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Lightweight and high-strength insulation materials have important application prospects in the aerospace, metallurgical, and nuclear industries. In this study, a highly porous silica fiber reinforced phenolic resin matrix composite was prepared by vacuum impregnation and atmospheric drying using quartz fiber needled felt as reinforcement and anhydrous ethanol as a pore-making agent. The effects of curing agent content on the structure, composition, density, and thermal conductivity of the composite were studied. The mechanical properties of the composite in the xy direction and z direction were analyzed. The results showed that this process can also produce porous phenolic resin (PR) with a density as low as 0.291 g/cm3, where spherical phenolic resin particles are interconnected to form a porous network structure with a particle size of about 5.43 μm. The fiber-reinforced porous PR had low density (0.372~0.397 g/cm3) and low thermal conductivity (0.085~0.095 W/m·K). The spherical phenolic resin particles inside the composite were well combined with the fiber at the interface and uniformly distributed in the fiber lap network. The composite possessed enhanced mechanical properties with compressive strength of 3.5–5.1 MPa in the xy direction and appeared as gradual compaction rather than destruction as the strain reached 30% in the z direction. This research provides a lightweight and high-strength insulation material with a simple preparation process and excellent performance.

Inclusions are one of the important factors affecting the cleanliness of molten steel. The current optimization of inclusion removal methods mainly focuses on promoting inclusions to float to the slag–steel interface so that the inclusions can be absorbed and removed by the refining slag. However, the research on the floating removal of inclusions cannot be carried out directly in the ladle, so methods such as mathematical models and physical models were developed. This article uses silicone oil to simulate the slag layer; polypropylene particles; and aluminum oxide particles to simulate inclusions to establish a water model experiment. By changing the viscosity of silicone oil and the diameter of particles, the factors affecting the movement of inclusions at the slag–steel interface were explored. Based on the water model, a mathematical model of the floating behavior of inclusions at the slag–steel interface was constructed, and parameters such as particle diameter and interfacial tension in the water model experiment were studied by the mathematical model for calculation. Both the mathematical model and the water model experimental results show that after the viscosity of silicone oil increases from 0.048 Pa·s to 0.096 Pa·s, the dimensionless displacement and terminal velocity of the particles decreases. When the diameter of the same particle increases, the dimensionless displacement and terminal velocity increases. The dimensionless displacement of polypropylene particles of the same diameter is larger than that of aluminum oxide particles, and the terminal velocity is smaller than that of aluminum oxide particles. This is attributed to the better overall three-phase wettability of polypropylene particle. When the liquid level increases, the dimensionless displacement and terminal velocity of particles under the same conditions show only slight differences (less than 10%).

In previous research simulating steelmaking ladles using cold water models, the dosage/volume of the salt tracer solution is one of the factors that has been overlooked by researchers to a certain extent. Previous studies have demonstrated that salt tracers may influence the flow and measured mixing time of fluids in water models. Based on a water model scaled down from an industrial 130-ton ladle by a ratio of 1:3, this study investigates the impact of salt tracer dosage on the transport and mixing of tracers in the water model of gas-stirred ladle with a moderate gas flow rate. A preliminary uncertainty analysis of the experimental mixing time is performed, and the standard deviations were found to be less than 15%. It was observed in the experiments that the transport paths of tracers in the ladle can be classified into two trends. A common trend is that the injected salt solution tracer is asymmetrically transported towards the left sidewall of the ladle by the main circulation. In another trend, the injected salt solution tracer is transported both by the main circulation to the left side wall and by downward flow towards the gas column. The downward flow may be accelerated and become a major flow pattern when the tracer volume increases. For the dimensionless concentration curve, the sinusoidal type, which represents a rapid mixing, is observed at the top surface monitoring points, while the parabolic type is observed at the bottom monitoring points. An exception is the monitoring point at the right-side bottom (close to the asymmetric gas nozzle area), where both sinusoidal-type and parabolic-type curves are observed. Regarding the effect of tracer volume on the curve and mixing time, the curves at the top surface monitoring points are less influenced but curves at the bottom monitoring points are noticeably influenced by the tracer volume. A trend of decreasing and then increasing as the tracer volume increases was found at the top surface monitoring points, while the mixing times at the bottom monitoring points decrease with the increase in the tracer volume.

Mathematics teachers' teaching beliefs play an important role in instructional practices and students' achievement. In China, transmissive teaching beliefs were prevalent before 2001. Since then, a student-centered concept has been advocated in the national curriculum reform; however, few studies have assessed contemporary Chinese mathematics teachers' teaching beliefs during the 20 years since the reform. In the current study, we elucidated the teaching beliefs Chinese teachers hold and their effects on instructional practices and students' mathematics achievement. A total of 1463 mathematics teachers and 12,437 students in grade 4 were recruited from Beijing, Shanghai, Jiangsu, and Zhejiang in Eastern China. Based on self-reported teaching beliefs using a short revised version of the Teacher Education and Development Study in Mathematics (TEDS-M), the study identified that contemporary Chinese teachers usually hold constructive teaching beliefs. In comparison, transmissive teaching beliefs showed significantly higher scores for teachers with more than 20 years of teaching experience. Moreover, male teachers and those with more teaching experience were more transmissive, but the effect of gender was small. The indirect effect of teachers' teaching beliefs on students' mathematics achievement through perceived constructive instructional practices was revealed using a multilevel structural equation model. This study illustrates the teaching beliefs of Chinese mathematics teachers and their effects, using evidence collected from a more general perspective.

Abstract Background In this study, relationships between clinicopathologic characteristics and progression‐free survival (PFS) of patients after thymomectomy were analyzed to provide valuable suggestions regarding the treatment of thymoma. Methods Data from 187 thymoma patients undergoing surgery at Beijing Tongren Hospital between January 1, 2006, and December 31, 2015, were retrospectively reviewed. We explored the risk factors for PFS among sex, age, thymoma‐associated MG, completeness of resection, histologic type and TNM stage, and investigated their interrelationship. Results Among the 187 patients, 18 patients (9.63%) had tumor recurrence/metastasis, and all of whom had in situ recurrence or pleural metastasis, and most of them (10 of 18 patients) had MG symptoms that reappeared or were aggravated. Fifteen patients (8.02%) died, and myasthenic crisis was a leading cause. Based on Cox regression analysis, only age (HR = 3.16; 95% CI: 1.44–6.91; p = 0.004) and the completeness of resection (HR = 9.03; 95% CI: 2.58–31.55; p = 0.001) were independent risk factors for PFS. Furthermore, we found that the completeness of resection was related to the histologic type (p = 0.009) and TNM stage (p

Abstract Background Optimization of risk stratification is important for facilitating prognoses and therapeutic decisions regarding diffuse large B‐cell lymphoma (DLBCL). However, a simple and applicable prognostic tool is lacking for individuals with human immunodeficiency virus (HIV)‐related DLBCL in the era of combined antiretroviral therapy (cART). Methods This retrospective multicenter observational study included 147 HIV‐related DLBCL patients with histologically confirmed DLBCL from 2013 to 2020. The total group was divided into training (n = 78) and validation (n = 69) cohorts to derive the best prognostic score. Clinicopathological and characteristic biomarkers correlated with clinical outcomes were analyzed. Results Age, Ann Arbor stage, lactate dehydrogenase (LDH) ratio, bulky disease, and red blood cell distribution width (RDW) ratio retained robust independent correlations with overall survival (OS) in multivariate analysis. A new and practical prognostic model was generated and externally validated, classifying patients into three categories with significantly different survival rates. Moreover, the new index outperformed the International Prognostic Index (IPI) score (area under the curve values of 0.94 vs. 0.81 in the training cohort and 0.85 vs. 0.74 in the validation cohort, C‐indices of 0.80 vs. 0.70 in the training cohort and 0.74 vs. 0.70 in the validation cohort, and integrated discrimination improvement values of 0.203 in the training cohort and 0.175 in the validation cohort) and was better at defining intermediate‐ and high‐risk groups. The calibration curves performed satisfactorily for predicting 3‐year OS in the training and validation cohorts. Conclusions We developed and validated a simple and feasible prognostic model for patients with HIV‐related DLBCL that had more discriminative and predictive accuracy than the IPI score for risk stratification and individualized treatment in the cART era.

Abstract Chorus waves are naturally occurring electromagnetic emissions in space and are known to produce highly energetic electrons in the hazardous radiation belt. The characteristic feature of chorus is its fast frequency chirping, whose mechanism remains a long-standing problem. While many theories agree on its nonlinear nature, they differ on whether or how the background magnetic field inhomogeneity plays a key role. Here, using observations of chorus at Mars and Earth, we report direct evidence showing that the chorus chirping rate is consistently related to the background magnetic field inhomogeneity, despite orders of magnitude difference in a key parameter quantifying the inhomogeneity at the two planets. Our results show an extreme test of a recently proposed chorus generation model and confirm the connection between the chirping rate and magnetic field inhomogeneity, opening the door to controlled plasma wave excitation in the laboratory and space.

Abstract The inter-individual variations of gut microbiome contribute to the different responses toward drug therapy among populations, developing a reliable ex vivo culture method for mixed bacteria is the urgent need for predicting personal reaction to drug therapy. Unfortunately, very few attentions have been paid to the bias that could be introduced during the culture process for mixed bacteria. Here we systemically evaluated the factors that may affect the outcomes of cultured bacteria from human feces. We demonstrated that inter-individual difference of host gut microbiome was the main factor affecting the outcomes of cultured bacteria, followed by the culture medium and time point. We further optimized a new medium termed GB based on our established multi-dimensional evaluation method, which could mimic the status of in situ host gut microbiome to the highest extent. Finally, we assessed the inter-individual metabolism by host gut microbiome from 10 donors on three frequently used clinical drugs (aspirin, levodopa and doxifluridine) based on the optimized GB medium. Our results revealed obvious variation in drug metabolism by microbiome from different donors, especially levodopa and doxifluridine. This work suggested the optimized culture medium had the potential for exploring the inter-individual impacts of host gut microbiome on drug metabolism.

Abstract Whistler mode chorus waves frequently appear as discrete, repetitive, and quasi‐monochromatic emissions with frequency chirping. With different wave amplitude and frequency chirping rate, chorus waves have been observed not only in the magnetosphere of the Earth but also in the magnetospheres of other planets, such as Saturn and Jupiter. Motivated by understanding different properties of chorus waves at these planets using the recently proposed “Trap‐Release‐Amplify” (TaRA) model, we perform a parametric study using Particle‐In‐Cell simulations by varying background magnetic field inhomogeneity and the corresponding threshold hot electron number density. We show the consistency between simulation results and theoretical predictions for threshold hot electron number density, chorus chirping rate, and wave amplitude. Our results suggest the significant role of the background magnetic field inhomogeneity in affecting chorus wave properties, including its amplitude at different planets as predicted by the TaRA model.

ABSTRACTObjectives To observe the protective effects of dexmedetomidine (Dex) postconditioning on myocardial ischemia/reperfusion injury (IRI) and to explore its potential molecular mechanisms.Methods One-hundred forty-seven male Sprague-Dawley rats were randomly divided into five groups receiving the different treatments: Sham, ischemia/reperfusion (I/R), Dex, Brusatol, Dex + Brusatol. By the in vivo rat model of myocardial IRI, cardioprotective effects of Dex postconditioning were evaluated by assessing serum CK-MB and cTnI levels, myocardial HE and Tunel staining and infarct size. Furthermore, the oxidative stress-related markers including intracellular ROS level, myocardial tissue MDA level, SOD and GSH-PX activities were determined.Results Dex postconditioning significantly alleviated myocardial IRI, decreased intracellular ROS and myocardial tissue MDA level, increased SOD and GSH-PX activities. Dex postconditioning significantly up-regulated myocardial expression of Bcl-2, down-regulated Bax and cleaved caspase-3 and decreased cardiomyocyte apoptosis rate. furthermores, Dex postconditioning promoted Nrf2 nuclear translocation, increased myocardial expression of Sirt3 and SOD2 and decreased Ac-SOD2. However, brusatol reversed cardioprotective benefits of Dex postconditioning, significantly decreased Dex-induced Nrf2 nuclear translocation and reduced myocardial expression of Sirt3 and SOD2.Conclusions Dex postconditioning can alleviate myocardial IRI by suppressing oxidative stress and apoptosis, and these beneficial effects are at least partly mediated by activating the Nrf2/Sirt3/SOD2 signaling pathway.

Learning progressions can reflect students' continuous in-depth thinking development paths, and their establishment is an iterative process from the construction of hypothetical learning progressions to the verification of that hypotheses. Considering the limitations of the existing verification method of learning progressions based on a rule space model, this study put forward a new validating method based on the hierarchical diagnostic classification model (HDCM) and developed a learning progression with grade 5 students' fraction operations as an example. An expert group first abstracted the attributes and then developed a hypothesized learning progression. Next, the HDCM was used to analyze the test data collected from 817 fifth-grade students, followed by the revision of the learning progression hypothesis. Results showed that (1) the fractional operations involved five attributes: basic operation (A1), reduction of a fraction (A2), changing fractions to a common denominator (A3), split with mix number (A4), and borrowing (A5); (2) the constructed learning progression featured four levels: Level 1 with A1, Level 2 with both A1 and A2, Level 3 with the first four attributes, and Level 4 with all five attributes.

Countries across the world have seen a growing gap in mathematics performance between low-SES children and those from wealthier backgrounds. The issue of inequality not only relates to student performance, but also to schooling--as defined by the mathematics curriculum and its distribution of the related opportunities to learn. Whether relationships between student background, schooling (curriculum coverage), and performance varies between countries with different levels of development has become a question of particular interest to countries and their curriculum-related policies. Those same countries want to achieve both international recognition for excellence as well as equality. Relatedly, the policy question that has arisen is whether both excellence and equality can be achieved simultaneously. The answers to both questions are complex as the relationships between the three key concepts vary among the 63 PISA countries by substantial amounts. Additionally, the averages between the three types of countries vary as well. This all leads to the conclusion that the probability of achieving both excellence and equality varies by the wealth of the country.

The upgrade educational information technology triggered by COVID-19 has shaped a new educational order and new educational forms. As a result, traditional educational measurement is now facing a systematic transformation, that is, from the Assessment of Learning (AoL) to Assessment for Learning (AfL), and finally to Assessment as Learning (AaL). By showing the initiative and the flexibility of large-scale online learning during the COVID-19 pandemic, this paper examines the evolution from AoL to AaL from four aspects: participants, test form, multivariate data for process-based measurement, and measurement models for multivariate data. We propose multidisciplinary corporations in the field, which integrate education, psychology, and information technology into the theories and methods of educational measurement. Further, we emphasize that the validity, ethics, and fairness of the measurement should also be considered the critical issues. Researchers and practitioners of educational measurement must persist in pursuing the substantive significance of measurement and provide unique experience and guidance for the theoretical and practical development of educational assessment in this great revolution.

Studies have rarely investigated the association between extrinsic motivation and social media fatigue. This study aims to examine the mediating role of Fear of missing out (FOMO) and problematic social media use in the association between extrinsic academic motivation and social media fatigue. A total of 399 college students (43% males) completed measures of extrinsic academic motivation, FOMO, problematic social media use, and social media fatigue. The results showed that FOMO mediated the relationship between extrinsic academic motivation and problematic social media use; problematic social media use mediated the association between FOMO and social media fatigue; extrinsic academic motivation fostered social media fatigue either through FOMO or problematic social media use, or through these two factors together; and the indirect mediation effects between extrinsic academic motivation and social media fatigue through problematic social media use were larger than the single mediation effect of FOMO and their serial mediation effects. In addition, the indirect effects of the three subconstructs of extrinsic academic motivation (external regulation, introjected regulation, and identified regulation) on social media fatigue follow a trend of gradual decline. The findings and implications of this study are presented and discussed., Author(s): Yanni Shen [sup.1] , Shiyi Zhang [sup.1] , Tao Xin [sup.1] Author Affiliations: (1) grid.20513.35, 0000 0004 1789 9964, Collaborative Innovation Center of Assessment toward Basic Education Quality, Beijing [...]