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4H silicon carbide (4H‐SiC) holds great promise for high‐power and high‐frequency electronics, in which high‐quality 4H‐SiC wafers with both global and local planarization are cornerstones. Chemical–mechanical polishing (CMP) is the key processing technology in the planarization of 4H‐SiC wafers. Enhancing the performance of CMP is critical to improving the surface quality and reducing the processing cost of 4H‐SiC wafers. In this review, the superior properties of 4H‐SiC and the processing of 4H‐SiC wafers are introduced. The development of CMP with chemical, mechanical, and chemical–mechanical synergistic approaches to improve the performance of CMP is systematically reviewed. The basic principle and processing system of each improvement approach are presented. By comparing the material removal rate of CMP and the surface roughness of CMP‐treated 4H‐SiC wafers, the prospect on the chemical, mechanical, and chemical–mechanical synergistic improvement approaches is finally provided. Recent progress on the CMP of 4H‐SiC wafers are discussed after a brief overview of the basic properties of 4H‐SiC. Chemical, mechanical, and chemical–mechanical synergistic approaches for the efficiency improvement of CMP are highlighted. By discussing the advantages and disadvantages of the efficiency‐improvement approaches, the challenges of using these approaches in industry are analyzed. Finally, prospects on the development of the CMP of 4H‐SiC wafers are presented.

The colloidal silica is used as the abrasive for the copper Chemical Mechanical Polishing slurry in integrated circuit multilayer copper wiring. The aggregation of colloidal silica in the slurries tends to aggregate spontaneously, resulting in the continuous changes of the polishing effect, such as scratch defects, removal rate, etc. This situation can lead to the potential instability of the polishing slurry, which should be avoided in industrial production. In this paper, the aggregation and dispersion properties of polishing slurries were systematically studied, and an scheme was proposed to improve the dispersion of slurries to prevent agglomeration. These affecting factors including slurries’ pH, Potassium nitrate and Sodium Polyacrylate were assessed with Large particle counts, Zeta potential and Particle size. Slurry’s pH at 9.6 had a lower Zeta potential which meant a higher dispersion colloidal silica compared to other pH of slurries. And the dissolution of colloidal silica was verified by UV-vis experiment. Sodium dodecyl sulfate, Dodecyl trimethyl ammonium chloride and Primary Alcobol Ethoxylate-15 were analyzed for their dispersion in slurries from the point of view of static electricity and steric hindrance, and the synergistic mechanism of mixed Sodium dodecyl sulfate and Primary Alcobol Ethoxylate-15 on slurries dispersion was highlighted. In addition, the effect of the improvement of slurry dispersion on reducing scratching defects on the surface of polished copper blanket was also tested in this paper.

Chemical mechanical polishing (CMP) is one of the most important and effective technologies to achieve global planarization for precision machining of the wafer surface. The planarization property of slurry is an essential index in evaluating the quality of the copper (Cu) film CMP process. Prediction of the planarization property is of vital significance for product quality control during the CMP process. Data‐driven approaches to predict results based on response surface methodology (RSM) and neural network (NN) to pursue better prediction performance were proposed in this paper. In our design, all three optimization methods (RSM, NN, RSM + NN) are proved to be accurate and reliable, which can predict the experimental results with finer grid accuracy under the condition of only 17 test data points. In particular, the prediction accuracy of RSM + NN method is higher than that of the other two methods, and the error is only 0.16 %. Notably, the results demonstrate that such less time‐consuming optimization methods can realize the acquisition of more desirable CMP process parameters and compositions of slurries, and the versatility and simplicity of our methods can also potentially provide an alternative experiment design concept for a wider range of applications. A reasonable predictive optimization method (the combination of RSM and NN) with error of only 0.16 % could be obtained under the condition of only 17 test data points. This research paves a new way to optimize CMP process parameters and compositions of slurries, and this time‐saving method is also expected to be applied in other areas.

Background/Objectives: Caffeine is widely recognized as an ergogenic aid, yet evidence regarding its acute effects on repeated sprint ability (RSA) remains inconsistent. This systematic review and meta-analysis aimed to evaluate the effects of acute caffeine ingestion on RSA across different populations, exercise modalities, and dosage levels. Methods: A comprehensive literature search was conducted in the PubMed, EBSCO, Cochrane Library, Web of science, and Scopus databases. Data were pooled using the weighted mean difference (WMD) with 95% confidence interval (CI). Results: Thirteen studies met the inclusion criteria. Acute caffeine ingestion significantly enhanced RSA peak power output (PPO) compared with placebo (WMD, 5.28; 95% CI, 2.49 to 8.07; p = 0.0002). Subgroup analyses revealed significant improvements in both males (WMD, 13.11; 95% CI, 5.63 to 20.59; p = 0.0006) and females (WMD, 4.03; 95% CI, 1.10 to 6.97; p = 0.007). A caffeine dose of ≥6 mg/kg body weight (BW) produced greater ergogenic benefits (WMD, 6.67; 95% CI, 3.32 to 10.02; p < 0.0001) than lower doses (WMD, 2.16; 95% CI, −2.87 to 7.19; p = 0.40). Moreover, a more pronounced enhancement was observed in cycling-based RSA (WMD, 8.77; 95% CI, 1.98 to 15.56; p = 0.01) compared with running-based protocols (WMD, 4.56; 95% CI, 1.58 to 7.55; p = 0.003). Conclusions: Acute caffeine ingestion significantly enhances RSA, particularly at doses ≥6 mg/kg BW. This effect is consistent across both male and female participants, with no statistically significant sex difference observed in the pooled analysis. These findings reinforce caffeine’s role as an effective ergogenic aid for optimizing high-intensity intermittent performance, with the strongest benefits evident in cycling exercise.

AISI 321 stainless steel has excellent resistance to intergranular corrosion and is generally used in nuclear power reactor vessels and other components. The as-cast and wrought structures are quite different in hot workability, so physical simulation, electron back-scatter diffraction, and hot processing maps were used to study the mechanical behavior and microstructure evolution of as-cast nuclear grade 321 stainless steel in the temperature range of 900–1200 °C and strain rate range of 0.01–10 s−1. The results showed that the flow curve presented work-hardening characteristics. The activation energy was calculated as 478 kJ/mol. The fraction of dynamic recrystallization (DRX) increased with increasing deformation temperature and decreasing strain rate. DRX grain size decreased with increasing Z value. Combining the hot working map and DRX state map, the suggested hot working window was 1000–1200 °C and 0.01–0.1 s−1. The main form of instability was necklace DRX. The nucleation mechanism of DRX was the migration of subgrains. The δ phase reduced the activation energy and promoted DRX nucleation of the tested steel.

18Mn18Cr0.6N steel was tension tested at 0.001 s−1 to fracture from 1473 K to 1363 K (1200 °C to 1090 °C, fracture temperature) at a cooling rate of 0.4 Ks−1. For comparison, specimens were tension tested at temperatures of 1473 K and 1363 K (1200 °C and 1090 °C). The microstructure near the fracture surface was examined using electron backscatter diffraction analysis. The lowest hot ductility was observed under continuous cooling and was attributed to the suppression of dynamic recrystallization nucleation.

Lipids play an important role in coordinating and regulating metabolic and inflammatory processes. Sprint interval training (SIT) is widely used to improve sports performance and health outcomes, but the current understanding of SIT-induced lipid metabolism and the corresponding systemic inflammatory status modification remains controversial and limited, especially in male adolescents. To answer these questions, twelve untrained male adolescents were recruited and underwent 6 weeks of SIT. The pre- and post-training testing included analyses of peak oxygen consumption (VO2peak), biometric data (weight and body composition), serum biochemical parameters (fasting blood glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triacylglycerol, testosterone, and cortisol), inflammatory markers, and targeted lipidomics. After the 6-week SIT, the serum C-reactive protein (CRP), interleukin (IL)-1β, IL-2, IL-4, IL-10, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β significantly decreased (p < 0.05), whereas IL-6 and IL-10/TNF-α significantly increased (p < 0.05). In addition, the targeted lipidomics revealed changes in 296 lipids, of which 33 changed significantly (p < 0.05, fold change > 1.2 or <1/1.2). The correlation analysis revealed that the changes in the inflammatory markers were closely correlated with the changes in some of the lipids, such as LPC, HexCer, and FFA. In conclusion, the 6-week SIT induced significant changes in the inflammatory markers and circulating lipid composition, offering health benefits to the population.

The dynamic recrystallization and hot-ductility behaviors in fine- and coarse-grained 18Mn18Cr0.5N steel were determined between 1273 K and 1473 K (1000 °C and 1200 °C) at a strain rate of 0.1 s −1 through compression and tensile tests. The microstructure was examined using optical microscopy, electron backscatter diffraction analysis, and transmission electron microscopy. The fracture morphology was observed using scanning electron microscopy. The coarse initial grain size delays the initiation and development of dynamic recrystallization and then results in a lower hot ductility. The nucleation of dynamic recrystallization grains at triple junctions and at grain boundaries is mainly accompanied by the evolution of twinning and low-angle grain boundaries, respectively. The nucleation mechanism of dynamic recrystallization grains affects the dynamic recrystallization grain size. Dynamic recrystallization grains evolved by the necklace mechanism are coarser than those evolved by the ordinary mechanism. The hot ductility of 18Mn18Cr0.5N steel is very sensitive to grain size, particularly at lower temperatures. The fine-grained material can tolerate higher damage before fracture. Finally, the optimized hot-working process was determined.

Introduction Sleep disturbance among students has become a growing concern because of its adverse effects on cognitive function, mental health, and quality of life. Previous research showed that University students report significantly poorer sleep hygiene compared to the general population (Hershner, 2020).1 However, the sleep hygiene and quality of UK university students remain unclear. Here, we explore the specific behavioural factors associated with poor sleep among University students in the UK.MethodsA cross-sectional survey design was employed to collect data from university students, including questions regarding sleep patterns, sleep quality, and sleep hygiene. Participants were recruited through University societies, and data were analyzed using descriptive statistics, unsupervised machine learning and regression analysis.ResultsOur data included 892 students, (71.4% female, 24.3% male and 4.3% other), mainly from the Universities of Leicester (68.5%) and Cambridge (12.9%). Most students (60.4%), aged between 18 and 21 years old, slept for an average of 8.08 (s.d. = 2.1) hours and reported a tiredness score of 6.24 (s.d. = 1.71). We found that the sleep hygiene index was significantly correlated with self-reported tiredness (𝛽 =0.09, s.e. = 0.02, P < 0.0001), while accounting for covariates. We then used unsupervised learning to identify the main features of sleep hygiene linked to poor sleep, and found that irregular sleep patterns were the main features of poor sleep. The second most important component of poor sleep hygiene in this cohort was linked to stress.DiscussionOur results highlight the importance of providing guidance on regular sleep schedules and stress related interventions for students. We are currently evaluating the effectiveness of interventions targeting these behavioural factors to improve sleep outcomes in the student population.ReferenceHershner S. Sleep and academic performance: Measuring the impact of sleep. Current Opinion in Behavioral Sciences, 2020;33:51–56.

An 8% Cr cold roller steel was compressed in the temperature range 900–1200 °C and strain rate range 0.01–10 s −1 . The mechanical behavior has been characterized using stress–strain curve analysis, kinetic analysis, processing maps, etc. Metallographic investigation was performed to evaluate the microstructure evolution and the mechanism of flow instability. It was found that the work hardening rate and flow stress decreased with increasing deformation temperature and decreasing strain rate in 8% Cr steel; the efficiency of power dissipation decreased with increasing Z value; flow instability was observed at higher Z -value conditions and manifested as flow localization near the grain boundary. The hot deformation equation and the dependences of critical stress for dynamic recrystallization and dynamic recrystallization grain size on Z value were obtained. The suggested processing window is in the temperature range 1050–1200 °C and strain rate range 0.1–1 s −1 in the hot processing of 8% Cr steel.