Types Of Reactions Research Articles

Final nanoparticle size distribution under unusual parameter regimes.

We explore the large-scale behavior of a stochastic model for nanoparticle growth in an unusual parameter regime. This model encompasses two types of reactions: nucleation, where n monomers aggregate to form a nanoparticle, and growth, where a nanoparticle increases its size by consuming a monomer. Reverse reactions are disregarded. We delve into a previously unexplored parameter regime. Specifically, we consider a scenario where the growth rate of the first newly formed particle is of the same order of magnitude as the nucleation rate, in contrast to the classical scenario where, in the initial stage, nucleation dominates over growth. In this regime, we investigate the final size distribution as the initial number of monomers tends to infinity through extensive simulation studies utilizing state-of-the-art stochastic simulation methods with an efficient implementation and supported by high-performance computing infrastructure. We observe the emergence of a deterministic limit for the particle's final size density. To scale up the initial number of monomers to approximate the magnitudes encountered in real experiments, we introduce a novel approximation process aimed at faster simulation. Remarkably, this approximating process yields a final size distribution that becomes very close to that of the original process when the available monomers approach infinity. Simulations of the approximating process further support the conjecture of the emergence of a deterministic limit.

Ultra-Small High-Entropy Alloy as Multi-Functional Catalyst for Ammonia Based Fuel Cells.

Ammonia fuel cells using carbon-neutral ammonia as fuel are regarded as a fast, furious, and flexible next-generation carbon-free energy conversion technology, but it is limited by the kinetically sluggish ammonia oxidation reaction (AOR), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER). Platinum can efficiently drive these three types of reactions, but its scale-up application is limited by its susceptibility to poisoning and high cost. In order to reduce the cost and alleviate poisoning, incorporating Pt with various metals proves to be an efficient and feasible strategy. Herein, PtFeCoNiIr/C trifunctional high-entropy alloy (HEA) catalysts are prepared with uniform mixing and ultra-small size of 2 ± 0.5nm by Joule heating method. PtFeCoNiIr/C exhibits efficient performance in AOR (Jpeak = 139.8 A g-1 PGM), ORR (E1/2 = 0.87V), and HER (E10 = 20.3 mV), outperforming the benchmark Pt/C, and no loss in HER performance at 100mA cm-2 for 200 h. The almost unchanged E1/2 in the anti-poisoning test indicates its promising application in real fuel cells powered by ammonia. This work opens up a new path for the development of multi-functional electrocatalysts and also makes a big leap toward the exploration of cost-effective device configurations for novel fuel cells.

Social Media in times of change: a three-period analysis of sentiment and engagement on the romanian ministry of education's online presence

Introduction: This research investigates the role of social media in institutional communication, with a focus on its effectiveness in engaging stakeholders within the educational sector. It analyzes the impact of digital transformation on public institutions, focusing on how governments' strategic communication during the COVID-19 pandemic, the adoption of digital platforms, and Facebook's role in Romanian public administration demonstrate social media's capabilities. It highlights the effectiveness of social media in spreading information, engaging public sentiment, and enhancing communication strategies during crises. Additionally, it addresses the challenges of combating misinformation and underscores the importance of developing tailored communication strategies. Methodology: The study investigates the engagement of the Romanian Ministry of Education on social media, especially Facebook, during the pre-pandemic, pandemic, and post-pandemic periods. It aims to discern shifts in communication strategies and public engagement by analyzing posting frequency, engagement rates, sentiment analysis, and reaction types, employing tools like Fanpagekarma and RStudio for data collection and analysis. Results: The analysis indicates an uptick in post frequency by the Ministry of Education during the pandemic, with sentiment analysis revealing a consistently positive tone. This suggests a strategic shift towards more optimistic messaging. Engagement rates showed considerable variation pre-pandemic but stabilized during and after the pandemic, indicating effective content resonance with the audience. Conclusions: The study underscores the significant role of social media in crisis communication, evidenced by increased engagement and strategic positive messaging. It recommends institutions continue utilizing social media for flexible communication strategies, suggesting that a balance of optimistic messaging with transparent discussions about challenges can boost public trust and engagement, aiding in the development of a well-informed and resilient society.

Recent Advances in Halogen-Metal Exchange Reactions.

ConspectusThe halogen-metal exchange reaction is a very powerful method for preparing functionalized organometallic reagents in the fields of organic and organometallic chemistry. Since its inception, significant interest has been directed toward the on-demand development of new halogen-metal exchange reactions, primarily through the upgrading of exchange reagents. The enduring quest for optimal reactivity, superior functional group compatibility, and innovative synthetic applications of exchange reagents remains a fundamental objective. In the past several years, the emergence of some significant discoveries in halogen-metal exchange reactions has proclaimed a renaissance to this field. This Account outlines the latest advances within the domain contributed by the Knochel group, including the main points as follows.The stereoretentive I/Li exchange on stereodefined secondary alkyl iodides was developed for the synthesis of nonstabilized chiral secondary alkyllithium reagents. This provided a straightforward method to access chiral organolithium reagents, which can be trapped by various electrophiles or transmetalated with other metals such as copper, zinc, and magnesium, thus enabling the stereoselective synthesis of a series of functionalized compounds and natural products.Faster halogen-magnesium and halogen-zinc exchanges in toluene were realized using a novel kind of exchange reagent complexed with lithium alkoxide. These highly efficient exchange reactions are much faster than traditional ones and performed in an industrially friendly solvent. These advantages are of great value in practical synthesis, paving the way for new developments in this evolving area.Halogen-lanthanide exchanges and their novel applications in organic synthesis were established. These new exchanges introduced the lanthanide metals into halogen-metal exchange reactions for the first time, thereby opening new avenues in synthetic chemistry. Building on these achievements, a comparative analysis of the exchange reaction rates by kinetic study has quantified the relationship between the electronegativity of metals and the rates of halogen-metal exchanges.Br/Na exchange in continuous flow was achieved using a hexane-soluble exchange reagent, 2-ethylhexylsodium. This approach effectively circumvented the poor solubility of the organosodium reagent, which has proven to be of significant practical value and greatly enhanced the synthetic utility of the organosodium reagent in organic synthesis.These remarkable breakthroughs as mentioned above are fueled mainly by upgrading the exchange reagents, resulting in the development of new halogen-metal exchange reactions and innovative applications in organic synthesis. Given the importance of halogen-metal exchanges in synthetic chemistry, the pursuit of other types of exchange reactions, particularly those involving new metals, will be in continuous demand. This Account provides a timely summary of recent progress and will undoubtedly inspire further advances to drive this research field forward.

Enantioselective Reductive Cyclization of Alkynyl-Tethered Cyclohexadienones Catalyzed by Rhodium Complexes.

Although various types of asymmetric cyclization reactions of 1,6-enynes have been established, simple asymmetric reductive cyclization remains underdeveloped. In this study, the enantioselective reductive cyclization of alkynyl-tethered cyclohexadienones (1,6-enynes) has been developed via a chiral pincer rhodium catalyst, affording cis-hydrobenzofurans and cis-hydroindoles with high enantioselectivities (90-99% ee). Furthermore, several synthetic applications and preliminary inhibitory activity studies against SARS-CoV-2 3CLpro are presented.

Well‐defined nanostructures of high entropy alloys for electrocatalysis

AbstractHigh‐entropy alloys (HEAs) have attracted significant attention for electrocatalytic energy conversion by virtue of their promisingly high efficiency, stability, and low cost. Recently, encouraging progress has been made in tuning the structure and composition of HEAs used in electrolyzers and fuel cells. However, the understanding on the synthetic methods and the structure‐property‐performance relationship of well‐defined HEAs nanostructures is still inadequate. To gain insight into the future research directions on HEAs for electrocatalysis, in this paper, the synthetic methods commonly used to obtain well‐defined HEAs nanostructures (0D nanoparticles, 1D nanowires, 2D nanosheets/nanoplates, 3D nanoporous structures, and other three‐dimensional morphologies) are first summarized. Then, the authors discuss the application of well‐defined HEAs nanostructures in several typical electrocatalytic reactions, including hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, alcohol oxidation reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, and formic acid oxidation reaction. Finally, a practical perspective on the future research directions on well‐defined HEAs nanostructured electrocatalysts is provided.

Photocatalytic Hydrosilylation over Pt@UiO-66-NH2: Enhanced Activity and Polymerization Kinetics.

Metal-organic frameworks (MOFs) have shown great research and application value in various types of hydrosilylation reactions. However, studies on photocatalysis-induced hydrosilylation using MOFs are extremely rare. Metal nanoparticles (MNPs)@MOFs are extensively studied for their excellent structural tunability and photocatalytic activity, but there are few reports on their application in photocatalytic hydrosilylation. Here, a novel photocatalyst consisting of platinum (Pt) nanoparticles immobilized in a MOF framework is synthesized and used for photocatalytic hydrosilylation. The effects of various factors on hydrosilylation conversion are investigated, including catalyst concentration, substrate ratio, and irradiation intensity. Furthermore, the photoreactivity of the synthesized Pt catalyst is evaluated in the presence of different concentrations of 2-chlorothixanthone as a photosensitizer. It is noteworthy that the conversion of the reaction increases with increasing catalyst concentration or photosensitizer concentration, whereas increasing the polymethylhydrosiloxane content does not lead to a significant increase in conversion. This study demonstrates the potential of MNPs@MOFs as efficient photocatalysts for photoinduced hydrosilylation reactions and paves the way for future applications in this area.

Tick salivary proteome and lipidome with low glycan content correlate with allergic type reactions in the zebrafish model

Ticks, as hematophagous ectoparasites, can manipulate host immune and metabolic processes, causing tick-borne allergies such as α-Gal syndrome (AGS). Glycolipids with bound galactose-alpha-1–3-galactose (α-Gal) are potential allergenic molecules associated with AGS. Nevertheless, proteins and lipids lacking α-Gal modifications may contribute to tick salivary allergies and be linked to AGS. In this study, we characterized the effect of deglycosylated tick salivary proteins without lipids on treated zebrafish fed with dog food formulated with mammalian (beef, lamb, pork) meat by quantitative proteomics analysis of intestinal samples. The characterization and functional annotations of tick salivary lipids with low representation of glycolipids was conducted using a lipidomics approach. Results showed a significant effect of treatment with saliva and saliva deglycosylated protein fraction on zebrafish abnormal or no feeding (p < 0.005). Treatment with this fraction affected multiple metabolic pathways, defense responses to pathogens and protein metabolism, which correlated with abnormal or no feeding. Lipidomics analysis identified 23 lipid classes with low representation of glycolipids (0.70% of identified lipids). The lipid class with highest representation was phosphatidylcholine (PC; 26.66%) and for glycolipids it corresponded to diacylglycerol (DG; 0.48%). Qualitative analysis of PC antibodies revealed that individuals bitten by ticks were more likely to produce PC-IgG antibodies (p < 0.001). DG levels were significantly higher in tick salivary glands (p < 0.05) compared with tick saliva and salivary fractions. The α-Gal content was higher in tick saliva than in deglycosylated saliva and lipid fractions. These results support a possible role for tick salivary proteins and lipids without α-Gal modifications in AGS.

Evaluation of relative biological effectiveness for diseases of the circulatory system based on microdosimetry.

In the next decade, the International Commission on Radiological Protection (ICRP) will issue the next set of general recommendations, for which evaluation of relative biological effectiveness (RBE) for various types of tissue reactions would be needed. ICRP has recently classified diseases of the circulatory system (DCS) as a tissue reaction, but has not recommended RBE for DCS. We therefore evaluated the mean and uncertainty of RBE for DCS by applying a microdosimetric kinetic model specialized for RBE estimation of tissue reactions. For this purpose, we analyzed several RBE data for DCS determined by past animal experiments and evaluated the radius of the subnuclear domain best fit to each experiment as a single free parameter included in the model. Our analysis suggested that RBE for DCS tends to be lower than that for skin reactions, and their difference was borderline significant due to large variances of the evaluated parameters. We also found that RBE for DCS following mono-energetic neutron irradiation of the human body is much lower than that for skin reactions, particularly at the thermal energy and around 1MeV. This tendency is considered attributable not only to the intrinsic difference of neutron RBE between skin reactions and DCS but also to the difference in the contributions of secondary γ-rays to the total absorbed doses between their target organs. These findings will help determine RBE by ICRP for preventing tissue reactions.

In Situ Ambient Pressure Photoelectron Spectroscopy Study of the Plasma-Surface Interaction on Metal Foils.

The plasma-surface interface has sparked interest due to its potential of creating alternative reaction pathways not available in typical gas-surface reactions. Currently, there are a limited number of in situ studies investigating the plasma-surface interface, restricting the development of its application. Here, we report the use of in situ ambient pressure X-ray photoelectron spectroscopy in tandem with an optical spectrometer to characterize the hydrogen plasma's interaction with metal surfaces. Our results demonstrate the possibility to monitor changes on the metal foil surface in situ in a plasma environment. We observed an intermediate state from the metal oxide to an -OH species during the plasma environment, indicative of reactive hydrogen radicals at room temperature. Furthermore, the formation of metal-carbides in the hydrogen plasma environment was detected, a characteristic absent in gas and vacuum environments. These findings illustrate the significance of performing in situ investigations of the plasma-surface interface to better understand and utilize its ability to create reactive environments at low temperature.

An Unusual Ferryl Intermediate and Its Implications for the Mechanism of Oxacyclization by the Loline-Producing Iron(II)- and 2-Oxoglutarate-Dependent Oxygenase, LolO.

N-Acetylnorloline synthase (LolO) is one of several iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenases that catalyze sequential reactions of different types in the biosynthesis of valuable natural products. LolO hydroxylates C2 of 1-exo-acetamidopyrrolizidine before coupling the C2-bonded oxygen to C7 to form the tricyclic loline core. Each reaction requires cleavage of a C-H bond by an oxoiron(IV) (ferryl) intermediate; however, different carbons are targeted, and the carbon radicals have different fates. Prior studies indicated that the substrate-cofactor disposition (SCD) controls the site of H· abstraction and can affect the reaction outcome. These indications led us to determine whether a change in SCD from the first to the second LolO reaction might contribute to the observed reactivity switch. Whereas the single ferryl complex in the C2 hydroxylation reaction was previously shown to have typical Mössbauer parameters, one of two ferryl complexes to accumulate during the oxacyclization reaction has the highest isomer shift seen to date for such a complex and abstracts H· from C7 ∼ 20 times faster than does the first ferryl complex in its previously reported off-pathway hydroxylation of C7. The detectable hydroxylation of C7 in competition with cyclization by the second ferryl complex is not enhanced in 2H2O solvent, suggesting that the C2 hydroxyl is deprotonated prior to C7-H cleavage. These observations are consistent with the coordination of the C2 oxygen to the ferryl complex, which may reorient its oxo ligand, the substrate, or both to positions more favorable for C7-H cleavage and oxacyclization.

Investigation of Enantioselectivity Using TADDOL Derivatives as Chiral Ligands in Asymmetric Cyanation Reactions.

This study investigates the enantioselectivity challenges of asymmetric cyanation reactions using TADDOL derivatives as chiral ligands, specifically focusing on the cyanosilylation of aldehydes and the cyanation of imines. Despite extensive optimization efforts, the highest achieved ee was only modest, peaking at 71% for the cyanosilylation reaction, while the cyanation of imines consistently resulted in racemic mixtures. Our comprehensive analysis, supported by experimental data and computational modeling, reveals significant barriers to enhancing the enantioselectivity. The results highlight a complex interplay between ligand structure and reaction conditions, demonstrating that even promising ligands such as TADDOL derivatives face substantial challenges in these reaction types. This study underscores the importance of understanding the mechanistic details through computational insights to guide future improvements in asymmetric catalysis.

A national surveillance system for continuous monitoring of blood transfusion safety: German haemovigilance data.

Haemovigilance (HV) systems aim to improve transfusion outcomes in patients and donor safety. An important question for blood regulators is how to ensure an effective HV system. We retrospectively analysed the HV reports submitted to Paul-Ehrlich-Institut over the last two decades. Between 2011 and 2020, 50.86 million units of blood components were used, and 8931 suspected serious donor and recipient adverse reactions (SARs), 874 serious adverse events (SAEs) and 12,073 donor look-backs were reported. Following implementation of specific risk-minimization measures (RMMs) between 2000 and 2010, SAR reporting rates decreased for transfusion-transmitted viral infections (TTVIs), transfusion-related acute lung injury (TRALI) and transfusion-transmitted bacterial infections (TTBIs), while increasing for other serious adverse transfusion reactions. Within this decade, the overall blood component use decreased. Long-term data collection forms the basis to establish trends and changes in reporting and to evaluate the effect of RMM. Standardized criteria for reaction types, seriousness and imputability assessments and availability of a denominator are important elements. Central data collection and independent assessment allow for monitoring HV data in a nationwide context over time. Stakeholder involvement and transparent feedback on the benefit of RMM will help to achieve the objectives of HV.

Site‐Selective Ortho/Ipso C−H Difunctionalizations of Arenes using Thianthrene as a Leaving Group

AbstractSite‐selective ortho/ipso C−H difunctionalizations of aromatic compounds were designed to afford polyfunctionalized arenes including challenging 1,2,3,4‐tetrasubstituted ones (62 examples, up to 97 % yields). To ensure the excellent regioselectivity of the process while keeping high efficiency, an original strategy based on a “C−H thianthenation/Catellani‐type reaction” sequence was developed starting from simple arenes. Non‐prefunctionalized arenes were first regioselectively converted into the corresponding thianthrenium salts. Then, a palladium‐catalyzed, norbornene (NBE)‐mediated process allowed the synthesis of ipso‐olefinated/ortho‐alkylated polyfunctionalized arenes using a thianthrene as a leaving group (revisited Catellani reaction). Pleasingly, using a commercially available norbornene (NBE) and a unique catalytic system, synthetic challenges known for the Catellani reaction with aryl iodides were smoothly and successfully tackled with the “thianthrenium” approach. The protocol was robust (gram‐scale reaction) and was widely applied to the two‐fold functionalization of various arenes including bio‐active compounds. Moreover, a panel of olefins and alkyl halides as coupling partners was suitable. Pleasingly, the “thianthrenium” strategy was successfully further applied to the incorporation of other groups at the ipso (CN/alkyl/H, aryl) and ortho (alkyl, aryl, amine, thiol) positions, showcasing the generality of the process.

Molecular Methods for Detecting Microorganisms in Beverages

Beverages are an integral component of a person’s food package. Various types of microorganisms widely contaminate beverages. This review presents current research data aimed at identifying dominant microorganisms in beverages and molecular methods for their detection. Wine, beer, dairy drinks, and fruit juices were selected as the main objects of the study. The most contaminated beverage turned out to be fruit juice. As a result of a large number of independent studies, about 23 species of microorganisms were identified in it. At the same time, they are represented not only by bacterial and fungal organisms, but also by protozoa. Milk turned out to be the least contaminated in terms of detected bacteria. The most common pollutants of these beverages were Staphylococcus aureus, Bacillus cereus, and Vibrio parahaemolyticus. It has been established that among pathogenic genera, Salmonella sp., Campylobacter sp. and Shigella sp. are often present in beverages. One of the main tools for the quality control of beverages at all stages of their production is different types of polymerase chain reaction. The sequencing method is used to screen for microorganisms in beverages. The range of variations of this technology makes it possible to identify microorganisms in alcoholic and non-alcoholic beverages. The high specificity of methods such as PCR-RFLP, Rep-PCR, qPCR, End-point PCR, qLAMP, the molecular beacon method, and RAPD enables fast and reliable quality control in beverage production. Sequencing allows researchers to evaluate the microbiological diversity of all the studied beverages, while PCR varieties have demonstrated different fields of application. For example, PCR-RFLP, RAPD-PCR, and PCR allowed the identification of microorganisms in fruit juices, qPCR, LAMP, and the molecular beacon method in wine, LAMP and multiplex PCR in milk, and End-point PCR and Rep-PCR in beer. However, it is worth noting that many methods developed for the detection of microbial contaminants in beverages were developed 10–20 years ago; modern modifications of PCR and isothermal amplification are still poorly implemented in this area.

Association between Reactogenicity and Immunogenicity in a Vaccinated Cohort with Two mRNA SARS-CoV-2 Vaccines at a High-Complexity Reference Hospital: A Post Hoc Analysis on Immunology Aspects of a Prospective Cohort Study

Enhancing our comprehension of mRNA vaccines may facilitate the future design of novel vaccines aimed at augmenting immune protection while minimising reactogenic responses. Before this design is carried out, it is important to determine whether adaptive immunity correlates with the reactogenicity profile of vaccines. We studied a large cohort that was vaccinated with mRNA vaccines to answer this question. This was an observational study with real-world data. Reactogenicity data were obtained from the VigilVacCOVID study. Immunogenicity (humoral and cellular) data were retrieved from health records. One main population (n = 215) and two subpopulations were defined (subpopulation 1, n = 3563; subpopulation 2, n = 597). Sensitivity analyses were performed with subpopulations 1 and 2 to explore the consistency of results. We analysed the association of the intensity and types of adverse reactions with the development and quantity of elicited antibody titres. As an exploratory analysis in subpopulation 1, we assessed the association between reactogenicity and cellular immunogenicity. A higher incidence of fever, malaise, and myalgia including severe cases was significantly associated with the development and quantity of positive antibody titres. No significant findings were observed with cellular immunity. We observed a positive association between immunogenicity and reactogenicity. These findings can be relevant for the future development of our understanding of how mRNA vaccines function.

Dimerization of assimilatory NADPH-dependent sulfite reductase reveals elements for diflavin reductase binding at a minimal interface.

Escherichia coli NADPH-dependent assimilatory sulfite reductase is responsible for fixing sulfur for incorporation into sulfur-containing biomolecules. The oxidoreductase is composed of two subunits, an NADPH, FMN, and FAD-binding diflavin reductase and an iron siroheme and Fe4S4-containing oxidase. How they interact has been an unknown for over 50 years because the complex is highly flexible, thus has been intransigent for traditional X-ray or cryo-EM structural analysis. Using a combination of the chameleon plunging system with a fluorinated lipid we overcame the challenge of preserving the minimal dimer between the subunits for high-resolution cryo-EM analysis. Here, we report the first structure of the complex between the reductase and oxidase, revealing how they interact in a minimal interface. Further, we determined the structural elements that discriminate between the pairing of a siroheme-containing oxidase with a diflavin reductase or a ferredoxin partner to channel the six electrons that reduce sulfite to sulfide.

Evaluation of Allergic Reactions and Tolerance with Fruit and Vegetable Allergy in Children

Introduction: Despite the increasing prevalence of fruit and vegetable allergies in childhood over the past decades, the clinical course of reaction types and tolerance remain unclear. Our aim was to evaluate the clinical course, demographic characteristics, and tolerance rate of allergic reactions induced by fruits or vegetables. Methods: We conducted a retrospective, descriptive, cross-sectional study on patients who presented with suspected allergic reactions to fruit or vegetables. We used patient records to identify demographic data, skin prick test, prick-to-prick test, and oral food challenge test results and laboratory findings. Results: The study included 78 children with a median age of 61.5 months. Class 1 and 2 allergies were found in 65 and 13 cases, respectively. The most common allergens were potato (21.8%), banana (15.4%), peach (14.1%), and tomato (12.8%). Clinical symptoms included urticaria (75.6%), oral allergy syndrome (15.4%), angioedema (7.7%), and anaphylaxis (1.3%). Thirteen children achieved tolerance, while 61.7% did not. The median time to tolerance was 13.5 months after diagnosis, with a minimum of 9 months. Significant differences in reaction type, clinical presentation, pan-allergy to aeroallergens, and serum total IgE levels were found between the tolerant and non-tolerant groups (p = 0.006, 0.009, 0.005, and 0.001, respectively). Conclusion: This is the first study to provide guidance on the tolerance rate and resolution time of fruit and vegetable allergies based on demographic and diagnostic parameters. Further research is needed to deepen our understanding of fruit and vegetable allergy.

When TV neighbours become good friends: Understanding Neighbours fans' feelings of grief and loss at the end of the series.

Fans may experience significant upset and distress when a television series ends. However, grief and loss reactions to the end of a fictional series have seldom been investigated. It is likely that the degree to which such reactions are felt is influenced by viewing motives (e.g., pleasure, meaning making), connection to the series and its fan community, relationships formed with characters, including parasocial bonds and experiences of empathy, and tendency to engage with others' perspectives and emotions, including fictional characters. The purpose of this study was to examine predictors of fans' grief and loss reactions to the end of the television series Neighbours, which aired from 1985 to 2022. Fans (n = 1289) completed an online survey shortly after the screening of the final episode. The survey measured grief emotions and cognitions, acceptance that the series had ended, distress at the loss of a parasocial relationship with a favourite character, feelings of closure, and expressions of gratitude for the series. Predictors of these grief and loss reactions examined in the survey were viewing motives, fan identity, strength of a parasocial relationship formed with a favourite character, empathy towards that character, and tendency to take others' perspectives, experience empathic concern and personal distress, and tendency towards engagement with fictional characters. Greater grief and loss reactions were experienced by fans whose motives for watching involved being entertained and exposed to different lifestyles, who felt a stronger fan connection to the series, and who formed stronger parasocial empathic relationships with their favourite character. Factors such as gender, age, and empathic tendencies predicted various types of grief reactions. Understanding fan experiences when a long-running series ends advances theory and research on viewer parasocial relationships and engagement with media, as well as providing evidence that the loss of a series or favourite character can be viewed as a type of grief experience.

Laser-induced oxidation of Cf/SiC composites: Oxidation behavior analysis and parameter optimization

Cf/SiC composite is widely utilized in aerospace and defense sectors owing to their outstanding high-temperature and mechanical performance. However, this material is a typical hard-to-machining material. Building upon prior research on the novel laser-induced oxidation-assisted milling technology, this paper conducted an in-depth study of the oxidation of Cf/SiC composite under laser induction. The study combined thermodynamic analysis with the detection of oxidation products to ascertain the oxidation reaction types of Cf/SiC composite. The oxidation process under the induction of lasers with different energy densities was investigated by combining the oxide layer morphology, element distribution, and high-speed photography results. And the oxidation mechanism was elucidated. A second-order response surface model for the oxide layer thickness with respect to the laser energy density, scanning speed, and scanning path spacing was established, and parameter optimization was performed based on this model. Experimental validation demonstrated the reliability of the model predictions.