Radiation-induced Reactions Research Articles

Radiation-induced skin reactions: oxidative damage mechanism and antioxidant protection.

According to official statistics, cancer remains the main reason of death and over 50% of patients with cancer receive radiotherapy. However, adverse consequences after radiation exposure like radiation-induced skin reactions (RISR) have negative or even fatal impact on patients' quality of life (QoL). In this review we summarize the mechanisms and managements of RISRs, a process that involve a variety of extracellular and intracellular signals, among which oxidative stress (OS) are now commonly believed to be the initial part of the occurrence of all types of RISRs. As for the management of RISRs, traditional treatments have been widely used but without satisfying outcomes while some promising therapeutic strategies related to OS still need further researches. In the context we discuss how OS leads to the happening of RISRs of different types, hoping it can shed some light on the exploration of new countermeasures.

Time-resolved observation of DHR123 nano-clay radio-fluorogenic gel dosimeters by photoluminescence-detected pulse radiolysis.

The importance of real-time dose evaluation has increased for recent advanced radiotherapy. However, conventional methods for real-time dosimetry using gel dosimeters face challenges owing to the delayed dose response caused by the slow completion of radiation-induced chemical reactions. In this study, a novel technique called photoluminescence-detected pulse radiolysis (PLPR) was developed, and its potential to allow real-time dose measurements using nano-clay radio-fluorogenic gel (NC-RFG) dosimeters was investigated. PLPR is a time-resolved observation method, and enables time-resolved fluorescence measurement. NC-RFG dosimeters were prepared, typically consisting of 100 μM dihydrorhodamine 123 (DHR123) and 2.0 wt.% nano-clay, along with catalytic and dissolving additives. We successfully achieved time-resolved observation of the increase in fluorescence intensity upon irradiation of the dosimeter. Dose evaluation was possible at 1 s after irradiation. The dose-rate effect was not observed for the deoxygenated dosimeter, but was observed for the aerated dosimeter. Besides the dose-rate effect, linear dose responses were obtained for both conditions. Furthermore, we made a novel observation of a decay in the fluorescence intensity over time in the early stages which named fluorescence secondary loss (FSL) and elucidated the conditions under which this phenomenon occurs.

Gel dosimetry: An overview of dosimetry systems and read out methods

Gel dosimetry has emerged over the past three decades in response to a growing need in high-precision radiotherapy to assess, in three dimensions, the absorbed radiation dose, as would be administered in cancer patients. Radiation-induced reaction mechanisms are dependent on the class of gel dosimeter, with four classes emerging as primary dosimeters for use in radiation therapy dose verification: (i) Fricke gel dosimeters contain a Fricke solution consisting of ammonium iron (II) sulfate in an acidic solution of sulfuric acid. In Fricke systems an oxidation of ferrous ions results in a change in the nuclear magnetic resonance (NMR) relaxation rate, which enables reading out Fricke gel dosimeters by use of MRI. The radiation-induced oxidation in Fricke gel dosimeters can also be visualized by adding a redox indicator. (ii) Polymer gel dosimeters exploit the radiation induced polymerization reaction of vinyl monomers and are predominantly read out by quantitative MRI or X-ray CT. (iii) Radiochromic dosimeters do not demonstrate a significant radiation-induced change in NMR properties but can be scanned by use of optical scanners (optical CT). In contrast to Fricke gel dosimeters, radiochromic gel dosimeters do not rely on the oxidation of a metal ion but exhibit a color change upon radiation. (iv) Radiofluorogenic dosimeters become fluorescent when exposed to ionizing radiation and can be read out with a planar scanning light beam. Likewise, the imaging modality used to extract quantitative dose information depends on the class of dosimeter being used, and three primary imaging modalities have emerged in this context: quantitative MRI, x-ray CT, and optical CT imaging. The accuracy and precision of the dose information extracted from gel dosimetry systems depends on both the dosimetric properties of the gel dosimeters and the readout technique, and the optimal readout method depends on the gel dosimeter response. Despite remaining an active field of research and illustrations of the application of gel dosimetry for the validation of clinical dose distributions, the utilizatio of gel dosimetry as a routine clinical dosimeter has been rather limited. However, with the introduction of new radiotherapy techniques that focus on organ motion compensation, new fractionation schemes, and extreme dose rates, the need for 3D radiation dosimetry is apparent. Even with the need for 3D dosimetry being apparent, gel dosimetry faces continued challenges in areas regarding the extraction of reproducible, accurate, and precise dose information. This review paper focuses on an introduction to gel dosimeter classes; a detailed examination of the three readout techniques with emphasis on the achievable accuracy, precision, and optimization of readout parameters; an outlook on future applications in emerging new radiotherapy techniques. We note that the introduction of theragnostic hybrid MRI-Linacs that combine an MRI-scanner and a clinical linear accelerator create new opportunities for inline polymer gel dosimetry. Likewise, the use of cone beam CT on linear accelerators opens up the possibility to read out gel dosimeters on the linac. Multiple optical CT designs have shown that optical CT gel dosimetry is eminently capable of providing high quality dosimetric information from clinically relevant treatment regimes. As a result, gel dosimetry provides exciting opportunities for 3D radiation dosimetry that were not available even a few years ago. The unique feature set of a properly executed gel dosimetry workflow allows for the extraction of dosimetric information, in 3D, that is not possible with any other dosimetry system and hence gel dosimetry provides exciting opportunities for clinical and research work in the area of radiation dose measurement.

Assembly Regulates Gamma Radiation Polymerization of Polytelluoxane.

Regulating chemical drug's responsiveness to gamma radiation is crucial for achieving better therapeutic effects in cancer treatment. Most research focused on thermodynamic chemical structure design, while little attention was paid to kinetic regulate strategy, which possesses greater universality and security. In this study, we achieved a kinetic-based regulate strategy of gamma radiation reaction, through the construction of microphase environment during polymerization of polytelluoxane (PTeO). We designed hydrophobic segments forming large compound micelles (LCMs) assembly to create kinetically favorable higher concentration for radiation-induced reaction. It exhibited a > ten times higher responsiveness and, as far as we know, merely required a minimum dosage of 5 Gy for polymerization to occur. What's more, by taking advantages of the assembly change with Te-O hydrophilic segments and gamma radiation, polymerization became milder with lower polydispersity than previous methods. Such kinetic-based regulate strategy could offer a novel perspective on the design of radiation-responsive chemoradiotherapy and other radiation-induced chemical process.

Lignin hydrogel sensor with anti-dehydration, anti-freezing, and reproducible adhesion prepared based on the room-temperature induction of zinc chloride-lignin redox system

In recent years, flexible sensors constructed mainly from hydrogels have received increasing attention. However, conventional hydrogels need to be prepared by high-temperature or radiation-induced polymerization reactions, which limits their practical applications due to their suboptimal electrical conductivity and weak mechanical properties. In this paper, using sodium lignosulfonate as the raw material, a dynamic catechol-quinone redox system formed by lignin‑zinc ions was constructed to initiate rapid free radical polymerization of acrylamide (AM) monomer at room temperature. In addition, Deep eutectic solvent (DES) can form a strong hydrogen bonding network within the molecules and between the molecules of the hydrogel, resulting in a hydrogel with good tensile properties (hydrogel elongation at break of 727.19 %, breaking strength of 84.09 kPa), and provides the hydrogel with high electrical conductivity, anti-dehydration, anti-freezing, and anti-bacterial properties. Meanwhile, the addition of lignin also improved the adhesion and UV resistance of the hydrogel. This hydrogel assembled into a flexible sensor can sense various small and large amplitude movements such as nodding, smiling, frowning, etc., and has a wide range of applications in flexible sensors.

Biological effect of dual-frequency laser pulse radiation during pre-sowing treatment of rice seeds at early stages of development under stressful environmental conditions

The biological effect of two-frequency laser pulsed radiation produced on copper vapor during pre-sowing treatment of rice seeds of Veles and Leader varieties at early stages of development in extreme stressful environmental conditions has been studied. The copper vapor laser used in the experiment had the following output characteristics: wavelengths of 510.6 nm (green radiation line) and 578.2 nm (yellow radiation line), pulse duration of 15 ns, repetition frequency of 10 kHz, total pulse power of 10 kW, energy-power ratio between the green and yellow radiation lines 3/1 The interaction of laser radiation with wavelengths of 510.6 and 578.2 nm in the nonlinear medium of the seed caused the formation of additional wavelengths: a total wavelength of 271 nm (ultraviolet radiation) and a difference wavelength of 4.37 microns. Exposure to each of the four wavelengths in its spectral range could lead to the initiation of at least four radiation-induced biochemical reactions. It is shown that pre-sowing treatment of rice seeds with two-frequency laser pulsed radiation for 5–20 seconds had a stimulating effect on the growth and development of rice (the greatest effect was when exposed to 5–10 seconds), and also increased its stability when grown in extreme stressful environmental conditions (moisture deficiency, depleted soil) at early stages of development.

Bismuth Oxychloride Nanoflakes Based Wearable Colorimetric Sensors for Efficient Monitoring of UV Exposure

Ultraviolet radiation from sunlight is essential for human health in many ways such as facilitating vitamin D synthesis while excessive exposure can cause adverse effects such as premature aging, sunburn, and skin cancers. In the USA, between 2007 and 2011, nearly five million adults were treated for skin cancer annually with average treatment costs of $8.1 billion each year. Hence, monitoring daily exposure to sunlight is essential to avoid developing health risks. Colorimetric UV sensors change color as a function of UV exposure, provide onsite information about the level of exposure, and can act as a personal wearable device to assist in making informed decisions on sunlight exposure. These sensors utilize radiation-induced reactions on a dye to produce a color change. We developed a BiOCl based wearable UV sensor for monitoring UV exposure where a white-to-black color transformation is induced due to the creation of oxygen vacancies in BiOCl. This color transformation is not quantifiable in bulk BiOCl; hence BiOCl was purposely dispersed on filter paper to form petal-like nanostructures that help quantify the color change. Four different dye molecules, 6-carboxyfluorescein, 5-carboxyfluorescein, rhodamine-B, and Prussian blue were evaluated, where 6-carboxyfluorescein gave the best color contrast. The sensor responds to UVA, UVB, and UVC and with proper UV filters can be made selective for specific UV radiations. This unique colorimetric UV sensor can help manage personal UV exposure and reduce the risk of sun exposure ailments.Reference: Kyle Troche, Kannan Ramaiyan, Timothy J. Boyle, Fernando H. Garzon, “Bismuth Oxychloride Nanoflakes Enabled High Sensitivity Colorimetric UV Dosimetry” ACS Appl. Nano. Mater. 2023, 6, 7.

Radiation Dermatitis: Radiation-Induced Effects on the Structural and Immunological Barrier Function of the Epidermis.

An important hallmark of radiation dermatitis is the impairment of the mitotic ability of the stem/progenitor cells in the basal cell layers due to radiation-induced DNA damage, leading to suppressed cell renewal in the epidermis. However, this mechanism alone does not adequately explain the complex pathogenesis of radiation-induced skin injury. In this review, we summarize the latest findings on the complex pathogenesis of radiation dermatitis and correlate these with the clinical features of radiation-induced skin reactions. The current studies show that skin exposure to ionizing radiation induces cellular senescence in the epidermal keratinocytes. As part of their epithelial stress response, these senescent keratinocytes secrete pro-inflammatory mediators, thereby triggering skin inflammation. Keratinocyte-derived cytokines and chemokines modulate intercellular communication with the immune cells, activating skin-resident and recruiting skin-infiltrating immune cells within the epidermis and dermis, thereby orchestrating the inflammatory response to radiation-induced tissue damage. The increased expression of specific chemoattractant chemokines leads to increased recruitment of neutrophils into the irradiated skin, where they release cytotoxic granules that are responsible for the exacerbation of an inflammatory state. Moreover, the importance of IL-17-expressing γδ-T cells to the radiation-induced hyperproliferation of keratinocytes was demonstrated, leading to reactive hyperplasia of the epidermis. Radiation-induced, reactive hyperproliferation of the keratinocytes disturbs the fine-tuned keratinization and cornification processes, leading to structural dysfunction of the epidermal barrier. In summary, in response to ionizing radiation, epidermal keratinocytes have important structural and immunoregulatory barrier functions in the skin, coordinating interacting immune responses to eliminate radiation-induced damage and to initiate the healing process.

Topical Fibronectin - Novel Therapeutic Approach Has Been Formulated for Radiation Induced Skin Reactions

For a long time, radiation-induced skin reactions (RISR) or radiation ulcer (RU) were only encountered in patients undergoing radiation therapy. Nearly 90% of patients having received radiation therapy underwent moderate-to-severe skin reactions such as non-healing wounds, severely reducing patients' quality of life and adversely affecting their disease treatment. Wound healing is significantly delayed in irradiated skin. Fibronectin was the most significantly and consistently downregulated in radiation-damaged skin. From a murine model, we confirmed that radiation leads to decreased fibronectin expression in the skin as well as delayed wound healing. Topically fibronectin was found to significantly improve wound healing in irradiated skin and was associated with decreased inflammatory infiltrate and increased angiogenesis. Fibronectin treatment may be a useful adjunctive modality in the treatment of non-healing radiation wounds. Besides, this review study can be referenced for clinicians to treat RSIs to guide subsequent clinical application.

Effects of Azomethine Derivatives of 4,6-Di-tert-Butyl-2,3-Dihydroxybezaldehyde on Radiation-Induced Reactions Involving Alkyl and Alpha-Hydroxyalkyl Radicals

Effects of Azomethine Derivatives of 4,6-Di-tert-Butyl-2,3-Dihydroxybezaldehyde on Radiation-Induced Reactions Involving Alkyl and Alpha-Hydroxyalkyl Radicals

Perceptions of healthcare professionals on the use of Mepitel Film for the prevention of acute radiation dermatitis in breast cancer.

Randomized clinical trials support Mepitel Film (MF) as a prophylactic treatment for radiation dermatitis (RD) in patients undergoing breast radiotherapy. Although several studies have canvassed the opinion of patients on using MF, no such studies have been done to investigate the perception of healthcare professionals (HCPs). The objective of this study was therefore to investigate the perceptions of HCPs on MF as a treatment option for RD. Anonymized responses to a web-based survey sent to HCPs at a single institution managing patients using MF during breast radiotherapy were analyzed. Of the 28 HCPs contacted, 22 completed the survey, including 6 radiation oncologists (ROs), 11 radiation therapists (RTTs), and 5 nurses. Most HCPs reported MF was better at preventing severe RD than the standard of care and improved radiation-induced skin reactions (n = 20/22, 91%, and n = 19/22, 86%, respectively). MF was recommended for mastectomy patients without reconstruction (n = 15/21, 71%). The majority of HCPs believed that patients' families could be trained to apply and remove MF (n = 19/22, 86%). Many HCPs perceived that implementation of MF would be difficult in terms of maintaining patient flow and wide-scale implementation within their institution (n = 11/22, 50%, and n = 10/22, 46%, respectively). Most HCPs perceived that fewer than 50% of their patients could afford MF if priced at $100 CAD (n = 15/20, 75%). These findings provide insights into the possibility of MF to be incorporated into standard practice of care for RD. Although most HCPs were satisfied with MF as a prophylactic treatment for RD, there are concerns about its resource-intensive operationalization and financial accessibility to patients. Future research should focus on ways to improve HCP experience with MF and to improve its implementation into clinical settings as standard of care.

Effects of Azomethine Derivatives of 4,6-Di-tert-Butyl-2,3-Dihydroxybezaldehyde on Radiation-Induced Reactions Involving Alkyl and Alpha-Hydroxyalkyl Radicals

The effects of azomethine derivatives of 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde on the formation of radiolysis products of deaerated n-hexane and ethanol have been studied. It was shown that the catechol moiety in the tested compounds did not significantly affect their reactions with carbon-centered radicals. The aldimine group exhibited high activity as an α-hydroxyalkyl radical scavenger and low activity as a scavenger of alkyl radicals. The introduction of additional radical-inhibiting groups –OH, –SH, –NO2, and =N–NH– into the side fragment of a molecule led to a significant increase in the antiradical activity withrespect to various types of carbon-centered radicals.

Radiation-induced dry reforming: A negative emission process

The reaction between the most abundant greenhouse gases (GHG) to produce hydrogen might represent the most powerful and effective decarbonizing opportunity, if a low-carbon energy source is used to drive it. This is the case of methane (CH4) dry reforming (MDR) where its reaction with carbon dioxide (CO2) produces synthesis gas (syngas, a mixture of carbon monoxide and hydrogen). This study explores the feasibility of using ionizing radiation to induce the MDR reaction, at low temperatures and/or less energy demanding conditions. Additionally, the ionizing radiation is proposed to be supplied by nuclear power plants (NPPs), which are low-carbon reliable energy generation sources. Thus, the radiolysis of CO2, CH4 and their mixtures, under γ-irradiation was evaluated in the absence and presence of nickel catalysts. The radiation-induced MDR reaction and radiation-induced catalytic promotion were proven to take place at temperatures close to ambient though at low conversion, with yields below 1%. Since irradiation and heat can be provided by a nuclear power plant, this radiation-induced reaction establishes a connection between nuclear energy to renewable resources and enables a pathway for a decarbonized cleaner chemical industry, for producing green chemicals.

Immunomodulatory Effects of Histone Variant H2A.J in Ionizing Radiation Dermatitis

Histone variant H2A.J is associated with premature senescence after ionizing radiation (IR) and modulates senescence-associated secretory phenotype (SASP). Using constitutive H2A.J knock-out mice, the role of H2A.J was investigated in radiation dermatitis. H2A.J wild-type (WT) and knock-out (KO) mice were exposed to moderate or high IR doses (≤20 Gy, skinfold IR). Radiation-induced skin reactions were investigated up to 2 weeks post-IR at macroscopic and microscopic levels. H2A.J and other senescence markers, as well as DNA damage and proliferation markers, were studied by immunohistochemistry, immunofluorescence, and electron microscopy. After high-dose IR, protein-coding transcriptomes were analyzed by RNA sequencing, immune cell infiltration by flow cytometry, and gene expression by reverse transcription polymerase chain reaction in (non-) irradiated WT versus KO skin. In WT skin, epidermal keratinocytes showed time- and dose-dependent H2A.J accumulation after IR exposure. Unexpectedly, stronger inflammatory reactions with increased epidermal thickness and progressive hair follicle loss were observed in irradiated KO versus WT skin. Clearly more radiation-induced senescence was observed in keratinocyte populations of KO skin after moderate and high doses, with hair follicle stem cells being particularly badly damaged, leading to follicle atrophy. After high-dose IR, transcriptomic analysis revealed enhanced senescence-associated signatures in irradiated KO skin, with intensified release of SASP factors. Flow cytometric analysis indicated increased immune cell infiltration in both WT and KO skin; however, specific chemokine-mediated signaling in irradiated KO skin led to more neutrophil recruitment, thereby aggravating radiation toxicities. Increased skin damage in irradiated KO skin led to hyperproliferation, abnormal differentiation, and cornification of keratinocytes, accompanied by increased upregulation of transcription-factor JunB. Lack of radiation-induced H2A.J expression in keratinocytes is associated with increased senescence induction, modulation of SASP expression, and exacerbated inflammatory skin reactions. Hence, epigenetic H2A.J-mediated gene expression in response to IR regulates keratinocyte immune functions and plays an essential role in balancing the inflammatory response during radiation dermatitis.

Radiation-induced isomerization reaction mechanism of hydrocarbons on the surface of solid acid

This paper's goal is to investigate how petroleum's n-alkane isomerization reaction occurs on the surface of a solid nanocatalyst. In this experiment, the isomerization of aromatic-rich crude oil is being studied as a result of radiation exposure. It was discovered that sodium-rich bentonite –solid acid, from the Alpoid deposit works well as a catalyst for refining petroleum. Possible mechanisms of the radio-catalytic reaction that converts n-alkanes to branched hydrocarbons have been researched by methods of FT- IR spectroscopy and gas chromatography. The effect of acidity type of the nanostructured bentonite clay on Lewis acid cites is proposed to explain observed results. Additional radiation energy, which is mainly generated due to the nanobentonite volume, results in a more efficient aromatic- rich petroleum radiolysis process. Also, it was investigated the dynamics of dose –dependent changes in the amount of branched hydrocarbons. One of the primary objectives of this research work is increasing the efficiency of transformation of adsorbed beam energy in solid phase to the system and improvement of hydrocarbon isomerization reactions in crude oil. The results of hydrocarbon transformations are discussed in terms of the behavior of excited electrons in solids. Novel eco-friendly nanocatalyst creates new opportunities for hydrocarbons with multi- branched structures.

Development of organic RPL dosimeters based on fluorescent products of the radiation-induced reaction of 2′,7′-dichlorofluorescein diacetate

In this study, we achieved a shift in the fluorescence wavelength of the organic molecules by X-ray irradiation and fabricated organic materials for radiation dosimetry, focusing on the radiation-induced radical oxidation of 2′,7′-dichlorofluorescein-diacetate (DCFHDA). We doped DCFHDA into processable and transparent polymers to develop a novel tissue-equivalent dosimeters with 3D measurement capabilities. Photoluminescence spectra of the organic materials were measured before and after X-ray irradiation, and their sensitivities to X-rays were compared based on the changes in their fluorescence intensity. Fluorescent molecules were produced from DCFHDA upon X-ray irradiation, and the material was sensitive to X-rays at doses of up to 6 kGy. Furthermore, trichloroacetic acid doping enhanced the dose sensitivity of the material by promoting the radical reaction, which indicates that it can be used as a sensitizer. These results indicate that the fluorescence wavelengths of DCFHDA switched to those of another fluorescent molecule, i.e., the achievement of radiophotoluminescence (RPL). We achieved an organic RPL (ORPL) and showed the possibility of ORPL that can be utilized in dosimetry in radiotherapy.

Radiation induced skin reactions in primary cutaneous lymphoma patients: A review

This review highlights the issue of radiation-induced skin reactions (RISR), emphasizes the high frequency of RISR in patients with cutaneous lymphomas undergoing radiation therapy, and analyzes numerous pathological processes that occur in the skin as a result of ionizing radiation exposure. The review systematically examines external and internal factors influencing the development of RISR, compares diagnostic methods, discusses preventive measures and treatments for radiation dermatitis, and describes the mechanisms of action for drugs used in RISR prophylaxis and treatment. RISR remains a significant problem in radiation therapy, characterized by a high frequency, a wide range of clinical manifestations, and an impact on patients quality of life. The mechanisms, diagnosis, prevention, and treatment of RISR are considered.

Feasibility and Tolerability of Adjuvant Capecitabine-Based Chemoradiation in Patients With Breast Cancer and Residual Disease After Neoadjuvant Chemotherapy: A Prospective Clinical Trial

Addition of adjuvant capecitabine improves overall survival for patients with breast cancer lacking pathologic complete response to standard-of-care neoadjuvant chemotherapy. Combining radiosensitizing capecitabine concurrent with radiation may further improve disease control, although the feasibility and tolerability of chemoradiation in this setting is unknown. This study aimed to determine the feasibility of this combination. Secondary objectives included the effect of chemoradiation on physician-reported toxicity, patient-reported skin dermatitis, and patient-reported quality of life compared with patients with breast cancer treated with adjuvant radiation. Twenty patients with residual disease following standard neoadjuvant chemotherapy were enrolled in a prospective single-arm trial and treated with adjuvant capecitabine-based chemoradiation. Feasibility was defined as ≥75% of patients completing chemoradiation as planned. Toxicity was assessed using Common Terminology Criteria for Adverse Events version 5.0 and the patient-reported radiation-induced skin reaction scale. Quality of life was measured using the RAND Short-Form 36-Item Health Survey. Eighteen patients (90%) completed chemoradiation without interruption or dose reduction. The incidence of grade ≥3 radiation dermatitis was 5% (1 of 20 patients). Patient-reported radiation dermatitis did not show a clinically meaningful difference following chemoradiation (mean increase, 55 points) compared with published reports of patients with breast cancer treated with adjuvant radiation alone (mean increase, 47 points). On the other hand, patient-reported quality of life demonstrated a clinically meaningful decline at the end of chemoradiation (mean, 46; SD, 7) compared with the reference population of patients treated with adjuvant radiation alone (mean, 50; SD, 6). Adjuvant chemoradiation with capecitabine is feasible and tolerable in patients with breast cancer. Although current studies using adjuvant capecitabine for residual disease following neoadjuvant chemotherapy have specified sequential treatment of capecitabine and radiation, these results support the conduct of randomized trials in this setting to investigate the efficacy of concurrent radiation with capecitabine and provide patient-reported toxicity estimates for trial design.

Understanding the Molecular Kinetics and Chemical Equilibrium Phase of Frozen CO during Bombardment by Cosmic Rays by Employing the PROCODA Code

Within the cold regions of space, ices that are enriched with carbon monoxide (CO) molecules are exposed to ionizing radiation, which triggers new reactions and desorption processes. Laboratory studies on astrochemical ices employing different projectiles have revealed the appearance of several new species. In this study, we employed the upgraded PROCODA code, which involves a calculation phase utilizing thermochemistry data, to map the chemical evolution of pure CO ice irradiated by cosmic-ray analogs. In the model, we have considered 18 different chemical species (six observed: CO, CO2, C3, O3, C2O, and C5O3; 12 unobserved: C, O, C2, O2, CO3, C3O, C4O, C5O, C2O2, C2O3, C3O2, and C4O2) coupled at 156 reaction routes. Our best-fit model provides effective reaction rates (effective rate constants, (ERCs)), branching ratios for reactions within reaction groups, several desorption parameters, and the characterization of molecular abundances at the chemical equilibrium (CE) phase. The most abundant species within the ice at the CE phase were atomic oxygen (68.2%) and atomic carbon (18.2%), followed by CO (11.8%) and CO2 (1.6%). The averaged modeled desorption yield and rate were 1.3e5 molecules ion−1 and 7.4e13 molecules s−1, respectively, while the average value of ERCs in the radiation-induced dissociation reactions was 2.4e-1 s−1 and for the bimolecular reactions it was 4.4e-24 cm3 molecule−1 s−1. We believe that the current kinetics study can be used in future astrochemical models to better understand the chemical evolution of embedded species within astrophysical ices under the presence of an ionizing radiation field.

Reaction mechanisms of Sn-complex-side-chain polymer used for extreme ultraviolet lithography, studied by electron pulse radiolysis and γ-radiolysis

The development of highly sensitive resists containing tin, which has a large EUV absorption cross section, has recently attracted considerable attention in EUV lithography. The effective utilization of secondary electrons is required for the development of high-performance resists. It is important to design resist materials on the basis of the mechanism of radiation chemical reactions. In this study, the radiation-induced reactions of tetraphenyltin (TPSn), triphenylsulfonium triflate (TPS-Tf), and the copolymer of triphenyl(4-vinylphenyl) stannane (TPSnSt) and 4-methacryloxyphenyldiphenylsulfonium triflate (MAPDPS-Tf) were investigated by electron pulse radiolysis and γ-radiolysis in controlled reaction systems. The decomposed products were analyzed by high-performance liquid chromatography. The G values of decomposed products were determined. For the copolymer, the holes generated by ionizing radiations moved to Sn units and electrons moved to TPS-Tf units. The tin complex side chain decomposed, producing benzene after hole transfer.