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We have been studying mesolytic cleavage of X−Y σ‐bond (X−Y=CH2−O, CH2−S, S−S and Se−Se) tethering aryl (Ar) moieties such as phenyl, biphenyl, α‐ and β‐naphthyl groups. In the present study, possibility of mesolytic cleavage of carbon‐carbon bonds in radical anions of diarylethanes (Ar1CCAr2) was investigated by pulsed electron radiolysis in N,N‐dimethylformamide (DMF) and 2‐methyltetrahydrofuran (MTHF). No mesolytic C−C bond cleavage in the radical anions occurred in both solvents whereas in MTHF, formation of H‐adducts of the diarylethanes was seen in the transient absorption spectral changes. Based on the DFT calculations for the bond dissociation energy of the C−C bond and the singly occupied molecular orbital distributions on Ar1CCAr2 radical anions, we rationalize the absence of the mesolysis in comparison with experimental facts previously reported for Ar1X‐YAr2 radical anions having X−Y σ‐bond. [ABSTRACT FROM AUTHOR]

This study conducts a comparative analysis of cystamine (RSSR), a disulfide, and cysteamine (RSH), its thiol monomer, to evaluate their efficacy as radioprotectors and antioxidants under high linear energy transfer (LET) and high-dose-rate irradiation conditions. It examines their interactions with reactive primary species produced during the radiolysis of the aqueous ferrous sulfate (Fricke) dosimeter, offering insights into the mechanisms of radioprotection and highlighting their potential to enhance the therapeutic index of radiation therapy, particularly in advanced techniques like FLASH radiotherapy. Using Monte Carlo multi-track chemical modeling to simulate the radiolytic oxidation of ferrous to ferric ions in Fricke-cystamine and Fricke-cysteamine solutions, this study assesses the radioprotective and antioxidant properties of these compounds across a variety of irradiation conditions. Concentrations were varied in both aerated (oxygen-rich) and deaerated (hypoxic) environments, simulating conditions akin to healthy tissue and tumors. Both cystamine and cysteamine demonstrate radioprotective and strong antioxidant properties. However, their effectiveness varies significantly depending on the concentration employed, the conditions of irradiation, and whether or not environmental oxygen is present. Specifically, excluding potential in vivo toxicity, cysteamine substantially reduces the adverse effects of ionizing radiation under aerated, low-LET conditions at concentrations above ~1 mM. However, its efficacy is minimal in hypoxic environments, irrespective of the concentration used. Conversely, cystamine consistently offers robust protective effects in both oxygen-rich and oxygen-poor conditions. The distinct protective capacities of cysteamine and cystamine underscore cysteamine's enhanced potential in radiotherapeutic settings aimed at safeguarding healthy tissues from radiation-induced damage while effectively targeting tumor tissues. This differential effectiveness emphasizes the need for personalized radioprotective strategies, tailored to the specific environmental conditions of the tissue involved. Implementing such approaches is crucial for optimizing therapeutic outcomes and minimizing collateral damage in cancer treatment. [ABSTRACT FROM AUTHOR]

Some of the issues concerning energy security and climate change can be addressed by employing nuclear power (NP) to supply the energy required for the conversion of carbon dioxide (CO2) into chemicals, products, and materials. Nuclear energy represents a neutral carbon source that can be generated sustainably, reliably, and consistently. Nuclear power plants (NPPs) could supply energy in the form of heat, electricity, and ionizing radiation to drive CO2 chemical reactions underpinning NP-to-X type of pathways. CO2 conversion processes are either commercially available or emerging technologies at different developmental maturity stages. This work reviews the published literature (articles and patents) that reports R&D results and the understanding and development of chemical reactions and processes, as well as the efforts in integrating NPPs and chemical processes (CPs). As will be made evident, a new industrial era for the manufacturing of decarbonized chemicals, products, and materials will be possible by developing and implementing new (more energy- and carbon-efficient) processes responding to the NP-to-X pathways. This new decarbonizing platform not only contributes to achieving net zero goals but also broadens the NPP product beyond electricity. [ABSTRACT FROM AUTHOR]

The influence of absorbed dose (up to 90 kGy) and the initial concentrations of ethylene glycol and glycerol (from 30 to 250 mg/L) on their degradation in aqueous solutions under a 3-MeV electron beam has been studied. Aeration of the solutions during irradiation decreased the yield of degradation. In the absence of aeration, the observed initial yields of degradation were about 0.23 µmol/J for ethylene glycol and about 0.14 µmol/J for glycerol. Degradation products formed in aqueous solutions are more resistant to ionizing radiation compared to the parent alcohols. A simultaneous reduction in alcohol concentration and chemical oxygen demand (COD) to standard values was achieved in solutions with an initial concentration of 30–40 mg/L at a dose of no higher than 2–3 kGy. [ABSTRACT FROM AUTHOR]

Formation kinetics of metal nanoparticles are generally described via mass transport and thermodynamics‐based models, such as diffusion‐limited growth and classical nucleation theory (CNT). However, metal monomers are commonly assumed as precursors, leaving the identity of molecular intermediates and their contribution to nanoparticle formation unclear. Herein, liquid phase transmission electron microscopy (LPTEM) and reaction kinetic modeling are utilized to establish the nucleation and growth mechanisms and discover molecular intermediates during silver nanoparticle formation. Quantitative LPTEM measurements show that their nucleation rate decreases while growth rate is nearly invariant with electron dose rate. Reaction kinetic simulations show that Ag4 and Ag− follow a statistically similar dose rate dependence as the experimentally determined growth rate. We show that experimental growth rates are consistent with diffusion‐limited growth via the attachment of these species to nanoparticles. The dose rate dependence of nucleation rate is inconsistent with CNT. A reaction‐limited nucleation mechanism is proposed and it is demonstrated that experimental nucleation kinetics are consistent with Ag42+ aggregation rates at millisecond time scales. Reaction throughput analysis of the kinetic simulations uncovered formation and decay pathways mediating intermediate concentrations. We demonstrate the power of quantitative LPTEM combined with kinetic modeling for establishing nanoparticle formation mechanisms and principal intermediates. [ABSTRACT FROM AUTHOR]

Manufacturing aqueous batteries based on the magnesium cations is an important step towards more sustainable and safer energy storage solutions. Thus, it is important to understand how these systems age and which species are formed throughout numerous charge/discharge cycles. To this end, we have used radiolysis to induce accelerated ageing in concentrated aqueous solutions of magnesium bistriflimide Mg(TFSI)2 (also called "water‐in‐salt electrolytes" or WISEs). We demonstrate in this work that the degradation products formed, whether in the gas or liquid phase, are very similar to those formed in concentrated LiTFSI aqueous solutions. In fact, the behavior under ionizing radiation is driven by the anion/water molar ratio regardless of whether the cation is Li+ or Mg2+. This is because both cations are non‐reactive, and the bond strengths in the TFSI− anion do not vary with the nature of the cation. Reaction mechanisms are proposed to explain the formation of several species under ionizing radiation. [ABSTRACT FROM AUTHOR]

Leydig cells are the primary source of testosterone or androgen production in male mammals. The blood–testis barrier (BTB) maintains structural integrity and safeguards germ cells from harmful substances by blocking their entry into the seminiferous tubules. L-cysteine is essential to the production of glutathione, a powerful antioxidant crucial to protecting against oxidative stress-induced damage. Animal studies have demonstrated the protective effect of L-cysteine in preventing testicular damage caused by chemicals or radiation. This study examines whether L-cysteine enhances the expression of testosterone biosynthesis and the BTB genes in human Leydig cells and THP-1 monocytes. The Leydig cells and THP-1 monocytes were treated with L-cysteine for 24 h. RNA was extracted following treatment, and the gene expression was analyzed using quantitative RT-PCR. Testosterone levels in the cell supernatant were measured using an ELISA kit. L-cysteine treatment in Leydig cells significantly upregulated the expression of CYP11A1 (p = 0.03) and the BTB genes CLDN1 (p = 0.03), CLDN11 (p = 0.02), and TJP1 (p = 0.02). Similarly, L-cysteine significantly upregulated the expression of CYP11A1 (p = 0.03) and CYP19A1 (p < 0.01), and the BTB genes CLDN1 (p = 0.04), CLDN2 (p < 0.01), CLDN4 (p < 0.01), CLDN11 (p < 0.01), and TJP1 (p = 0.03) in THP-1 monocytes. Further, L-cysteine supplementation increased the testosterone secretion levels in human Leydig cells. The findings suggest that L-cysteine supplementation could be used as an adjuvant therapy to promote the integrity of the BTB genes, testosterone biosynthesis and secretion, and the maintenance of testicular functions, which in turn mitigates the risk of male infertility. [ABSTRACT FROM AUTHOR]

MgKPO4·6H2O (magnesium potassium phosphate-based cement; MKP) is an environment friendly alternative to Portland cement with potential applications in environmental remediation and radioactive nuclear waste management, particularly in the context of β-emitting Cs and Sr immobilizations. Thus, investigation of the radiation effects and temperature due to decay heat in such material is of prime importance. In this study, MgKPO4·6H2O powders were synthesized and subsequently annealed at 1273 K for 2 h under ambient atmosphere to form MgKPO4. The synthesized and annealed MKP specimens were irradiated under ambient conditions with 10-MeV electron beam up to imparted doses of 20 MGy. XRD results reveal the formation of amorphous fraction in irradiated MgKPO4·6H2O, while the annealed MKP specimens exhibit good radiation stability without amorphization. The annealed specimens also indicated good thermal stability when compared to as-prepared MgKPO4·6H2O specimen both in pristine and irradiated conditions. Vibrational spectroscopic results confirm that the radiation effect resulted in distortion/removal of structural water and formation of radiolysis products in MgKPO4·6H2O. [ABSTRACT FROM AUTHOR]

Featured Application: The integration of supercritical water (SCW) technology in proposed Generation IV nuclear reactors marks a significant advancement in the evolution of nuclear energy. To achieve optimal water chemistry control and enhance reactor efficiency, safety, and sustainability, it is critical to thoroughly understand the radiation chemistry and behavior of transient species within the reactor core. This knowledge is particularly vital for the development of SCW-cooled reactor (SCWR) designs, including their SCW-cooled small modular reactor (SCW-SMR) variants. These reactors are designed to operate at temperatures between 300 and 600 °C and at a nominal pressure of 25 MPa. Our study focuses on the radiolysis of de-aerated, pure water by 2 MeV monoenergetic neutrons, mirroring the fast-neutron flux in a typical reactor setting. We provide a detailed analysis of the time-dependent chemical yields (G values) for both radical (e−aq, H●, and ●OH) and molecular (H2 and H2O2) primary species that are either formed or destroyed from 1 picosecond (ps) to 1 millisecond (ms). Given the unique operating conditions of SCWRs/SMRs, our findings are expected to be highly relevant and valuable to those working in the SCWR and SCW-SMR field. (1) Background: Supercritical water-cooled reactors (SCWRs) and their smaller modular variants (SMRs) are part of the 'Generation IV International Forum' (GIF) on advanced nuclear energy systems. These reactors operate beyond the critical point of water (tc = 373.95 °C and Pc = 22.06 MPa), which introduces specific technical challenges that need to be addressed. The primary concerns involve the effects of intense radiation fields—including fast neutrons, recoil protons/oxygen ions, and γ rays—on the chemistry of the coolant fluid and the integrity of construction materials. (2) Methods: This study employs Monte Carlo simulations of radiation track chemistry to investigate the yields of radiolytic species in SCWRs/SMRs exposed to 2 MeV neutrons. In our calculations, only the contributions from the first three recoil protons with initial energies of 1.264, 0.465, and 0.171 MeV were considered. Our analysis was conducted at both subcritical (300 and 350 °C) and supercritical temperatures (400–600 °C), maintaining a constant pressure of 25 MPa. (3) Results: Our simulations provide insights into the radiolytic formation of chemical species such as e−aq, H●, H2, ●OH, and H2O2 from ~1 ps to 1 ms. Compared to data from radiation with low linear energy transfer (LET), the G(e−aq) and G(●OH) values obtained for fast neutrons show a similar temporal dependence but with smaller amplitude—a result demonstrating the high LET nature of fast neutrons. A notable outcome of our simulations is the marked increase in G(●OH) and G(H2), coupled with a corresponding reduction in G(H●), observed during the homogeneous chemical stage of radiolysis. This evolution is attributed to the oxidation of water by the H● atom according to the reaction H● + H2O → ●OH + H2. This reaction acts as a significant source of H2, potentially reducing the need to add extra hydrogen to the reactor's coolant water to suppress the net radiolytic production of oxidizing species. Unlike in subcritical water, our simulations also indicate that G(H2O2) remains very low in low-density SCW throughout the interval from ~1 ps to 1 ms, suggesting that H2O2 is less likely to contribute to oxidative stress under these conditions. (4) Conclusions: The results of this study could significantly impact water-chemistry management in the proposed SCWRs and SCW-SMRs, which is crucial for assessing and mitigating the corrosion risks to reactor materials, especially for long-term operation. [ABSTRACT FROM AUTHOR]

The results of simulation of radiation-chemical transformations in the primary coolant of a water-cooled water-moderated energy reactor (VVER) are presented. It has been shown that under conditions of intense irradiation, molecular nitrogen dissolved in the coolant exhibits chemical activity. The reaction of N2 with the excited hydroxyl radical initiates the formation of ammonia and nitrous acid. Further decomposition of ammonia produces only oxidized forms of nitrogen, with N2 acting as an intermediate product. Maintaining hydrogen and oxygen concentrations within normal limits in the ammonia water chemistry is possible only with constant dosing of NH3 and degassing of the coolant. In the case of water chemistry with H2 dosing (at the initial moment), on the contrary, a stationary regime is quickly established in the absence of disturbances, satisfying the requirements of VVER water chemistry standards. The difference between the two water chemistry systems is due to the presence of nitrogen in the NH3 molecule and its transformations as an element, regardless of the initial chemical form. [ABSTRACT FROM AUTHOR]

The radiolysis of liquid and boiling hexafluoroacetylacetone has been studied. The structure of the main radiolysis products indicates the predominance of C–CF3 and C–F bond cleavages. Ten compounds including monoketones, trifluoroacetic acid, keto alcohols, and tautomeric tetraketones were formed. Carbon monoxide was the main gaseous product, and its yield increased under boiling conditions. The initial yields of hexafluoroacetylacetone degradation were 0.29 ± 0.2 and 0.32 ± 0.2 µmol/J at 293 and 343 K, respectively. No accumulation of free HF was observed at low doses. The products of radiolysis are less diverse than those in acetylacetone; this is due to enhancement of the cage effect and to an increase the Onsager radius and the ability of trifluoromethyl groups to dissipate excitation energy. [ABSTRACT FROM AUTHOR]

The article discusses the potential problems that have to be solved in the framework of development and justification of the water chemistry (WC) conditions required to ensure corrosion resistance of the structural materials used in the core and coolant circuit of the power-generating reactor used in the supercritical water cooled VVER-SCW nuclear power plant (NPP). In reactors cooled with water at supercritical temperature and pressure, the integrity of their physical barriers (fuel-rod claddings and reactor coolant circuit boundaries) depends in many respects on the possibility of maintaining the necessary water chemistry conditions that will guarantee the corrosion resistance of equipment and pipeline structural materials for the power unit's entire service life. The most complex challenge in this regard is to inhibit corrosion and flow-accelerated corrosion processes and to minimize the formation of deposits on the surface of equipment operating in the domain of near-critical and supercritical conditions. The article formulates the limitations that are suggested to be considered in transferring the experience gained from the standardization of water chemistry in supercritical pressure (SCP) power units at thermal and nuclear power plants to the VVER-SCW NPPs. An analysis is carried out that makes it possible to estimate the effect the chemical composition of a supercritical water coolant has on the corrosion state of candidate structural materials for fuel-rod claddings with the aim to get better insight in the main processes occurring in aqueous solutions and for developing (elaborating) a WC conduction technology as applied to ensuring the integrity of the VVER-SCW NPP physical safety barriers. [ABSTRACT FROM AUTHOR]

This paper presents the results of the research on the effects of ionizing radiation on the properties of a composite material consisting of polypropylene (PP) and hemp fibers (HFs). The radiolysis effects were investigated for the composites having HF contents in the amounts of 10, 20, 30, and 40% by weight, as well as for pure PP. Particular attention was paid to the protective effects the aromatic compounds contained in the HF had on the radiolysis of PP/HF composites. This phenomenon may explain the deviations that the irradiated composites displayed upon the addition of HFs and their dependency on the HF content. Both the granules and the standardized composite specimens were subjected to radiation treatment. The gas chromatography (GC) technique was employed to determine the yield of radiolytically generated hydrogen (GH2) and absorbed oxygen (GO2). The oxidation phenomenon was studied during irradiation, 24 h after irradiation, and after a 40-day aging period at room temperature. Changes in the melt flow rate (MFR) and the mechanical properties were also determined. It was described how the radiation treatment of the investigated composites accelerates their degradation. It was found that this effect applies to both HF and PP. It was also demonstrated that PP not only does not enhance the resistance of HF to oxidation but, on the contrary, accelerates the processes of their post-radiation degradation. It was further observed that the phenomenon of postradiation degradation can be controlled by changing the PP content in the composite, as well as the amount of aromatic compounds present in the HF. The amount of the absorbed dose allows us to control the degradation time of the PP/HF composites. This applies in particular to the chain oxidation of the PP matrix triggered by the ionizing radiation. It was also found that composites based on PP and natural fibers susceptible to radiation degradation may have significant implications for the use of easily degradable polymer materials in the environment.

(1) Background: In the quest to accurately model the radiolysis of water in its supercritical state, a detailed understanding of water's molecular structure, particularly how water molecules are arranged in this unique state, is essential. (2) Methods: We conducted molecular dynamics simulations using the SPC/E water model to investigate the molecular structures of supercritical water (SCW) over a wide temperature range, extending up to 800 °C. (3) Results: Our results show that at a constant pressure of 25 MPa, the average intermolecular distance around a reference water molecule remains remarkably stable at ~2.9 Å. This uniformity persists across a substantial temperature range, demonstrating the unique heterogeneous nature of SCW under these extreme conditions. Notably, the simulations also reveal intricate patterns within SCW, indicating the simultaneous presence of regions with high and low density. As temperatures increase, we observe a rise in the formation of molecular clusters, which are accompanied by a reduction in their average size. (4) Conclusions: These findings highlight the necessity of incorporating the molecular complexity of SCW into traditional track-structure chemistry models to improve predictions of SCW behavior under ionizing radiation. The study establishes a foundational reference for further exploration of the properties of supercritical water, particularly for its application in advanced nuclear technologies, including the next generation of water-cooled reactors and their small modular reactor variants that utilize SCW as a coolant. [ABSTRACT FROM AUTHOR]

Perchlorates have been found in the regolith of Mars and the Moon, in the ice of Europa, and in meteorites. Studying the processes of formation and destruction of these compounds is important both for understanding the geological and climatic evolution of a number of planets and bodies of the Solar System, and for assessing their habitability. To date, a number of processes for the synthesis of perchlorates under Martian conditions have been proposed, but these do not explain the perchlorate concentrations observed in the regolith and are not applicable to atmosphereless bodies, in particular Europa. We have studied the processes of synthesis and destruction of perchlorates during irradiation of ice and regolith models with high-energy electrons under conditions of low temperature (–50°C) and in the absence of an atmosphere (at a pressure of 0.01 mbar). The data obtained indicate that perchlorates can be efficiently synthesized in the regolith of Mars and the surface layer of Europa ice under the influence of irradiation in the absence of a liquid phase or an atmosphere. [ABSTRACT FROM AUTHOR]

The constituent parts of systems where radiation-catalytic processes occur usually differ in terms of mass and electron density, structural characteristics, electro-physical and chemical properties. Therefore, interaction between phases in any form has a sharp effect on the direction and parameters of the processes in individual components. The resulting X-ray diffraction pattern was mainly determined by the atomic plane (ε), the intensity of the obtained peaks, the corresponding syngony of the sample, the lattice size, density, lattice constants, and the distance between the phase groups. The X-ray diffraction data were processed using the Full prof program. Full-profile processing of NaNO3 X-ray diffraction data showed that the initial sample has a triclinic structure. The scientific component of the article is of interest be- cause it touches upon the issues of structural transformations of NaNO3 under the action of gamma radiation. The radiation- heterogeneous processes of water decomposition NaNO3 have been studied. The kinetics of buildup of molecular hydrogen in the radiolysis processes of water decomposition has been examined. Hydrogen generation by water splitting is reported in NaNO3 + H2Oabs., NaNO3 + H2Oflu. systems using gamma radiation and 300 K temperature. This indicates that in the case of finding NaNO3 in the volume of water, there is an effective transfer of energy from the solid phase to water molecules. The presence of the second slow stage of radiolysis on the kinetic curves indicates that there is a diffusion-hindered stage of heterogeneous radiolysis of water in the presence of nanoparticles at 300 K. [ABSTRACT FROM AUTHOR]

Radiolysis of α-pinene by 61.3 MeV 84Kr15 + ions was analysed with the scope to simulate the effects of heavy ion cosmic ray bombardment on chiral molecules in the interstellar medium. The α-pinene ice samples were irradiated at 10 K and their chemical evolution was monitored by mid-infrared Fourier transform (FTIR) spectroscopy to characterize the reaction products and to determine the extent of racemization. The integrated band strengths have been obtained for all the neutral α-pinene vibrational bands using the experimental band integrated absorbances and the theoretical absolute intensities calculated along the column densities. In the current heavy ion bombardment experiments, small molecules were formed and the precursor, α-pinene, was destroyed instead of being racemized. Twelve hydrocarbons were produced (final fluence of 2.0 × 1012 ions cm−2): methane (CH4), acetylene (C2H2), ethylene (C2H4), propylene (C3H6), propane (C3H8), n-butane (C4H10), butene (C4H8), propyne (C3H4), benzene (C6H6), ethane (C2H6), vinylacetylene (C4H4), and 2-methyl-1,3-butadiene or isoprene (C5H8). The highest formation cross-section (∼ 40 × 10−15 cm2) was observed for the C3H4 and the lowest was for C3H8 (∼ 3 × 10−15 cm2). The radiochemical yields for these molecules follow the same trends as those of their cross-sections. The atom budget calculation confirms that all the expected products have been generated during the radiolysis and supports the conclusion that the proposed A values are accurate. The α-pinene sputtering yield for this ion beam was found to be Y0  = 1.84 × 106 molecules per impact. [ABSTRACT FROM AUTHOR]

It is generally accepted that radiolysis of water on the surface of PuO2 by alpha particles is the source of H2 which can cause pressurisation in sealed storage containers if the material is not adequately conditioned before packing. The mechanisms for this have not been discussed in detail previously. Radiolysis mechanisms of bulk water are summarised and then applied to water at the surface of PuO2. It is shown that the radiolysis processes occurring on timescales of less than 1 ps after energy deposition could have an impact on the storage behaviour of the PuO2 and the potential gas volume generated. Some of the radiolysis products are highly reactive and would be expected to react with plutonium at the surface, affecting the usual water radiolysis processes. A corollary of this observation is that the surface should not be considered a completely crystalline PuO2 solid. It is also highlighted that whilst there are significant uncertainties in the radiolysis process at the PuO2 surface there are also significant uncertainties in H2 formation mechanisms in bulk water. Finally, methods to model the radiolysis process at the surface and the prospects for predictive models are briefly discussed with suggestions for future areas of development. [ABSTRACT FROM AUTHOR]

Formation kinetics of metal nanoparticles are generally described via mass transport and thermodynamics‐based models, such as diffusion‐limited growth and classical nucleation theory (CNT). However, metal monomers are commonly assumed as precursors, leaving the identity of molecular intermediates and their contribution to nanoparticle formation unclear. Herein, liquid phase transmission electron microscopy (LPTEM) and reaction kinetic modeling are utilized to establish the nucleation and growth mechanisms and discover molecular intermediates during silver nanoparticle formation. Quantitative LPTEM measurements show that their nucleation rate decreases while growth rate is nearly invariant with electron dose rate. Reaction kinetic simulations show that Ag4 and Ag− follow a statistically similar dose rate dependence as the experimentally determined growth rate. We show that experimental growth rates are consistent with diffusion‐limited growth via the attachment of these species to nanoparticles. The dose rate dependence of nucleation rate is inconsistent with CNT. A reaction‐limited nucleation mechanism is proposed and it is demonstrated that experimental nucleation kinetics are consistent with Ag42+ aggregation rates at millisecond time scales. Reaction throughput analysis of the kinetic simulations uncovered formation and decay pathways mediating intermediate concentrations. We demonstrate the power of quantitative LPTEM combined with kinetic modeling for establishing nanoparticle formation mechanisms and principal intermediates.

In the study, the optimal values of the ratio of the distance between particles to the particle size in the radiation-heterogeneous radiolysis of water in nano-Me and nano-MeO systems were determined. In those systems, the effect of water density and system temperature on the radiation-chemical release of molecular hydrogen obtained from thermal and radiation-thermal decomposition of water was considered. The article also determined the effect of particle sizes and the type of sample taken on the radiation chemical yield of molecular hydrogen. In the presented article, the change of molecular hydrogen according to adsorbed water and catalyst was studied. Thus, in the case of a suspension of nano-zirconium in water, the energy of electrons emitted from the metal is completely transferred to water molecules, which leads to an increase in the yield of hydrogen. When radiolysis of water in the presence of nano-metals, energy transfer can be carried out mainly with the participation of emitted electrons. Therefore, in the case of radiolysis of water in suspension with n-Zr, the yield of hydrogen increases by 5.4 times compared to the processes of radiolysis in an adsorbed state. However, in radiation-heterogeneous processes of obtaining hydrogen from water in contact with metal systems, it is necessary to take into account that as a result of these processes surface oxidation occurs and after a certain time the systems are converted to n-Me-MeO+H2Oliq. systems. For nano sized oxide compounds, the mean free path of secondary electrons formed as a result of primary processes of interaction of quanta with atoms is commensurate with the particle sizes of nano-oxides (λ ≈ R_(H-оxides)). Further, these electrons interact with the electronic subsystem of silicon. For nanocatalysts, the length of free paths of secondary and subsequent generations of electrons is greater than the size of catalyst particles (R_cat≤100nm). Usually, their energy is sufficient to conduct independent radiolytic processes in the contact medium of the catalyst.

A systematic study of the impact on the chemical reactivity of the oxidising n-dodecane radical cation (RH˙+) with f-element complexed 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) has been undertaken utilizing time-resolved electron pulse radiolysis/transient absorption spectroscopy and high-level quantum mechanical calculations. Lanthanide ion complexed species, [Ln((HEH[EHP])2)3], exhibited vastly increased reactivity (over 10× faster) in comparison to the non-complexed ligand in n-dodecane solvent, whose rate coefficient was k = (4.66 ± 0.22) × 109 M−1 s−1. Similar reactivity enhancement was also observed for the corresponding americium ion complex, k = (5.58 ± 0.30) × 1010 M−1 s−1. The vastly increased reactivity of these f-element complexes was not due to simple increased diffusion-control of these reactions; rather, enhanced hole transfer mechanisms for the complexes were calculated to become energetically more favourable. Interestingly, the observed reactivity trend with lanthanide ion size was not linear; instead, the rate coefficients showed an initial increase (Lu to Yb) followed by a decrease (Tm to Ho), followed by another increase (Dy to La). This behaviour was excellently predicted by the calculated reaction volumes of these complexes. Complementary cobalt-60 gamma irradiations for select lanthanide complexes demonstrated that the measured kinetic differences translated to increased ligand degradation at steady-state timescales, affording ∼38% increase in ligand loss of a 1 : 1 [La((HEH[EHP])2)3] : HEH[EHP] ratio system. [ABSTRACT FROM AUTHOR]

While particle therapy has been used for decades for cancer treatment, there is still a lack of information on the molecular mechanisms of biomolecules radiolysis by accelerated ions. Here, we examine the effects of accelerated protons on highly concentrated native myoglobin, by means of Fourier transform infrared and UV–Visible spectroscopies. Upon irradiation, the secondary structure of the protein is drastically modified, from mostly alpha helices conformation to mostly beta elements at highest fluence. These changes are accompanied by significant production of carbon monoxide, which was shown to come from heme degradation under irradiation. The radiolytic yields of formation of denatured protein, carbon monoxide, and of heme degradation were determined, and found very close to each other: G+denatured Mb ≈ G+CO ≈ G-heme = 1.6 × 10–8 ± 0.1 × 10–8 mol/J = 0.16 ± 0.01 species/100 eV. The denaturation of the protein to a beta structure and the production of carbon monoxide under ion irradiation are phenomena that may play an important role in the biological effects of ionizing radiation. [ABSTRACT FROM AUTHOR]

1,1,7-Trihydrododecafluoroheptanol is a promising solvent for the development of strontium-selective extractants based on individual stereoisomers of dicyclohexano-18-crown-6 (DCH18C6). In this study the distribution of DCH18C6 between organic and aqueous phases was determined and the effect of macrocycle stereoisomerism was revealed. Extractability of nitric acid depended on the acidity of initial aqueous phase and did not on DCH18C6 stereoisomerism. Based on the structure of radiolytic intermediates, the main channels of radiation destruction of the macrocycle and the solvent were proposed. The obtained data highlights the potentiality of the DCH18C6/1,1,7-trihydrododecafluoroheptanol for designing a technological process for the selective strontium extraction. [ABSTRACT FROM AUTHOR]

The radiolysis of malondialdehyde (MDA) in acidic (pH 3) and alkaline (pH 11) aqueous solutions has been studied using UV spectrometry, HPLC, and chemical analysis. It has been found that in an acidic medium, the radiation-chemical yield of degradation of MDA at concentrations greater than 3 × 10–4 mol/L exceeds 10 molecule/100 eV, indicating the occurrence of chain processes. It has been established that dissolved oxygen plays an important role in the chain process of MDA decomposition. A system of reactions was proposed to explain the results of the experiments. [ABSTRACT FROM AUTHOR]

The influence of scavengers of the primary water radiolysis products and the H atom on the spectra and intensity of radioluminescence and photoluminescence of the Tb3+ ion in aqueous solutions of TbCl3 and Tb(NO3)3 is considered. The effect of activation of Tb3+ radioluminescence in the presence of H scavengers has been revealed, indicating the presence of a specific (Tb3+)* quenching reaction by this radiolysis product, which is inhibited by its scavengers. Enhancement in the activation has been revealed in the joint presence of H and scavengers in the solution, with a similar effect of activation of Tb3+ radioluminescence being previously established for scavengers. [ABSTRACT FROM AUTHOR]

A major subject for evaluating the corrosive conditions in the pressurized water reactor (PWR) primary coolant is to determine the optimal hydrogen concentration for mitigating primary water stress corrosion cracking (PWSCC) without adverse effects on major structural materials. An analytical method combining water radiolysis and electrochemical corrosion potential (ECP) analyses was proposed for evaluating the corrosive conditions in PWR primary coolant. These procedures originally developed for boiling water reactors (BWRs) were successfully extended to PWRs with different water chemistry parameters, including pH, temperature, and radiation qualities, after minor changes in the original procedures and major input parameters, such as the inclusion of the effects of alpha radiolysis and Li+ (Na+) and H+ effects for the anodic polarization curve. This study discusses the results of water radiolysis analysis for PWR primary coolant, and the characteristic behavior of hydrogen peroxide (H2O2) as a function of hydrogen inlet concentrations in PWR primary coolant conditions (higher pH and α-ray irradiation). A possible reaction scheme involving eaq– was proposed for H2O2 suppression under alkaline conditions. The corrosive conditions were discussed in the following publication, using ECP as the major index for PWR corrosive conditions. [ABSTRACT FROM AUTHOR]

Hydrogen (H2) is among the most common and widely utilized electron donors in microbial metabolism. This is particularly true for microorganisms that inhabit subsurface environments where H2 concentrations can be high due to H2 generation via one or more abiotic and biotic processes, such as serpentinization, radiolysis, cataclasis, and microbial fermentation. A surge in interest in the exploration for and exploitation of geologic (i.e., white and orange) H2 as a clean low carbon fuel therefore necessitates an evaluation of the influence of microorganisms on its flux and potential recovery from subsurface systems. The widespread application of high throughput metagenomic sequencing approaches to rock-hosted ecosystems now makes it possible to readily identify microorganisms that harbor the potential to metabolize H2 and to predict their mode of coupling H2 oxidation with available oxidants using comparative genomic data from natural samples alone. When combined with several recent reports of measured rates of net microbial H2 consumption in rock-hosted ecosystems, such information provides new perspective on the potential for microorganisms to impact the economics of H2 recovery from geologic systems. In this perspective, the different classes of enzymes that microorganisms use to reversibly oxidize H2 to fuel their energy metabolism are introduced and their distribution in several rock-hosted ecosystems is discussed. A compilation of net microbial H2 oxidation activities in rockhosted ecosystems is also presented to enable estimates of potential H2 loss from natural or stimulated geologic reservoirs during mining activities, with an example provided from the Samail Ophiolite that indicates >90% of geologic H2 produced could be lost to microbial consumption. Finally, avenues to guide future microbial research in environments where geologic H2 mining is planned are discussed. [ABSTRACT FROM AUTHOR]

Dihydroxyurea (DHU) is a novel salt-free reductant used in the reprocessing of spent fuel. This paper reports on the radiolysis of DHU in water and its radiolytic products. The concentration reduction ratio of DHU after irradiation increases with the dose but decreases with increasing DHU concentration. The radiolytic by-products are H2, CO2 NH4+ and HNO2. The amount of H2, CO2 and NH4+ increases with DHU concentration, but that of HNO2 decreases with increasing DHU concentration. The quantity of CO2 and NH4+ increases with the dose. The radiation chemical yields of DHU destruction and radiolytic products are determined. [ABSTRACT FROM AUTHOR]

A review of data on sources and sinks of hydrogen of various origins in the atmosphere and in the near-surface part of the earth's crust is given (in some cases we are talking about the crust as a whole). Based on the results of the consideration of this information, it was concluded that the influence of underground non-biogenic ("geological, (white)") hydrogen on the content and balance of gas in the atmosphere, up to the stratosphere, is insignificant. The complexity of the experimental determination of the flow of geological hydrogen, free of biogenic and anthropogenic interference, the influence of the testable excavation, etc. is obvious. Probable sources of deep hydrogen are considered: the remains of magmatic gases (outside the areas of volcanism), metamorphic reactions, and radiolysis of water. The possibility of significant H2 export is evident only in currently activated fault zones. The data on the most powerful suppliers of geological hydrogen - modern active volcanoes and thermal fields - are given. The gas circulation scheme of the Avacha volcano is built, based on the thermal model. The latter is controlled by data from geothermometers, the results of direct temperature measurements in deep wells, and a velocity model. The possibility of fumaroles carrying unchanged hydrogen from the magma chamber has been shown. The prospects for the formation of hydrogen deposits are assessed as uncertain. Magmatic and metamorphogenic gas in some areas is formed enough to accumulate a significant deposit over several tens of thousands of years. But the possibility of its preservation during this period or longer raises doubts. Hydrocarbon deposits without material input from great depths can lose reserves in much less time. Higher rocks' permeability to hydrogen contributes to much greater gas leaks. [ABSTRACT FROM AUTHOR]

Copper nanoparticles (CuNPs) have drawn considerable interest because of recent evidences on greater Surface Enhanced Raman Spectroscopic (SERS) signal enhancing capability, high antibacterial activity and strong catalytic property with regard to the long existing popular silver and gold particles. The existing chemical synthesis methods usually require extensive purification to remove unreacted inorganic reducing agents, like sodium borohydride used to convert Cu2+ ions to Cu0 and it limits direct use of as-prepared materials in biologic systems. Here, we have endeavored to synthesize starch encapsulated CuNPs through radiation chemical approach which is considered to be one of the cleanest routes and involve in-situ generated hydrated electrons to reduce metal ions directly. Presence of large number of hydroxyl groups within starch molecules facilitates complexation of Cu(II) and thereby stabilizes CuNPs. Transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) illustrate that particles synthesized at a typical dose of 83.6 kGy are spherical with size of ca. 8 nm having polycrystalline face-centered cubic phase. The observed blue shift of the absorption maximum suggests formation of smaller sized particles with increase in applied radiation dose keeping other parameters same and this is supported by dynamic light scattering (DLS) data. Further, catalytic efficiency of as-synthesized CuNPs was tested by monitoring sodium borohydride mediated catalytic reduction of para-nitrophenol to para-aminophenol and the apparent rate constant (kapp) was estimated as 3 × 10–3 s−1. Thus, as-synthesized CuNPs appears to be better catalyst than the copper nanoparticles synthesized through conventional method for having kapp of about 1.6 × 10–3 s−1. [ABSTRACT FROM AUTHOR]

In this study, we explored the impacts of radiation damage and chemical composition on the etching time of monazite fission-track (MFT). Despite the potential of MFT as an ultra-low-temperature thermochronology, the comprehensive effects of radiation damage and non-formula elements, especially on the etching rate of MFT, remain unexplored, and established analytical procedures are lacking. We quantified the degree of radiation damage (ΔFHWM) of Cretaceous to Quaternary monazites distributed in the Japan arc through Raman spectroscopy and chemical composition analyses. Subsequently, MFT etching was performed to examine the correlation between these parameters and the etching time. Estimation of the degree of radiation damage showed an increase in radiation damage corresponding to the cooling age of each geological unit. For example, Monazites from Quaternary geological units, the Toya ignimbrite (ca. 0.1 Ma) and the Kurobegawa granodiorite (ca. 0.8 Ma), have ΔFHWM of 0.48 and 0.70 cm-1, respectively. In contrast, the Muro ignimbrite (ca. 15 Ma) has a ΔFHWM of 4.11 cm⁻¹, while Cretaceous granitoids, including the Kibe granite and the Sagawa granite, yielded 7.42 and 6.40 cm⁻¹, respectively. MFT etching of these samples according to the existing recipe (6M HCl at 90 °C for 60–90 minutes) was completed at 1200, 860, 210, 120, and 90 minutes for Toya ignimbrite, Kurobegawa granodiorite, Muro ignimbrite, Sagawa granite, and Kibe granite respectively. These outcomes highlight an inverse relationship between MFT etching time and the degree of radiation damage in monazite, while the correlation between MFT etching time and chemical composition was unclear. The results affirm earlier considerations that the etching rate of MFT is strongly influenced by radiation damage. Conversely, young samples with lower levels of radiation damage exhibit higher chemical resistance, suggesting that existing etching recipes may not adequately etch MFT. [ABSTRACT FROM AUTHOR]

Background: In the past years, there has been a notable increase in interest regarding targeted alpha therapy using Ac-225, driven by the observed promising clinical anti-tumor effects. As the production and technology has advanced, the availability of Ac-225 is expected to increase in the near future, making the treatment available to patients worldwide. Main body: Ac-225 can be labelled to different biological vectors, whereby the success of developing a radiopharmaceutical depends heavily on the labelling conditions, purity of the radionuclide source, chelator, and type of quenchers used to avoid radiolysis. Multiple (methodological) challenges need to be overcome when working with Ac-225; as alpha-emission detection is time consuming and highly geometry dependent, a gamma co-emission is used, but has to be in equilibrium with the mother-nuclide. Because of the high impact of alpha emitters in vivo it is highly recommended to cross-calibrate the Ac-225 measurements for used quality control (QC) techniques (radio-TLC, HPLC, HP-Ge detector, and gamma counter). More strict health physics regulations apply, as Ac-225 has a high toxicity, thereby limiting practical handling and quantities used for QC analysis. Conclusion: This overview focuses specifically on the practical and methodological challenges when working with Ac-225 labelled radiopharmaceuticals, and underlines the required infrastructure and (detection) methods for the (pre-)clinical application. [ABSTRACT FROM AUTHOR]

The effect of gamma radiation on olefins was studied under static conditions at an absorbed dose of 65 kGy and at a dose rate of P = 0.076 Gy/s. The effect of radiation on the physicochemical characteristics and structural and group composition of the resulting olefins has been established. Post-radiation effects were studied immediately after irradiation and during 1, 2, 4, and 7 months later. When fuels are irradiated, polymerization of unsaturated hydrocarbons occurs. After the irradiation cessation, there occurs postpolymerization process. The chemical instability of olefins in fuels leads to the formation of carbon deposits in the engine system, tanks, and valves. IR spectra, iodine values, density, and kinematic viscosity of irradiated samples were measured. [ABSTRACT FROM AUTHOR]

This article, titled "Editorial: Plutonium legacy storage and degradation," discusses the safe and secure management of plutonium, a special nuclear material (SNM) that is used in nuclear weapons and can also be used as a fuel for power generation. The article highlights the challenges associated with the storage of separated, unirradiated plutonium, including radiological hazards, proliferation risks, and physical security. It also explores the chemical hazards that can arise from processes such as radiolysis and radioactive decay. The article presents research papers that address the issues of radiolysis, long-term storage, and the conversion of plutonium oxalate to oxide. The goal of this research is to enhance the understanding and management of plutonium for the sake of safety and security. [Extracted from the article]

Introduction. The use of radiopharmaceuticals for targeted radionuclide therapy (TRT), the efficacy of which was established during clinical trials, is safe and effective for various pathological conditions, including cancer. The main feature of therapeutic radiopharmaceuticals (RPs) is the use of β–- and α-emitting radionuclides (RNs) in the finished dosage form (FD). Among the radionuclides used for radionuclide therapy, lutetium-177 is currently one of the most popular in clinical practice because of its chemical and nuclear characteristics. The list of RPs based on lutetium-177 is constantly expanding, and Lutathera® ([177Lu]Lu-DOTA-TATE) and Pluvicto™ ([177Lu]Lu-PSMA-617) have been approved for clinical use in several countries.Text. Because of the high activity of RNs in a single dose of therapeutic RPs (up to 8 GBq in a monodose for 177Lu), ionizing radiation of the used RNs leads to a decrease in RPs quality owing to radiolytic degradation of the vector molecule. This leads to a decreased specific accumulation of radioactivity in the foci of pathology, reduced therapeutic effect, and potentially increases the risk of radiotoxicity to non-target organs and tissues. The degree and intensity of radiolytic degradation of the vector molecule and, consequently, the shelf life of RPs depend on many factors, among which the activity concentration of the radionuclide in the preparation, its half-life, and the energy of the emitted particles are the most important. To suppress the effects of radiolysis, various excipients with antioxidant (radioprotective) properties were introduced into the compositions of the finished dosage forms. Among the substances studied, the most popular were gentisic acid, ascorbic acid, and ethanol. In this work, the advantages and disadvantages of various antioxidants and their combinations used in therapeutic RPs were considered in lutetium-177 preparations.Conclusion. Selection of the optimal composition of the dosage form is an urgent task, as it will ensure high-quality RPs both at the time of preparation and during the shelf life and delivery to the end user, which will greatly facilitate the use and centralized supply of therapeutic RPs. The necessity of creating a unified approach for the selection of antioxidants at the pharmaceutical development stage of radiopharmaceuticals is shown. For this purpose, an approach combining studies of radical reaction kinetics with studies of radiation-chemical yields of radiolysis products under identical or maximally similar conditions with subsequent verification of the stability of RPs dosage form seems to be very promising and has proven to be effective. In contrast, the empirical approach, which implies the selection of radioprotectors based on a direct study of their influence on the preservation of the level of radiochemical purity, is suboptimal because of the high market value of both radionuclides and non-radioactive precursors.

Some of the issues concerning energy security and climate change can be addressed by employing nuclear power (NP) to supply the energy required for the conversion of carbon dioxide (CO2) into chemicals, products, and materials. Nuclear energy represents a neutral carbon source that can be generated sustainably, reliably, and consistently. Nuclear power plants (NPPs) could supply energy in the form of heat, electricity, and ionizing radiation to drive CO2 chemical reactions underpinning NP-to-X type of pathways. CO2 conversion processes are either commercially available or emerging technologies at different developmental maturity stages. This work reviews the published literature (articles and patents) that reports R&D results and the understanding and development of chemical reactions and processes, as well as the efforts in integrating NPPs and chemical processes (CPs). As will be made evident, a new industrial era for the manufacturing of decarbonized chemicals, products, and materials will be possible by developing and implementing new (more energy- and carbon-efficient) processes responding to the NP-to-X pathways. This new decarbonizing platform not only contributes to achieving net zero goals but also broadens the NPP product beyond electricity.

This study conducts a comparative analysis of cystamine (RSSR), a disulfide, and cysteamine (RSH), its thiol monomer, to evaluate their efficacy as radioprotectors and antioxidants under high linear energy transfer (LET) and high-dose-rate irradiation conditions. It examines their interactions with reactive primary species produced during the radiolysis of the aqueous ferrous sulfate (Fricke) dosimeter, offering insights into the mechanisms of radioprotection and highlighting their potential to enhance the therapeutic index of radiation therapy, particularly in advanced techniques like FLASH radiotherapy. Using Monte Carlo multi-track chemical modeling to simulate the radiolytic oxidation of ferrous to ferric ions in Fricke-cystamine and Fricke-cysteamine solutions, this study assesses the radioprotective and antioxidant properties of these compounds across a variety of irradiation conditions. Concentrations were varied in both aerated (oxygen-rich) and deaerated (hypoxic) environments, simulating conditions akin to healthy tissue and tumors. Both cystamine and cysteamine demonstrate radioprotective and strong antioxidant properties. However, their effectiveness varies significantly depending on the concentration employed, the conditions of irradiation, and whether or not environmental oxygen is present. Specifically, excluding potential in vivo toxicity, cysteamine substantially reduces the adverse effects of ionizing radiation under aerated, low-LET conditions at concentrations above ~1 mM. However, its efficacy is minimal in hypoxic environments, irrespective of the concentration used. Conversely, cystamine consistently offers robust protective effects in both oxygen-rich and oxygen-poor conditions. The distinct protective capacities of cysteamine and cystamine underscore cysteamine’s enhanced potential in radiotherapeutic settings aimed at safeguarding healthy tissues from radiation-induced damage while effectively targeting tumor tissues. This differential effectiveness emphasizes the need for personalized radioprotective strategies, tailored to the specific environmental conditions of the tissue involved. Implementing such approaches is crucial for optimizing therapeutic outcomes and minimizing collateral damage in cancer treatment.

(1) Background: Supercritical water-cooled reactors (SCWRs) and their smaller modular variants (SMRs) are part of the ‘Generation IV International Forum’ (GIF) on advanced nuclear energy systems. These reactors operate beyond the critical point of water (tc = 373.95 °C and Pc = 22.06 MPa), which introduces specific technical challenges that need to be addressed. The primary concerns involve the effects of intense radiation fields—including fast neutrons, recoil protons/oxygen ions, and γ rays—on the chemistry of the coolant fluid and the integrity of construction materials. (2) Methods: This study employs Monte Carlo simulations of radiation track chemistry to investigate the yields of radiolytic species in SCWRs/SMRs exposed to 2 MeV neutrons. In our calculations, only the contributions from the first three recoil protons with initial energies of 1.264, 0.465, and 0.171 MeV were considered. Our analysis was conducted at both subcritical (300 and 350 °C) and supercritical temperatures (400–600 °C), maintaining a constant pressure of 25 MPa. (3) Results: Our simulations provide insights into the radiolytic formation of chemical species such as e−aq, H●, H2, ●OH, and H2O2 from ~1 ps to 1 ms. Compared to data from radiation with low linear energy transfer (LET), the G(e−aq) and G(●OH) values obtained for fast neutrons show a similar temporal dependence but with smaller amplitude—a result demonstrating the high LET nature of fast neutrons. A notable outcome of our simulations is the marked increase in G(●OH) and G(H2), coupled with a corresponding reduction in G(H●), observed during the homogeneous chemical stage of radiolysis. This evolution is attributed to the oxidation of water by the H● atom according to the reaction H● + H2O → ●OH + H2. This reaction acts as a significant source of H2, potentially reducing the need to add extra hydrogen to the reactor’s coolant water to suppress the net radiolytic production of oxidizing species. Unlike in subcritical water, our simulations also indicate that G(H2O2) remains very low in low-density SCW throughout the interval from ~1 ps to 1 ms, suggesting that H2O2 is less likely to contribute to oxidative stress under these conditions. (4) Conclusions: The results of this study could significantly impact water-chemistry management in the proposed SCWRs and SCW-SMRs, which is crucial for assessing and mitigating the corrosion risks to reactor materials, especially for long-term operation.

This paper reviews the radiation-induced synthesis of metallic nanostructures and their applications. Radiolysis is a powerful method for synthesizing metallic nanoparticles in solution and heterogeneous media, and it is a clean alternative to other existing physical, chemical, and physicochemical methods. By varying parameters such as the absorbed dose, dose rate, concentrations of metallic precursors, and nature of stabilizing agents, it is possible to control the size, shape, and morphology (alloy, core-shell, etc.) of the nanostructures and, consequently, their properties. Therefore, the as-synthesized nanoparticles have many potential applications in biology, medicine, (photo)catalysis, or energy conversion. [ABSTRACT FROM AUTHOR]

A representative naturally occurring coumarin, 4-methylumbelliferone (5), was exposed to 50 kGy of gamma ray, resulting in four newly generated dihydrocoumarin products 1–4 induced by the gamma irradiation. The structures of these new products were elucidated by interpretation of spectroscopic data (NMR, MS, [α]D, and UV). The unusual bisdihydrocoumarin 4 exhibited improved tyrosinase inhibitory capacity toward mushroom tyrosinase with IC50 values of 19.8 ± 0.5 μM as compared to the original 4-methylumbelliferone (5). A kinetic analysis also exhibited that the potent metabolite 4 had non-competitive modes of action. Linkage of the hydroxymethyl group in the C-3 and C-4 positions on the lactone ring probably enhances the tyrosinase inhibitory effect of 4-methylumbelliferone (5). Thus, the novel coumarin analog 4 is an interesting new class of tyrosinase inhibitory candidates that requires further examination. [ABSTRACT FROM AUTHOR]

In the study, the optimal values of the ratio of the distance between particles to the particle size in the radiation-heterogeneous radiolysis of water in nano-Me and nano-MeO systems were determined. In those systems, the effect of water density and system temperature on the radiation-chemical release of molecular hydrogen obtained from thermal and radiation-thermal decomposition of water was considered. The article also determined the effect of particle sizes and the type of sample taken on the radiation chemical yield of molecular hydrogen. In the presented article, the change of molecular hydrogen according to adsorbed water and catalyst was studied. Thus, in the case of a suspension of nano-zirconium in water, the energy of electrons emitted from the metal is completely transferred to water molecules, which leads to an increase in the yield of hydrogen. When radiolysis of water in the presence of nano- metals, energy transfer can be carried out mainly with the participation of emitted electrons. Therefore, in the case of radiolysis of water in suspension with n-Zr, the yield of hydrogen increases by 5.4 times compared to the processes of radiolysis in an adsorbed state. However, in radiation-heterogeneous processes of obtaining hydrogen from water in contact with metal systems, it is necessary to take into account that as a result of these processes surface oxidation occurs and after a certain time the systems are converted to n-Me-MeO+H2Oliq. systems. For nano sized oxide compounds, the mean free path of secondary electrons formed as a result of primary processes of interaction of quanta with atoms is commensurate with the particle sizes of nano-oxides (λ ≈ R&lowbar;(H-oxides)). Further, these electrons interact with the electronic subsystem of silicon. For nanocatalysts, the length of free paths of secondary and subsequent generations of electrons is greater than the size of catalyst particles (R&lowbar;cat≤100nm). Usually, their energy is sufficient to conduct independent radiolytic processes in the contact medium of the catalyst. [ABSTRACT FROM AUTHOR]

(1) Background: Radioprotective agents have garnered considerable interest due to their prospective applications in radiotherapy, public health medicine, and situations of large-scale accidental radiation exposure or impending radiological emergencies. Cystamine, an organic diamino–disulfide compound, is recognized for its radiation-protective and antioxidant properties. This study aims to utilize the aqueous ferrous sulfate (Fricke) dosimeter to measure the free-radical scavenging capabilities of cystamine during irradiation by fast carbon ions. This analysis spans an energy range from 6 to 500 MeV per nucleon, which correlates with "linear energy transfer" (LET) values ranging from approximately 248 keV/μm down to 9.3 keV/μm. (2) Methods: Monte Carlo track chemistry calculations were used to simulate the radiation-induced chemistry of aerated Fricke–cystamine solutions across a broad spectrum of cystamine concentrations, ranging from 10−6 to 1 M. (3) Results: In irradiated Fricke solutions containing cystamine, cystamine is observed to hinder the oxidation of Fe2+ ions, an effect triggered by oxidizing agents from the radiolysis of acidic water, resulting in reduced Fe3+ ion production. Our simulations, conducted both with and without accounting for the multiple ionization of water, confirm cystamine's ability to capture free radicals, highlighting its strong antioxidant properties. Aligning with prior research, our simulations also indicate that the protective and antioxidant efficiency of cystamine diminishes with increasing LET of the radiation. This result can be attributed to the changes in the geometry of the track structures when transitioning from lower to higher LETs. (4) Conclusions: If we can apply these fundamental research findings to biological systems at a physiological pH, the use of cystamine alongside carbon-ion hadrontherapy could present a promising approach to further improve the therapeutic ratio in cancer treatments. [ABSTRACT FROM AUTHOR]

Radiolysis of the VVER coolant during the transition of hydrogen from the liquid phase into gas-vapor bubbles is calculated. It is found that the decrease in the concentration of hydrogen in the liquid phase occurs until the hydrogen flow into bubbles becomes comparable to the hydrogen production due to radiolysis. In this case, a jump in hydrogen concentration leads to a sharp restructuring of the entire pattern of time dependences of the concentrations of radiolysis products. This is especially true for the behavior of concentrations of O2 and H2O2, i.e., the main oxidants of the zirconium cladding of fuel elements. It is shown that the local oxygen concentration relative to the permissible value can increase by more than 1000 times when the reactor is operated at >50% Nnom power. Similar behavior is demonstrated by hydrogen peroxide H2O2. However, the increase in its relative concentration by the same time is slightly more than one order of magnitude. A significant local increase in the concentration of oxidizing products of the radiolysis of O2 and H2O2 in the coolant seems to be the main reason for the appearance of a white deposit on the cladding of VVER fuel elements near the 12th spacer grid. [ABSTRACT FROM AUTHOR]

Aqueous solutions are crucial to most domains in biology and chemistry, including in energy fields such as catalysis and batteries. Water‐in‐salt electrolytes (WISEs), which extend the stability of aqueous electrolytes in rechargeable batteries, are one example. While the hype for WISEs is huge, commercial WISE‐based rechargeable batteries are still far from reality, and there remain several fundamental knowledge gaps such as those related to their long‐term reactivity and stability. Here, we propose a comprehensive approach to accelerating the study of WISE reactivity by using radiolysis to exacerbate the degradation mechanisms of concentrated LiTFSI‐based aqueous solutions. We find that the nature of the degradation species depends strongly on the molality of the electrolye, with degradation routes driven by the water or the anion at low or high molalities, respectively. The main aging products are consistent with those observed by electrochemical cycling, yet radiolysis also reveals minor degradation species, providing a unique glimpse of the long‐term (un)stability of these electrolytes. [ABSTRACT FROM AUTHOR]

The results of study of gas formation at the radiation-thermal transformation of bituminous rocks of Kirmaku fields of Azerbaijan are adduced. The studies were carried out under the influence of γ-radiation and accelerated electrons in a wide range of temperatures (20–500°C), absorbed dose (0–260 kGy), and dose rate (1 and 470 Gy/s). The influence of temperature and adsorbed dose on the gas formation rate and content of products has been established. Estimates of technical and economic indicators of the process are given. The results of these studies allow the estimation of the potential of the radiation-thermal method for producing oil products for various purposes. [ABSTRACT FROM AUTHOR]

The present work involves the investigation of the synergistic effects of gamma irradiation, tensile stress and absorbed moisture on the radiolysis behaviors of silicone foams by experiments and theoretical simulations. For both the pristine and dehydrated samples, the permanent tensile set increases with the initial tensile strain. Further analysis uncovers that the dehydrated samples exhibit greater permanent tensile sets, lower further elongation and higher Young's modulus than the counterparts of the pristine samples with the same initial tensile strain and gamma dose, verifying the vital synergistic effects on crosslinking network and aggregation structures caused by moisture and gamma radiation. The synergistic effects unveiled by reactive molecular dynamics at the atomic scale are due to the moisture-induced neutralization and stabilization of the macromolecular radicals. The steric hindrance of moisture located at the interface of silica and polymer chains also conduces to the observed synergistic effects due to the inhibited crosslinking reactions. [ABSTRACT FROM AUTHOR]

[177Lu]Lu-PSMAI&T is widely used for the radioligand therapy of metastatic castration-resistant prostate cancer (mCRPC). Since this kind of therapy has gained a large momentum in recent years, an upscaled production process yielding multiple patient doses in one batch has been developed. During upscaling, the established production method as well as the HPLC quality control were challenged. A major finding was a correlation between the specific activity and the formation of a pre-peak, presumably caused by radiolysis. Hence, nonradioactive reference standards were irradiated with an X-ray source and the formed pre-peak was subsequently identified as a deiodination product by UPLC-MS. To confirm the occurrence of the same deiodinated side product in the routine batch, a customized deiodinated precursor was radiolabeled and analyzed with the same HPLC setup, revealing an identical retention time to the pre-peak in the formerly synthesized routine batches. Additionally, further cyclization products of [177Lu]Lu-PSMAI&T were identified as major contributors to radiochemical impurities. The comparison of two HPLC methods showed the likelihood of the overestimation of the radiochemical purity during the synthesis of [177Lu]Lu-PSMAI&T. Finally, a prospective cost reduction through an optimization of the production process was shown. [ABSTRACT FROM AUTHOR]