Rajamangala University of Technology Rattanakosin

This study presents the development of a bio-based flame retardant derived from renewable soybean oil to improve the flame retardant performance of poly (lactic acid) (PLA). Soybean oil phosphate ester (SOPE) was synthesized from epoxidized soybean oil (ESO) and incorporated into PLA at loadings of 0.5–2 phr via twin-screw extrusion. FT-IR and NMR analyses confirmed the successful synthesis of SOPE. Thermal analysis revealed that the incorporation of SOPE influenced the thermal degradation behavior and crystallization properties of PLA. PLA containing 2 phr SOPE achieved a limiting oxygen index (LOI) value of 26% and attained a V-0 rating in the UL-94 vertical burning test, indicating effective flame retardancy at a low loading level. TGA results showed a relatively low char yield, suggesting that the flame retardant mechanism did not predominantly occur in the condensed phase. Py-GC/MS analysis detected phosphorus-containing radical species (PO• and PO 2 •), indicating that the flame retardant action mainly proceeded via a gas-phase radical trapping mechanism. However, the incorporation of SOPE led to a reduction in molecular weight and mechanical properties due to the hydrolytic degradation of PLA. Overall, the results demonstrate that soybean oil–derived phosphate ester can serve as a bio-based and effective flame retardant for PLA.

School bullying has been recognized as a risk factor for the growth of malevolent creativity. However, its underlying mechanisms and moderators remain under-explored. This study examined the effects of school bullying on malevolent creativity, focusing on the chain mediating effects of anger and hostile attribution bias. Using convenience sampling, we surveyed 1,038 middle school students with the Delaware Bullying Victimization Scale, the Anger Rumination Scale, the Hostile Attribution Bias Scale, and the Malevolent Creativity Scale. A Chain mediation model was estimated in Mplus written by Bengt Muthén and Linda Muthén of the University of California, Los Angeles. Results showed that school bullying significantly is positively associated with malevolent creativity (β = 0.525, p < 0.001, 95% CI=[0.492,1.016]). Besides, school bullying also indirectly was associated with malevolent creativity through anger (β = 0.017, p < 0.001, CI=[0.037, 0.231]), hostile attribution bias (β = 0.318, p < 0.001, CI=[0.042, 0.135]), and the chain-mediated pathway between the above two (β = 0.135, p < 0.001, [0.002,0.009]). These findings indicate that, among victimized adolescents, anger and hostile attribution bias amplify the positive association between school bullying and malevolent creativity. These findings suggest that anger and hostile attribution bias play crucial roles in the relationship between school bullying and malevolent creativity, providing important insights for interventions.

This study provides a comprehensive overview of research on language education (2000–2024), aiming to observe the development trends, describe collaborations among authors, institutions, countries, and disciplines, and map the knowledge landscape. Additionally, the study interprets research hotspots and outlines future directions in the field of language education. The research collected 3,326 scientific publications from the Web of Science Core Collection (WoSCC) and employed bibliometric analysis to interpret the data. Tools such as CiteSpace, HisCite, the Alluvial Generator, and R were used to visualize knowledge maps of language education. The findings indicate a sustained growth trend in language education research and identify key contributors, highlighting the significant achievements of scholars and institutions from North America, and China. The study also presents the leading journals, articles, and disciplines contributing to language education research. Furthermore, it identifies current research focus areas, including positive psychology in language learning, English as a second language teaching, translanguaging, machine translation, and AI-assisted language learning, especially the roles of VR, AR, and chatbots. The study emphasizes the growing importance of technology in language learning and predicts an increasing integration of various technological tools in future language education research.

This study investigates the effect of altitude on 5G signal quality using real-world drive tests conducted along the Borommaratchachonnani Elevated Road in Bangkok, Thailand. Two major mobile network operators (MNO-01 and MNO-02) were evaluated under four driving scenarios across elevated and ground routes. Three essential indicators Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), and Signal-to-Noise Ratio (SNR) were collected through the G-NetTrack Pro application. Results show that RSRP was stronger on elevated roads (−68.66 dBm for MNO-01 and −70.87 dBm for MNO-02), while RSRQ and SNR were better at ground level, indicating more stable connections despite slightly weaker signal strength. Statistical analysis confirmed significant differences (p < 0.001) between altitudes and operators. Furthermore, MNO-01, operating entirely in Standalone (SA) mode, achieved continuous 5G connectivity, whereas MNO-02 (Non-Standalone, NSA) experienced LTE fallback on 15.48% of elevated segments. These findings highlight how altitude and network architecture jointly affect 5G signal strength, quality, and stability.

This paper presents a Single-Phase Induction Motor (SPIM) driven by a Single-Phase Matrix Converter (SPMC). The proposed converter directly transforms a fixed-amplitude, fixed-frequency AC supply into an AC output with adjustable amplitude and frequency at the load, utilizing four bi-directional switches. Sinusoidal Pulse Width Modulation (SPWM) signals are employed to control the switches, with modulation indexes and output frequencies regulated according to the V/f control method for efficient operation of the SPIM. The motor’s torque and speed responses are evaluated through simulations conducted in the MATLAB/Simulink program to verify the system’s performance.

Abstract Purpose – This study investigates the direct and indirect relationships between social isolation and social media addiction among Chinese university students, with social anxiety and fear of missing out (FoMO) as serial mediators in the digital era. Design/methodology – Data were collected from 210 students across seven universities in different cities and academic majors using random sampling. Hypotheses were tested in SPSS and SmartPLS through four stages: (1) descriptive analysis, (2) confirmatory factor analysis, (3) structural model evaluation, and (4) mediation testing (direct, simple, and serial). Findings – Social isolation was positively associated with social media addiction, social anxiety, and FoMO. Social anxiety further increased FoMO and social media addiction, while FoMO also amplified social media addiction. Mediation analyses showed that social isolation indirectly predicted social media addiction via social anxiety (indirect effect = 0.121***), FoMO (indirect effect = 0.104***), and their sequential pathway (specific indirect effect = 0.161***). Descriptively, 60% of students (n = 126) reported above-average levels of social isolation, and 76.19% (n = 160) scored ≥ 19 on the Bergen Social Media Addiction Scale, indicating moderate to high addiction levels. Originality/value – By applying a tripartite theoretical framework, this study extends Sociometer Theory and identifies a novel intra-psychological mechanism linking social isolation to social media addiction. Importantly, recognizing these antecedent factors enables early detection and prevention, thereby reducing the prevalence and harms of social media addiction among university students.