Initial Reaction Research Articles

A comparative study on the degradation of carbamazepine by UV laser/chlorine and UV laser/PS processes: Performance and mechanisms

Residual carbamazepine (CBZ) in water is difficult to remove through conventional treatment processes, threatening the safety of drinking water. Ultraviolet-based advanced oxidation processes (UV-AOPs) have shown promise in removing refractory organic pollutants, while the low energy and efficiency of traditional mercury lamps hinder their practical applications. In this study, the performance and mechanism of an intensive-energy light source, UV laser, were systematically explored in UV-AOPs (laser/chlorine, laser/persulfate (PS)). It was found that UV laser exhibited a significantly activating ability for chlorine and PS due to its precise wavelength and high pulse energy. When exposed to UV laser (266 nm, 4.2 mW/cm2) combined with 200 μM chlorine and PS, the kinetic rate constants for the degradation of 10 μM CBZ were determined to be 3.160 × 10-3 and 1.227 × 10-3 s−1, respectively. The degradation of CBZ was dominated by hydroxyl radicals (60.98 %) and sulfate radicals (23.15 %) in laser/PS system, while in laser/chlorine system, hydroxyl radicals (54.90 %), chlorine radicals (27.43 %), and chlorine oxide radicals (13.81 %) were primary reactive species. Furthermore, both the laser/chlorine and laser/PS systems demonstrated compatibility with a wide pH range of 5.0–9.0 and high resistance to anionic interference. Moreover, the electrophilic and nucleophilic sites of CBZ and energy barrier of the initial reaction were calculated based on the density functional theory (DFT). Additionally, the degradation pathways of CBZ and the toxicity of transformation products in laser/chlorine and laser/PS processes were proposed and evaluated. These results demonstrated that the UV laser-based processes exhibited promising prospects in eliminating refractory organic pollutants in water treatment.

Photodegradation of 2-chlorodibenzo-p-dioxin (2-CDD) on the surface of municipal solid waste incineration fly ash: Kinetics and product analysis

Considering that waste incineration fly ash is the main carrier of dioxins and can migrate over long distances in the atmosphere, it is of great significance to study the photochemical transformation behavior of dioxins on the surface of fly ash. In this work, 2-chlorodibenzo-p-dioxin (2-CDD) was selected to conduct a systematic photochemical study. The influence of various factors on the photodegradation of 2-CDD were first explored, and the results showed that small particle size of fly ash, low concentration of 2-CDD and appropriate level of humidity were more conducive to photodegradation, with the highest degradation percentage reaching 76%–84%. The components of fly ash (Zn (Ⅱ), Al (Ⅲ), Cu (Ⅱ) and SiO2) also had a certain promoting effect on the degradation of 2-CDD, which increases the degradation efficiency by 10%–20%, because they could act as effective photocatalysts to produce free radicals for reaction. With a higher total light exposure intensity, natural light environments led to a more complete degradation of 2-CDD than laboratory Xe lamp irradiation (90% degradation Vs. 79% degradation). Based on chemical probe and radical quenching experiment, hydroxyl radical also contributed to 2-CDD photodegradation on fly ash. A total of 16 intermediate products were detected by mass spectrometry analysis, and four initial reaction pathways of 2-CDD were speculated in the process, including dechlorination, ether bond cleavage, hydroxyl substitution, and hydroxyl addition. According to the results of density functional theory calculation, the reaction channels of ether bond cleavage and •OH attack were determined. The toxicity assessment software tool (TEST) was used to assess the toxicity and bioconcentration coefficient of reaction products, and it was found that the overall toxicity of the photodegradation products was reduced. This study would provide new insights into the environmental fate of dioxins during long-range atmospheric migration process.

Tricarboxylic Acid Cycle Intermediates and Individual Ageing.

Anti-ageing biology and medicine programmes are a focus of genetics, molecular biology, immunology, endocrinology, nutrition, and therapy. This paper discusses metabolic therapies aimed at prolonging longevity and/or health. Individual components of these effects are postulated to be related to the energy supply by tricarboxylic acid (TCA) cycle intermediates and free radical production processes. This article presents several theories of ageing and clinical descriptions of the top markers of ageing, which define ageing in different categories; additionally, their interactions with age-related changes and diseases related to α-ketoglutarate (AKG) and succinate SC formation and metabolism in pathological states are explained. This review describes convincingly the differences in the mitochondrial characteristics of energy metabolism in animals, with different levels (high and low) of physiological reactivity of functional systems related to the state of different regulatory systems providing oxygen-dependent processes. Much attention is given to the crucial role of AKG and SC in the energy metabolism in cells related to amino acid synthesis, epigenetic regulation, cell stemness, and differentiation, as well as metabolism associated with the development of pathological conditions and, in particular, cancer cells. Another goal was to address the issue of ageing in terms of individual characteristics related to physiological reactivity. This review also demonstrated the role of the Krebs cycle as a key component of cellular energy and ageing, which is closely associated with the development of various age-related pathologies, such as cancer, type 2 diabetes, and cardiovascular or neurodegenerative diseases where the mTOR pathway plays a key role. This article provides postulates of postischaemic phenomena in an ageing organism and demonstrates the dependence of accelerated ageing and age-related pathology on the levels of AKG and SC in studies on different species (roundworm Caenorhabditis elegans, Drosophila, mice, and humans used as models). The findings suggest that this approach may also be useful to show that Krebs cycle metabolites may be involved in age-related abnormalities of the mitochondrial metabolism and may thus induce epigenetic reprogramming that contributes to the senile phenotype and degenerative diseases. The metabolism of these compounds is particularly important when considering ageing mechanisms connected with different levels of initial physiological reactivity and able to initiate individual programmed ageing, depending on the intensity of oxygen consumption, metabolic peculiarities, and behavioural reactions.

VOx@ graphene electro-catalysts for water splitting and dopamine sensing

Vanadium oxide@graphene (VOG) composites were synthesized using facile hydrothermal method by varying the synthesis time from 6 to 24 h. The samples with best catalytic characteristics were reprepared by replacing graphene oxide with N-doped graphene in the initial hydrothermal reaction. The role of graphene/N-doped graphene in determining the catalytic properties of vanadium oxide was effectively studied using various characterizations viz. X-ray diffraction, Fourier Transform Infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Maximum hydrogen evolution reaction (HER) activity with high current density of –31.07 mA/cm2 (Tafel slope = 162 mVdec−1) has been achieved for VONG-24 sample, indicating Volmer reaction as rate determining step. The high electrochemical surface area (ECSA) of VOG-24 sample in 1 M KOH corroborated the enhanced current density of 144.90 mA/cm2 (Tafel slope = 83 mVdec−1) for maximum oxygen evolution reaction (OER) activity. The VOG12/GCE sample with a 0.29 μM limit of detection (LOD) proved to be the best electrochemical sensor for dopamine (DA) in a wide linear detection range i.e., 1–150 μM. Both catalytic as well as sensor responses of VOG samples were deeply influenced by the amount of O-species along with relative ratios of the V3+, V4+ and V5+. The nature of the graphene in the initial mixture emerged as a crucial parameter in tailoring the vanadium valence state content in the composites.

‘Experience the destination in times of crisis’: lessons from the approach of DMOs to destination marketing from concept to practice

ABSTRACT The COVID-19 pandemic disrupted the established practices of DMOs. However, it also prompted a shift towards utilising the untapped potential and resources of regions, which could present unique opportunities for future destination marketing. The main goal was to explore the approach of DMOs to destination marketing and to the recovery of domestic tourism amid the COVID-19 pandemic in the context of experience marketing. This includes the initial reactions of the DMOs, their short-term plans, future plans, and long-term perspectives. The paper used desk research and conducted in-depth semi-structured interviews with key informants from regional Polish DMOs, specifically, the chief marketing officers and the presidents of the DMOs. The results confirm the use of an experience-based approach in destination marketing to achieve domestic tourism recovery. The destinations have offered various forms of involvement during tourist experiences, including: active or passive participation, absorption, and immersion. Additionally, DMOs can strategize for more sustainable, eco-friendly, and small-scale tourism through experience marketing.

Unveiling Three Interconvertible Redox States of Boraphenalene.

Neutral 1-boraphenalene displays the isoelectronic structure of the phenalenyl carbocation and is expected to behave as an attractive organoboron multi-redox system. However, the isolation of new redox states have remained elusive even though the preparation of neutral boron(III)-containing phenalene compounds have been extensively studied. Herein, we have adopted an N-heterocyclic carbene ligand stabilization approach to achieve the first isolation of the stable and ambipolar 1-boraphenalenyl radical 1•. The 1-boraphenalenyl cation 1+ and anion 1- have also been electrochemically observed and chemically isolated, representing new redox forms of boraphenalene for the study of non-Kekulé polynuclear benzenoid molecules. Experimental and theoretical investigations suggest that the interconvertible three-redox-state species undergo reversible electronic structure modifications, which primarily take place on the polycyclic framework of the molecules, exhibiting atypical behavior compared to known donor-stabilized organoboron compounds. Initial reactivity studies, aromaticity evaluations, and photophysical studies show redox-state-dependent trends. While 1+ is luminescent in both the solution and solid states, 1• exhibits boron-centered reactivity and 1- undergoes substitution chemistry on the boraphenalenyl skeleton and serves as a single-electron transfer reductant.

Immunothérapie allergénique aux venins d’hyménoptères : stop ou encore ?

Hymenoptera venom immunotherapy (VIT) is the only curative treatment for preventing effectively severe insect sting anaphylaxis. The overall cumulative risk of relapse at 10 years after discontinuing VIT is estimated at 17 %, but is mainly dependent on associated risk factors. The decision to discontinue or continue VIT depends on the patient's individual risk profile which takes into account the elements related to the initial sting reaction (severity, stinging insect), the characteristics of the patient himself (exposure, age, medical problems or treatments), the tolerance and efficacy of VIT and the presence or absence of certain biomarkers. Maintenance of an ongoing VIT is possible in case of treated severe cardio-respiratory diseases, stabilized systemic autoimmune diseases and tumors or in remission, primary or acquired immune deficits and immunomodulatory or immunosuppressive treatments. Lifelong VIT is indicated in case of clonal mast cell disorder or systemic mastocytosis, for any patient having experienced very severe or near-fatal hymenoptera venom anaphylaxis, and possibly also in case of hereditary alpha-tryptasemia, with the aim of protecting the patient from a severe, potentially fatal anaphylactic relapse.

The use of corporate social responsibility in response to product‐harm crisis: How do stock market reactions matter?

AbstractThe initial stock market reaction to a product‐harm crisis is an important factor motivating firms to engage in corporate social responsibility (CSR). By analyzing event data on product‐harm crises in Chinese listed companies spanning from 2009 to 2019, we uncover evidence that crisis‐related abnormal returns have a significant negative association with the subsequent growth of CSR. Importantly, we find that this negative relationship is especially pronounced for firms that have a greater need to restore moral legitimacy, such as those receiving high levels of media favorability and positive analyst recommendations. These findings offer novel insights into the motivations behind firms' increased investment in CSR following product‐harm crises from a legitimacy perspective.

Deep dive into the underlying cause of the carbon loss and the associated chemical processes in fatty acid hydrodeoxygenation over Ni@Hβ catalyst

Identification of the underlying cause of carbon loss in fatty acid hydrodeoxygenation (HDO) on the acidic catalyst is very important to understand the reaction mechanism and design high efficiency catalyst for biomass conversion. Herein, HDO reactions of palmitic acid catalyzed by Ni supported on mesoporous Beta (HBeta-M) zeolites with different acidities were investigated. It was found that a significant carbon loss (47.5%) occurred during the entire reaction process on Ni/HBeta-M catalyst with high acid density. This is because the hexadecyl ether intermediate was formed and trapped in the porous structure of the catalyst and interacted with strong acidic sites. On the Ni/HBeta-M-0.5 catalyst with medium acid density, carbon loss occurred in the initial reaction stage because hexadecanol was trapped in the porous catalyst. Investigations further demonstrated that the hexadecyl ether intermediate can also be converted to hexadecanol and hexadecane via hydrogenolysis on Brønsted acid and Ni sites.

Enhanced flame retardancy and thermal stability in flexible polyurethane foam through synergistic core-shell structured DBDPE@PMA particles

This research presents the synthesis of core–shell structured flame retardant particles, DBDPE@PMA, which combines the flame-retardant and toughening functions. These particles utilize decabromodiphenyl ethane (DBDPE) as the core and a copolymer of methyl methacrylate and acrylic acid (MMA-AA) as the shell, which are created via emulsion polymerization. The process involved an initial reaction of DBDPE@PMA with isocyanate, followed by foaming with polyether polyol to fabricate flame retardant, and the flexible polyurethane foam (P/D-FPUF) was thermally insulated. The study examined the influence of DBDPE@PMA on the flame retardancy properties of flexible polyurethane foam. Scanning electron microscopy confirmed the encapsulation of DBDPE by the polymer, resulting in a core–shell composite particle. The interaction between the carboxylic groups (–COOH) on the DBDPE@PMA shell and isocyanate enhanced the interfacial bonding, thereby increasing the foam's apparent density and ensuring better integration with the polyurethane matrix. However, DBDPE@PMA had aggregates on the foam matrix bubble holes, resulting in uneven bubble holes. DBDPE@PMA markedly improved the flame retardancy and thermal stability of the foam, compared to both pure polyurethane and foam containing solely DBDPE (10D-FPUF). The oxygen index value of the foam with 20% DBDPE@PMA (20P/D-FPUF) reached 33.6%, with UL-94 horizontal and Vertical burning level tests achieving the highest classifications. The char residue after thermal degradation increased significantly from 1.93% in pure foam to 5.06%. While the smoke density level rose, the duration to peak smoke density was prolonged to 78 s, offering an enhanced margin for evacuation during the initial stages of a fire.

Spiritual Surrender: Initial Appraisals of Cancer Diagnoses in Black Christian Women

The basis of the meaning-making model is that distress results from discrepancies between one’s global meaning system and one’s situational appraisals of negative life events. This model suggests a preventative function for religion when religious global beliefs inform situational appraisals in ways that minimize distress. Using consensual qualitative research, we evaluated the initial reactions to a cancer diagnosis of 29 Black Christian women. We examined how the women appraised the cancer diagnosis and how this appraisal was related to reported distress. Our results indicated that lower levels of distress were related to believing that God was faithful, while higher levels of distress were related to beliefs in retributive justice and cancer as a death sentence. Lower distress was further related to spiritual surrender, a religious coping practice that combines entrusting the outcome of one’s cancer experience to God and actively pursuing treatment. We discuss spiritual surrender as a collaborative religious coping strategy and highlight its importance in informing culturally sensitive psychological interventions.

Intersubunit communication in glycogen phosphorylase influences substrate recognition at the catalytic sites

Glycogen phosphorylase (GP) is biologically active as a dimer of identical subunits, each activated by phosphorylation of the serine-14 residue. GP exists in three interconvertible forms, namely GPa (di-phosphorylated form), GPab (mono-phosphorylated form), and GPb (non-phosphorylated form); however, information on GPab remains scarce. Given the prevailing view that the two GP subunits collaboratively determine their catalytic characteristics, it is essential to conduct GPab characterization to gain a comprehensive understanding of glycogenolysis regulation. Thus, in the present study, we prepared rabbit muscle GPab from GPb, using phosphorylase kinase as the catalyst, and identified it using a nonradioactive phosphate-affinity gel electrophoresis method. Compared with the half-half GPa/GPb mixture, the as-prepared GPab showed a unique AMP-binding affinity. To further investigate the intersubunit communication in GP, its catalytic site was probed using pyridylaminated-maltohexaose (a maltooligosaccharide-based substrate comprising the essential dextrin structure for GP; abbreviated as PA-0) and a series of specifically modified PA-0 derivatives (substrate analogs lacking part of the essential dextrin structure). By comparing the initial reaction rates toward the PA-0 derivative (Vderivative) and PA-0 (VPA-0), we demonstrated that the Vderivative/VPA-0 ratio for GPab was significantly different from that for the half-half GPa/GPb mixture. This result indicates that the interaction between the two GP subunits significantly influences substrate recognition at the catalytic sites, thereby providing GPab its unique substrate recognition profile.

Exothermic Reaction in the Cleaning of Wastewater by a Fe2O3/Coconut Shell Activated Carbon/H2O2 Heterogeneous Fenton-like System

Energy utilization in wastewater degradation has important implications for sustainability; however, efficient multiphase Fenton-like catalysts are still needed. In this study, a heterogeneous Fe2O3/coconut shell activated carbon (CSAC) Fenton-like catalyst was prepared and evaluated with respect to degradation performance and exothermic reaction for the treatment of organic wastewater. Fe2O3@CSAC retained the porous morphology of CSAS, and Fe2O3 was uniformly loaded on the surface of CSAS. In the reaction system, the degradation rate of wastewater was higher and a large amount of heat was released; therefore, it could be applied to the energy recovery from wastewater source heat pump technology. The degradation rate of 300 mL of o-phenylenediamine solution with a concentration of 0.04 mol·L−1 was 89.0% under 0.25 mol·L−1 H2O2, 532 g·L−1 Fe2O3@CSAC, pH 7.1, and an initial reaction temperature of 30 °C, elevated to 7.9 °C. These findings clearly demonstrate the degradation performance and exothermic laws of the Fe2O3@CSAC/H2O2 multiphase Fenton-like system.

Influence of Surface Segregation of Tin on the Phosphatability of Cold‐Rolled Steel Sheets

The increasing use of iron scrap to reduce greenhouse gas emissions results in the enrichment of steel with the tramp element Sn. However, the effect of Sn on phosphatase activity remains unclear. Therefore, this study aims to investigate the effect of the Sn content on the phosphatase activity of cold‐rolled steel plates. The phosphatability of the cold‐rolled steel sheets is evaluated by adding several tens of ppm of Sn. The surface characteristics of the materials are analyzed using X‐Ray photoelectron spectroscopy and transmission electron microscopy. Additionally, the reactivities of the materials in the phosphate treatment solution are assessed using an electrochemical evaluation method. Notably, a significant decrease in phosphatase activity is observed, which is attributed to the inhibition of the phosphate reaction by the Sn oxide layers formed on the steel sheet surface, with a layer thickness of a few nanometers. These Sn surface oxides can be removed by pickling with HCl, and the initial phosphate reaction occurs rapidly in areas where the oxides are removed.

Batch Fabrication and Interface Stabilization Accelerate Application of Skutterudite Thermoelectric Module for Power Generation

AbstractTo achieve the commercial application of high‐performance skutterudite (SKD) thermoelectric (TE) devices, breakthroughs in the batch fabrication of TE material and the realization of its stable bonding to the barrier layer are necessary. In this work, the large‐scale SKD bulks with excellent TE performance and decent homogeneity are prepared by melt‐spinning (MS) combined with a hot pressing process. Then, a modified two‐step sintering method is employed to effectively suppress the degree of initial interfacial reaction, resulting in a barrier layer/SKD joint that exhibits low contact resistivity (≈2µΩ·cm2) and high bonding strength (≈30 MPa) with no significant change after aging at 773 K for 30 days. Encouragingly, the joints welded with Mo50Cu50 electrodes also show high stability under the same aging conditions. Finally, the as‐fabricated 8‐pair module shows a highly competitive conversion efficiency of 9% under a temperature difference of 580 K. In addition, during a 360 h aging test with hot‐side temperature of 773 K, the module shows excellent stability. Overall, this work paves the way for batch fabrication of high‐performance SKD using MS and lays a solid foundation for the stable operation of SKD‐based modules.

Opinion: The Key Steps in the Origin of Life to the Formation of the Eukaryotic Cell.

The path from life's origin to the emergence of the eukaryotic cell was long and complex, and as such it is rarely treated in one publication. Here, we offer a sketch of this path, recognizing that there are points of disagreement and that many transitions are still shrouded in mystery. We assume life developed within microchambers of an alkaline hydrothermal vent system. Initial simple reactions were built into more sophisticated reflexively autocatalytic food-generated networks (RAFs), laying the foundation for life's anastomosing metabolism, and eventually for the origin of RNA, which functioned as a genetic repository and as a catalyst (ribozymes). Eventually, protein synthesis developed, leading to life's biology becoming dominated by enzymes and not ribozymes. Subsequent enzymatic innovation included ATP synthase, which generates ATP, fueled by the proton gradient between the alkaline vent flux and the acidic sea. This gradient was later internalized via the evolution of the electron transport chain, a preadaptation for the subsequent emergence of the vent creatures from their microchamber cradles. Differences between bacteria and archaea suggests cellularization evolved at least twice. Later, the bacterial development of oxidative phosphorylation and the archaeal development of proteins to stabilize its DNA laid the foundation for the merger that led to the formation of eukaryotic cells.

Severity of the initial acute drug reaction does not necessarily predict the severity of symptoms that may develop during a rapid drug desensitization to a platinum-based agent.

Severity of the initial acute drug reaction does not necessarily predict the severity of symptoms that may develop during a rapid drug desensitization to a platinum-based agent.

Diversity in fatty acid elongation enzymes: The FabB long-chain β-ketoacyl-ACP synthase I initiates fatty acid synthesis in Pseudomonas putida F1

The condensation of acetyl-CoA with malonyl-acyl carrier protein (ACP) by β-ketoacyl-ACP synthase III (KAS III, FabH) and decarboxylation of malonyl-ACP by malonyl-ACP decarboxylase are the two pathways that initiate bacterial fatty acid synthesis (FAS) in Escherichia coli. In addition to these two routes, we report that Pseudomonas putida F1 β-ketoacyl-ACP synthase I (FabB), in addition to playing a key role in fatty acid elongation, also initiates FAS invivo. We report that although two P.putida F1 fabH genes (PpfabH1 and PpfabH2) both encode functional KAS III enzymes, neither is essential for growth. PpFabH1 is a canonical KAS III similar to E.coli FabH whereas PpFabH2 catalyzes condensation of malonyl-ACP with short- and medium-chain length acyl-CoAs. Since these two KAS III enzymes are not essential for FAS in P.putida F1, we sought the P.putida initiation enzyme and unexpectedly found that it was FabB, the elongation enzyme of the oxygen-independent unsaturated fatty acid pathway. P.putida FabB decarboxylates malonyl-ACP and condenses the acetyl-ACP product with malonyl-ACP for initiation of FAS. These data show that P.putida FabB, unlike the paradigm E.coli FabB, can catalyze the initiation reaction in FAS.

Biomechanical properties of nasal tissues

Introduction. Plastic rhinosurgery and augmentation rhinoplasty are very relevant today. Especially in relation to patients with congenital saddle deformity of the nasal dorsum, as well as patients with iatrogenic disorders of the nose shape, which dramatically reduce the quality of human life. There are violations of the function of the nose. The purpose of the work. Purpose. Within the framework of the necessity of performing silicone implantation rhinoplasty, the strength, elastic and hyperelastic properties of the soft tissues of the nasal fascia and periosteum were studied, the dynamic viscosity of the tissues of the nasal fascia and periosteum was evaluated, determining their relaxation properties using elastic, hyperelastic and rheological models. Methods. Linear, bilinear (with two Young modules), exponential, hyperelastic (neohookean, Mooney-Rivlin, Ogden, Yeoh, polynomial and Veronda-Westmann) and elastic-viscous (Maxwell) models of biological tissues were used. We used the Mathcad 15.0 computer algebra system and the universal package of interdisciplinary programs ANSYS Multiphysics Software (version 2022 R2). The accuracy of replacing the properties of real tissues with the results of calculations was calculated on the basis of indicators of descriptive statistics (standard deviation, maximum absolute error, maximum relative error and correlation coefficient). Results. It is proved that the bilinear model for the exact reproduction of the stress-strain curve assumes at the molecular level of tissues an initial linear reaction of elastin fibers, passing at ε=εcr into the final linear reaction of the collagen matrix. It was found that the properties of the periosteum (correlation coefficient R=0.9999) and nasal fascia (correlation coefficient R=0.9999) are described most adequately by the 5-parametric polynomial model of the 2nd order and the Yeoh model of the 3rd order (R=0.999 and R=1, respectively), the least accurately by the simple 1-parameter neohookean model (R=0.898 for the periosteum and R=0.905 for the fascia). Among elastic models, the exponential dependence characterizes the behavior of nasal materials quite well. Conclusion. Biomechanically verified that the periosteum is thicker, stronger and more rigid than the fascia. The established very high viscosity values indicate the slowness of relaxation processes in tissues. The periosteum relaxes tension more slowly, which improves the result of implant fixation. On the contrary, the relaxation time of the periosteum is higher than that of the fascia, from which it is concluded that it is preferable not to cut the periosteum during subcostal implantation.

A novel method for predicting the thermal stabilization temperature of organic Rankine cycle system working fluids based on transition state theory

The use of organic working fluids in organic Rankine cycle (ORC) systems may lead to thermal decomposition, which negatively impacts system performance and safety. In this work, a simplified theoretical method based on the transition state theory is proposed to predict the ideal maximum thermal stabilization temperature of organic working fluids. This method involves considering the initial decomposition reaction of the working fluids and calculating the total reaction rate of the initial decomposition. By setting an acceptable decomposition rate, the ideal maximum thermal stabilization temperature of the working fluid can be determined. Using this method, the total reaction rate constants of several typical hydrocarbon, hydrofluorocarbon and siloxane working fluids were obtained in the temperature range of 300∼700 K. The predicted maximum operational temperatures were in good agreement with most experimental results. The branch ratio analyses show that C–C bond cleavage contributed mainly to the decomposition of hydrocarbons, the removal of HF and C–C bond cleavage contributed mainly to that of HFCs, and the Si–C bond cleavage contributed mainly to that of siloxanes. Only considering these main reactions in the reaction rate calculation can greatly reduce calculation cost without significantly impacting the prediction accuracy.