable as a contrast agent for photoacoustic imaging.

Fission product isotope ratios as event characterization tools Part I: Particulate debris, isotopic activity ratios

Abstract The main goal of this work is to develop quantitatively reliable tools that can be used to identify the origin of a nuclear event, e. g. discriminate between a nuclear explosion and an accidental reactor release. A model has been developed, which takes into account the wide range of conditions and parameters, which may exist in connection with nuclear events. Using the model, specific isotope activity ratios are defined, promising to be effective in event characterization, while reducing the influence of various nuclear scenarios to a minimum. Besides, an attempt was made to quantify the concept of “short irradiation reactor” and to set its limits, as related to an event characterization method.

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.