Effect Of Irradiation Research Articles

Effect of Heavy Ion Irradiation on Friction of GNSs: Implications for Aerospace Lubrication

Effect of Heavy Ion Irradiation on Friction of GNSs: Implications for Aerospace Lubrication

Effects of Photon versus Carbon-Ion Irradiation in the Rat Cervical Spinal Cord - a Serial T2 and Diffusion-weighted Magnetic Resonance Imaging Study.

Carbon-ion irradiation is increasingly used at the skull base and spine near the radiation-sensitive spinal cord. To better characterize the invivo radiation response of the cervical spinal cord, radiogenic changes in the high-dose area were measured in rats using magnetic resonance imaging (MRI) diffusion measurements in comparison to conventional photon irradiations. In this longitudinal MRI study, we examined the gray matter (GM) of the cervical spinal cord in 16 female Sprague-Dawley rats after high-dose photon (n = 8) or carbon-ion (12C) irradiation (n = 8) and in 6 sham-exposed rats until myelopathy occurred. The differences in the diffusion pattern of the GM of the cervical spinal cord were examined until the endpoint of the study, occurrence of paresis grade II of both forelimbs was reached. In both radiation techniques, the same order of the occurrence of MR-morphological pathologies was observed - from edema formation to a blood spinal cord barrier (BSCB) disruption to paresis grade II of both forelimbs. However, carbon-ion irradiation showed a significant increase of the mean apparent diffusion coefficient (ADC; P = 0.031) with development of a BSCB disruption in the GM. Animals with paresis grade II as a late radiation response had a highly significant increase in mean ADC (P = 0.0001) after carbon-ion irradiation. At this time, a tendency was observed for higher mean ADC values in the GM after 12C irradiation as compared to photon irradiation (P = 0.059). These findings demonstrated that carbon-ion irradiation leads to greater structural damage to the GM of the rat cervical spinal cord than photon irradiation due to its higher linear energy transfer (LET) value.

Experimental and modeling study on irradiation effect of A508-Ⅲ steel

Irradiation can induce microscopic defects in reactor pressure vessel (RPV) steel, resulting in macroscopic hardening and embrittlement. This paper proposes a micro‑meso-macroscale calculation framework for the mechanical properties of irradiated RPV steel based on experimental and numerical investigations. The mean size and number density of Fe-ion-irradiation-induced dislocation loops were measured using transmission electron microscopy (TEM). These parameters were described by a power-function relationship with the irradiation dose at various temperatures and were used as input parameters for the crystal plasticity finite element model (CPFEM). Nano-indentation tests of A508-Ⅲ steel under different irradiation conditions were successfully simulated. In addition, microstructural characterization and molecular dynamics (MD) simulations revealed the phenomenon of dislocation pinning and the sweeping of irradiation defects during dislocation migration, implying that the dislocation-loop interactions could be responsible for the formation of dislocation channels and curved dislocation lines. Furthermore, increase in yield stress and the ductile-brittle transition temperature (DBTT) at various temperatures were investigated. Results indicated that yield stress, DBTT, and the degree of irradiation hardening and embrittlement increased with the irradiation dose and decreased with irradiation temperature. Finally, the adjusted reference temperature (ART), a significant design parameter for nuclear reactors, was calculated and evaluated using the multiscale framework. The framework can serve as a reference text for extending the life of nuclear reactors.

Phenology and the response of photosynthesis to irradiance and temperature gradient in the herbal drug red alga, Chondria armata (Rhodomelaceae, Ceramiales) from Kagoshima, Japan

AbstractSeasonal changes in the size of the herbal drug red alga Chondria armata (Rhodomelaceae, Ceramiales) were investigated in Kagoshima, Japan, which is near the northern distributional limit in the western Pacific. Additionally, its photosynthetic response to irradiance and temperature was examined using dissolved oxygen sensors and a pulse amplitude modulation (PAM)-chlorophyll fluorometer. This alga was observed in tidepools throughout the year; its height and weight were greatest in December and the lowest in April and May. The net photosynthesis of the photosynthesis–irradiance (P–E) curve determined at 28°C quickly saturated at 113 µmol photons m-2 s-1, with minimal inhibition even at 1000 µmol photons m-2 s-1. The gross photosynthesis of the photosynthesis–temperature (P–T) curved over 8 to 40°C, measured at 500 µmol photons m-2 s-1, peaked at 30.1°C and decreased rapidly below 20°C and above 36°C, respectively. Similarly, the effective quantum yield (ΔF/Fm') after a 3-day culture during 4–40°C at 50 µmol photons m-2 s-1 remained stable between 16°C and 32°C but decreased outside of this range. The combined effect of irradiance (200 [low] and 1000 [high] µmol photons m-2 s-1) and temperature (28, 22, and 16°C) revealed that ΔF/Fm' declined during exposure to high irradiance at all temperature treatments. However, it mostly recovered after a subsequent 12-hour period of dim-light acclimation at 28°C and 22°C. In contrast, those at 16°C could not recover, indicating the occurrence of low-temperature light stress. This alga appears to be well-adapted to the irradiance and temperature environment at the study site. However, the winter temperature appears to approach its threshold level, and the occurrence of strong light during the winter might adversely affect the abundance of this alga near its northern distributional limit.

The Effects of Irradiation on Structure and Leaching of Pure and Doped Thin-Film Ceria SIMFUEL Models Prepared via Polymer-Templated Deposition

When studying hazardous materials such as spent nuclear fuel (SNF), the minimisation of sample volumes is essential, together with the use of chemically-similar surrogates where possible. For example, the bulk behaviour of urania (UO2) can be mimicked by appropriately-engineered thin films of sufficient thickness, and inactive materials such as ceria (CeO2) can be used to study the effects within radioactive systems used to fuel nuclear fission. However, thin film properties are sensitive to the preparative method, many of which require the use of highly toxic precursors and specialised apparatus (e.g., chemical vapour deposition). To address this, we present the development of a flexible, tuneable, scalable method for the preparation of thin-film CeO2 SIMFUEL models with a thickness of ≈5 μm. The effects of γ irradiation (up to 100 kGy) and dopants including trivalent lanthanides (Ln3+) and simulant ε-particles on the structure and long-term leaching of these systems under SNF storage conditions were explored, alongside the context of this within further work. It was found that the sensitivity of CeO2 films to reduction upon irradiation, particularly in the presence of simulant ε-particles, resulted in increased leaching of Ce (as CeIII), while trivalent lanthanides (Nd3+ and Eu3+) had a minimal effect on Ce leaching.

An investigation into the effect of UV irradiation and biofilm colonization on adsorption and desorption behavior of polyurethane (PU) microplastics for bisphenol A (BPA)

Recent studies have demonstrated that microplastics (MPs) can act as a transport vector for pollutants in the environment. However, most studies have focused on carbon-carbon backbone polymers, with little known about heteroatom backbone polymers. In this study, polyurethane (PU) MPs were modified by UV irradiation and microorganism colonization to assess the different aging treatments on the interaction behavior (adsorption/desorption) between PU MPs and bisphenol A (BPA). The results of the adsorption kinetics experiment illustrated that the adsorption process of BPA could be described well by a pseudo-second order kinetic equation on both fresh and aged PU MPs. Although fresh PU MPs revealed the highest saturated adsorption capacity, at low BPA exposure concentrations (≤ 100 μg/L) the adsorption capacities for UV aged and biofilm colonized PU MPs were very similar to fresh MPs or even slightly higher than for fresh MPs, the main adsorption mechanisms including H-bonding interactions and π–π interactions. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) investigations suggested obvious physicochemical property changes (e.g., generation of new functional groups, erosion, etc.) after UV irradiation and biofilm colonization. This study also showed that different exposure environments (ultrapure water, artificial seawater, simulated gastric fluid) could affect BPA adsorption/desorption via hydrophobic and electrostatic interaction on PU surfaces. These results further clarify the adsorption mechanisms of BPA on PU MPs that have undergone different aging treatments, and provides a theoretical basis for the assessment of environmental behavior and exposure risks when PU MPs and BPA coexist.

Lipidomics of Microplasma-Irradiated Cells at Optimized Discharge Conditions for the Absorption of High-Molecule Drug

Microplasma irradiation is a promising technique for the transdermal delivery of high-molecular-weight drugs. In this technique, microplasma components interact with the skin surface or cell membranes, allowing the drugs to penetrate. For efficient and safe drug delivery, it is crucial to understand these interactions. To this end, this study investigated the effects of microplasma irradiation on cellular lipids, particularly those associated with cell membranes. Rat intestinal epithelial cells were treated with microplasma irradiation at two different voltages (4.0 kV or 4.5 kV). An untargeted lipidomic was conducted using liquid chromatography–mass spectrometry (LC/MS) technique. The results revealed that microplasma irradiation at 4.0 kV induces a significant increase in cell membrane lipids within 10 min post-irradiation. All major cell membrane lipids, including phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin, exhibited increases of over 25% within this short timeframe. Notably, this effect is transient, as lipid levels return to their baseline after 12 h. Furthermore, no significant differences in live and apoptotic cell percentages were observed between the control and 12 h post-irradiated cells. In contrast, irradiation at 4.5 kV did not elicit significant changes in cell membrane lipids, correlating with the absence of drug absorption under this condition. Hence, our study unveiled a correlation between the rapid increase in cell membrane lipids and enhanced drug absorption in microplasma-irradiated cells. This lipid augmentation potentially enhances membrane fluidity and permeability, thus facilitating drug absorption. Beyond elucidating the mechanisms and safety of microplasma-based drug delivery, our research provides valuable insights for advancing various microplasma-based biomedical technologies.

Effect of hydrogen, helium and dose rate on the evolution of dislocation loop in pure iron during in-situ ion irradiation

Simulating neutron irradiation with ion irradiation requires considering the comprehensive effects of hydrogen, helium and dose rate to fully understand the microstructure evolution of material in an irradiation environment. Here, the characterization and evolution of dislocation loops in pure iron were investigated under heavy ion irradiation with four different injected gas ion types (Fe+, Fe++H2+, Fe++He+and Fe++H2++He+) and under dual-beam (Fe++He+) irradiation with four different dose rates using in-situ transmission electron microscopy at 723 K. Comparing to the single-beam (Fe+) irradiation, the additional injection of H or He, or co-injected H and He, mainly promoted the nucleation of dislocation loops at the early stage of irradiation and enhanced loop growth after that. Among them, the simultaneous irradiation of triple beams (Fe++H2++He+) was most pronounced. Moreover, triple-beam (Fe++H2++He+) irradiation resulted in the highest ratio of the rotation of loop habit-plane. Under dual-beam (Fe++He+) irradiation, the results demonstrated that as the dose rate increased, the loop density increased and the loop size decreased. Moreover, the fraction of 〈100〉 loops at low dose rate was noticeably greater than that at high dose rate. The results of the current work provide important references for a better understanding of the effectiveness of ion irradiation in simulating neutron irradiation.

Electron irradiation effects on the optical properties of Hf- and Zn-doped β-Ga2O3

Optical and electrical properties of Hf- and Zn-doped β-Ga2O3 samples, which are n-type and insulating, respectively, were altered via high-energy electron irradiation at 2.5 or 0.5 MeV. The β-Ga2O3:Hf samples irradiated with 2.5 MeV electrons experienced a color change from blue to yellow and a large drop in conductivity, attributed to the creation of gallium vacancies, which compensate donors. This irradiation resulted in the absence of free carrier absorption and the presence of Cr3+ photoluminescence (PL). PL mapping prior to irradiation revealed optically active ZnO precipitates that formed during the growth of β-Ga2O3:Zn. These precipitates have a 384 nm (3.23 eV) stacking fault emission in the core; in the outer shell of the precipitate, the PL blue-shifts to 377 nm (3.29 eV) and a broad defect band is observed. After 0.5 MeV electron irradiation, the defect band broadened and increased in intensity. The blue PL band (435 nm) of β-Ga2O3 was enhanced for both Hf- and Zn-doped samples irradiated with 0.5 MeV. This enhancement is correlated with an increase in oxygen vacancies.

Reduced interface effect of proton beam irradiation on the electrical properties of WSe2/hBN field effect transistors

Two-dimensional transition metal dichalcogenide (TMDC) semiconductors are emerging as strong contenders for electronic devices that can be used in highly radioactive environments such as outer space where conventional silicon-based devices exhibit nonideal characteristics for such applications. To address the radiation-induced interface effects of TMDC-based electronic devices, we studied high-energy proton beam irradiation effects on the electrical properties of field-effect transistors (FETs) made with tungsten diselenide (WSe2) channels and hexagonal boron-nitride (hBN)/SiO2 gate dielectrics. The electrical characteristics of WSe2 FETs were measured before and after the irradiation at various proton beam doses of 1013, 1014, and 1015 cm−2. In particular, we demonstrated the dependence of proton irradiation-induced effects on hBN layer thickness in WSe2 FETs. We observed that the hBN layer reduces the WSe2/dielectric interface effect which would shift the transfer curve of the FET toward the positive direction of the gate voltage. Also, this interface effect was significantly suppressed when a thicker hBN layer was used. This phenomenon can be explained by the fact that the physical separation of the WSe2 channel and SiO2 dielectric by the hBN interlayer prevents the interface effects originating from the irradiation-induced positive trapped charges in SiO2 reaching the interface. This work will help improve our understanding of the interface effect of high-energy irradiation on TMDC-based nanoelectronic devices.

Sharp Rise in Cosmic Ray Irradiation of Organisms on Earth Caused by a Nearby SN Shockwave Passage.

The work considers the modelling of nearby supernova (SN) effects on Earth's biosphere via cosmic rays (CRs) accelerated by shockwaves. The rise of the radiation background on Earth resulted from the external irradiation by CR high-energy particles and internal radiation in organisms by the decay of cosmogenic 14C is evaluated. We have taken into account that the CR flux near Earth goes up steeply when the shockwave crosses the Solar System, while in previous works the CR transport was considered as purely diffusive. Our simulations demonstrate a high rise of the external ionization of the environments at Earth's surface by atmospheric cascade particles that penetrate the first 70-100 m of water depth. Also, the cosmogenic 14C decay is able to irradiate the entire biosphere and deep ocean organisms. We analyzed the probable increase in mutation rate and estimated the distance between Earth and an SN, where the lethal effects of irradiation are possible. Our simulations demonstrate that for SN energy of around 1051 erg the lethal distance could be ∼18 pc.

The dazzling/damage mechanism of InGaAs detectors by near-infrared continuous laser

To investigate the dazzling/damage mechanism of InGaAs detectors by continuous laser, InGaAs detectors irradiated by continuous laser were analyzed theoretically and verified experimentally. Constructing the dazzling model of InGaAs detectors, saturated pixel data at different power levels were obtained. After comparing these data with verified experiments, it was observed that the magnitude and regularity of saturated pixel were relatively consistent at the same power levels. A finite element theoretical model of laser-irradiated InGaAs detectors was designed by Comsol. After calculation, the corresponding laser damage threshold for InGaAs detector was about 9.13 × 105 W/cm2 and 2.63 × 105 W/cm2 for irradiation times of 40 ms and 400 ms, respectively. These values were in relatively good agreement with the experimentally obtained damage thresholds of 1.07 × 106 W/cm2 and 3.95 × 105 W/cm2. The verified experiments confirmed the validity of the simulation methods and the dazzling/damage model employed in this paper. This study serves as a reference for further research on the laser irradiation effects and damage mechanisms of InGaAs detectors, as well as for laser protection and performance optimization in imaging systems.

Study on Radiation Damage of Silicon Solar Cell Electrical Parameters by Nanosecond Pulse Laser

This experimental study investigates the damage effects of nanosecond pulse laser irradiation on silicon solar cells. It encompasses the analysis of transient pulse signal waveform characteristics at the cells’ output and changes in electrical parameters, such as I–V curves before and after laser irradiation under varying laser fluence and background light intensities, and explores the underlying action mechanisms of laser irradiation. The study reveals that as the laser fluence increases up to 4.0 J/cm2, the peak value of the transient pulse signal increases by 47.5%, while the pulse width augments by 88.2% compared to the initial transient pulse signal. Furthermore, certain parameters, such as open-circuit voltage, short-circuit current, and peak power obtained, from the measured I–V curve indicate a threshold laser fluence for functional degradation of the solar cell at approximately 1.18 ± 0.42 J/cm2. Results obtained from laser irradiation under different background light intensities underscore the significant influence of background light on laser irradiation of silicon cells, with the most severe damage occurring in the absence of light. Moreover, findings from laser irradiation at multiple locations on the silicon cell demonstrate a linear decrease in the output voltage of the silicon cell with an increase in the number of irradiation points.

Analysis of night behavior and negative running for PVT system

High absorption of PV benefits heat collection in the daytime, but the heat loss to the space/environment because of its high emissivity also should be noticed. Although there are many papers investigating PVT, few of them cover the night behavior and negative running during late afternoon. This paper supplements detailed studies on related content to draw people's attention to the night and late-afternoon operation that helps better strategy establishment and less heat loss. From experiments, the clouds help hinder the PV radiant heat exchange with space. Under clear night, the PV bottom temperature can be 6.88 °C lower than air temperature and the water tank's bottom temperature drops 2.8 °C. Because of the fluid viscosity, no apparent temperature stratification and flow occur in the PVT water pipe, causing even PV temperature. The higher the water temperature, the easier the negative running occurs during late afternoon, although the irradiation is still high at 521W/m2. Heat loss power and energy are −199W and 1791 KJ from 15:10 to 17:40. Based on different regressed linear correlations of different PVT systems, the effect of water temperature, irradiation, and ambient temperature on the negative performance is also comparatively studied.

The Effects of Irradiation on the Improvement in Oxidation Behavior of MX-ODS Steel in Liquid Pb.

Lead-cooled fast reactors exhibit strong inherent safety performance and good economic features, while material degradation due to corrosion and irradiation is still challenging. Oxide dispersion-strengthened steels are one of the promising candidates for fuel cladding materials. The effects of both irradiation and corrosion on ODS steel need to be further studied. In this work, MX-ODS steel was irradiated by Fe ions at 500 °C up to 46 dpa. Later, the as-received specimen and the irradiated specimen were used to conduct corrosion tests in oxygen-saturated Pb at 550 °C for 1 h. In the as-received specimen, discontinuous oxides penetrated by Pb and Pb in contact with steel matrix were observed, demonstrating unsatisfactory corrosion resistance of the material. However, in the irradiated specimen after corrosion experiment, a protective oxide layer formed and prevented Pb attack. The oxidation behavior differences between the two specimens can be attributed to the defects produced by irradiation and the structural discrepancy in oxides caused by the formation process. A possible mechanism of irradiation on the corrosion is discussed. In the as-received specimen, Fe atoms loss led to voids in the oxides, and lead penetrated the oxides through these voids. In the irradiated specimen, defects left by previous irradiation helped to form a more uniform oxide layer. The adhesive outer magnetite oxide and the Fe ions generated from where grain boundary oxidation developed retarded the presence of voids and made the oxide layer protective.

Effects of UV-C exposure on composite materials made of recycled carbon fibers

Carbon fiber-reinforced polymers are widely used in space applications since they combine outstanding mechanical properties with low material density. However, the development of composite components involves raw materials that are becoming increasingly scarce and contributes significantly to carbon emissions during the manufacturing process. Indeed, the fabrication of fibers is energy-intensive and requires very high temperatures, high costs, and usually precursor materials derived from fossil fuels. In addition to the negative environmental impact due to the manufacturing process, there are critical issues related to the disposal of components fabricated using carbon/glass fiber composites. Therefore, the use of efficient recycling strategies becomes necessary, according to economic reasons and legislation. The recycled fibers exhibit different properties from virgin fibers, generally lower, due to adverse effects of the current recycling methods. In this study, we investigated the potential application of recovered carbon fibers in satellite platforms, using recycled fibers from our laboratory obtained with a subcritical solvolysis method that we have previously developed. Composite materials reinforced with recycled and virgin carbon fibers were exposed to UV-C, and the effects of irradiation were analyzed in terms of structural performance, surface morphology, and chemical modifications of the samples. Results were used to evaluate the possibility of effectively using recycled fibers in space applications, without significant loss of performance.

Capture enhanced neutron irradiation for the treatment of the Alzheimer Disease: Micro-nanodosimetric characterization of beta amyloid peptide samples

Alzheimer Disease (AD) is the most common cause of dementia. 46.8 million people live with AD worldwide, with numbers projected to almost double every 20 years. The etiological mechanisms underlying the neuropathological changes in AD remain unclear. The beta amyloid peptide Aβ is considered to be the main culprit of the pathological processes. NECTAR (NEutron Capture-enhanced Treatment of neurotoxic Amyloid aggRegates) project proposes an alternative and revolutionary strategy to address AD, investigating the safety, feasibility and effectiveness of a Capture-Enhanced Neutron Irradiation to structurally damage Aβ aggregates, by exploiting capture agent vectors containing B-10 and Gd-157.Among many others, one of the goals of the project is to perform calculations and measurements of microdosimetric and nanodosimetric quantities to characterize the effect of reaction products at local level and to link it to the fibrils depolymerization process. In this framework, a new low-pressure tissue-equivalent proportional counter (TEPC) was designed and developed. The system is a wall-free TEPC able to measure micro-nanometric dose deposition for different biological samples. It is characterized by two main features: i) a wall-less structure allows the charged particles produced by the sample to access the sensitive volume, where their effects are studied; ii) a trigger system enables the assessment of the number of ionizations induced in the sensitive volume related to a single primary particle for obtaining nandosimetric information.The prototype system was tested in the PGNAA (Prompt Gamma Neutron Activation Analysis) facility of the LENA reactor (Pavia) to directly study secondary particles from Aβ fibrils, loaded with Boron. Results of the micro-nanodosimetric characterization of high LET secondaries from Aβ-fibrils were compared to a reference Boron sample. For a 500 nm simulated site size, the presence of Boron in the Aβ sample greatly populates microdosimetric spectra at high lineal energy values. Instead, lower LET particles (photons, protons) from reactions on the other Aβ aggregate solution molecules populate the low lineal energy portion of the distribution.The nanodosimetric distributions highlights the presence of different field components on the nanodosimetric spectra: low LET particles (protons/electrons) produce small ionization clusters, while alpha and Lithium ions induce larger clusters, thus have a higher biological effect. The nanodosimetric measurements have been compared with Monte Carlo simulations performed with a track-structure code, showing a good agreement.This multi-level approach provides a deeper physical understanding of the mixed secondaries field coming from B-enriched target, as well as a reference for the biological effect on Aβ fibrils at nanometer level. These preliminary measurements represent the first microdosimetric and nanodosimetric characterization of the secondary mixed field directly emitted by a biological sample irradiated with neutrons.

Impact of Alpha Rays on the Optoelectronic Properties of Epoxy Resin Thick Films

Irradiated epoxy thick films are important for optical properties and may be used in many optical applications. This study aims to evaluate the effect of alpha irradiation on the optical and structural properties of epoxy thick films. Epoxy resin films were prepared by mixing epoxy resin (A) with hardener (B) at a mixing ratio of 3:1. Thus, specific thick films with thicknesses of 0.7 mm,0.8 mm and 1 mm were manufactured. Using visible and ultraviolet spectroscopy is one of the most important methods for studying polymers band gaps and electrical properties. The absorbance and transmittance spectra were used to investigate the optical properties of epoxy coatings of different thicknesses over a wavelength range of 300 nm–900 nm. Optical properties, such as absorption coefficient, refractive index, extinction coefficient, real dielectric constant, imaginary dielectric and optical band gap, were measured. The results show that the epoxy thick films have good optical transparency in the low-wavelength region. The results showed that increasing the thickness of the resin films decreased the optical energy gap and refractive index while increasing the absorption and extinction coefficients. In comparison, the effect of irradiation on an epoxy film of thickness 1 mm leads to an increase in the transmittance spectrum and energy gap and a decrease in the optical constants. The Fourier-transform infrared (FTIR) spectrum of the films was examined and showed the types of chemical bonds of the epoxy films before and after irradiation.

Effect of high irradiance and short exposure times on the depth of cure of six bulk-fill resin composites.

This study examined the effect of high irradiance and short exposure times on the depth of cure of six resin-based composites (RBCs). Bluephase PowerCure and the Valo X light-curing units (LCUs) were used to photocure bulk-fill RBCs for their recommended exposure times: Admira Fusion x-tra (AFX/20s), Aura Bulk Fill (ABF/20s), Filtek One Bulk Fill (FOB/20s), Opus Bulk Fill APS (OBF/30s), Tetric EvoCeram Bulk Fill (TEC/10s) and Tetric PowerFill (TPF/10s). In addition, all bulk-fill RBCs were tested for depth of cure with one short 3 s exposure time from the Bluephase PowerCure or the Valo X in the Xtra Power mode. The RBCs (n=10 per RBC) were inserted into a 4mm diameter metal mold and covered by a polyester strip before being photocured. After 24h of storage, uncured RBC was scraped away to determine the depth of cure of the RBCs. None of the RBCs achieved a 4mm depth of cure. The depth of cure of TEC and TPF was unaffected by the exposure times (recommended or short) when using the Valo X. The depth of cure of AFX/20s, AFX/Xtra Power, ABF/Xtra Power, FOB/Xtra Power, and OBF/30s RBCs was greater when using Valo X compared to the Bluephase PowerCure. It was concluded that short exposure times can reduce depth of cure and should only be used for some RBCs.

Base‐ and Visible‐Light‐Promoted Formation of 3‐Benzyl‐3‐Methoxyisoindolin‐1‐one

AbstractAryl diazonium salts are versatile compounds known for their reactivity in various transformations. In this study, we explored the arylation of 3‐methylene isoindolinones using aryl diazonium salts. The objective was to develop a method for accessing 3‐benzyl‐3‐methoxyisoindolin‐1‐ones, a class of compounds with diverse biological activities and synthetic importance. Optimization of the reaction conditions revealed the significance of light irradiation for improved yields. The substrate scope investigation demonstrated the compatibility of various diazonium salts and N‐substituents on the 3‐methylene isoindolinone scaffold, yielding the corresponding methoxy lactams with high yields. Mechanistic insights were obtained by observing the effect of base and light irradiation. Two initiation mechanisms were proposed: in the presence of a base, the reaction could proceed even without light irradiation, while light irradiation was necessary in the absence of a base. DFT calculations were performed to elucidate the mechanism of the reaction and provide energetic considerations