Tanjungpura University

The increasing activity of stock investment among millennial investors is increasingly influenced by digital information and behavioral factors. This study aims to examine the effects of social media use, herding bias, and overconfidence on stock investment decisions and to investigate the mediating role of investment intention among millennial investors in West Kalimantan. A quantitative approach was employed involving 200 millennial investors selected through purposive sampling. Data were collected using a Likert-scale questionnaire and analyzed using Structural Equation Modeling–Partial Least Squares (SEM-PLS) with SmartPLS. The findings indicate that social media use and overconfidence have positive and significant effects on stock investment decisions, whereas herding bias has no significant effect. Furthermore, social media use and overconfidence significantly influence investment intention, while herding bias does not have a significant effect. Investment intention mediates the effects of social media use and overconfidence on stock investment decisions but does not mediate the effect of herding bias. These findings suggest that millennial investors stock investment decisions are more strongly associated with exposure to digital information, confidence in their own abilities, and the formation of investment intentions than with the tendency to follow other investors decisions.

Mercury ions (Hg²⁺) are highly toxic environmental pollutants requiring rapid and cost-effective detection methods. This study presents an eco-friendly approach for the green synthesis of silver nanoparticles (AgNPs) using aqueous extracts of nutmeg (Myristica fragrans), pineapple (Ananas comosus), and jambulang (Syzygium cumini), which serve as both reducing and stabilizing agents. The formation of AgNPs was confirmed by UV-Vis spectroscopy, exhibiting characteristic surface plasmon resonance (SPR) peaks around 400 nm, and TEM analysis, which revealed spherical morphology with diameters of 4–6 nm. The synthesized AgNPs were evaluated as colorimetric sensors for Hg²⁺ detection, based on the color change from yellow/brown to colorless due to the Ag-Hg amalgamation process and the subsequent quenching of the SPR peak. Among the three extracts, S. cumini demonstrated superior performance with a limit of detection (LOD) of 0.47 ppm, significantly lower than A. comosus (1.16 ppm) and M. fragrans (2.51 ppm). To demonstrate practical utility, the AgNPs were immobilized onto cotton buds as a portable, “naked-eye” sensor, enabling on-site mercury detection without sophisticated instrumentation. These results suggest that green-synthesized AgNPs offer a sustainable and efficient platform for monitoring heavy metal contamination in aqueous environments.

Smallholder agriculture in Indonesia plays an essential role in sustaining local food production and rural livelihoods. However, management practices remain highly variable and frequently lack adequate environmental safeguards. Groundwater table (GWT) is a primary determinant of peat properties and processes. This study examined soil–environment interactions in Kubu Raya, West Kalimantan, under two dominant smallholder land-use systems: mixed crops (MCR) and pineapple monoculture (PNP). Measurements included key biogeochemical indicators, soil properties, and GWT risk score (SGWT) derived from nationally regulated thresholds (25 cm and 40 cm) and an upper limit of 60 cm. Statistical analysis indicated that GWT exerted a significant influence (p<0.05) on soil moisture and temperature, redox potential, and pH in both systems. However, the strength of these responses differed between land uses. SGWT analysis highlighted distinct hydrological contrasts between sites. The mean GWT at MCR (36.18 cm) lies between the 25- and 40-cm thresholds, whereas PNP (46.44 cm) exceeds both. The result showed that MCR accounted for 31.9% of the risk range above 25 cm (SGWTMCR25 = 0.3194), compared with PNP at 61.3% (SGWTPNP25 = 0.6126). When evaluated against the 40-cm threshold, MCR no longer surpasses the limit (SGWTMCR40 = 0), while PNP remains within 32.2% of the 40–60 cm risk interval (SGWTPNP40 = 0.3220). These hydrological differences correspond to higher estimated CO? emission factors in PNP and greater subsidence risk relative to MCR. The results emphasize the need for site-specific assessment to guide GWT-based peatland management for smallholders.

The kinetics of inactivation of Clostridium sporogenes spores as a surrogate for the sterilization marker Clostridium botulinum using Pulsed Electric Field (PEF) treatment has not been previously investigated. Hence, this study aimed to evaluate and determine the kinetics of C. sporogenes spore inactivation by PEF. The spore suspensions of C. sporogenes were treated using PEF at an electric field intensity of 36 kV/cm with a residence time of 1.302 s. The spore inactivation kinetics were analyzed using several mathematical models, including log-linear, log-linear shoulder, and Weibull models. The electroporation effects were evaluated by measuring the concentration of Ca2+ released into the suspension following PEF treatment. PEF treatment resulted in a reduction of C. sporogenes spores by up to 3.6 log cycles. The inactivation curve of C. sporogenes spores demonstrated a concave downward shape, with a shoulder pattern at the initial time and an exponential decrease as the process time increased. The spore electroporation was evidenced by an increase in Ca2+ concentration in the suspension from 1.58 to 2.03 ppm after PEF treatment. The death rate of C. sporogenes spores (kmax) increased and the shoulder length (S-i) decreased with higher electric field strengths. A concave downward curve of the inactivation curve is shown by a curve shape value (p)> 1. The log-linear shoulder was the best model to describe C. sporogenes spore inactivation. The D-PEF and Z(PEF) values of C. sporogenes spores in the log-linear, log-linear shoulder and Weibull models were in the ranges 2.46-4.222 s and 25-32 kV/cm. These findings demonstrate that PEF can effectively inactivate C. sporogenes spores and that kinetic modeling provides valuable parameters for predicting spore inactivation during PEF processing.

This study employed a bibliometric approach to examine the intellectual structure, emerging themes, and future directions of research on digital technology integration in physical education (PE). Using bibliographic coupling and co-occurrence analyses of 300 publications from Scopus and Web of Science, six intellectual clusters were identified: pedagogical reform, motivation and gamification, immersive technologies, socio-critical perspectives, data-driven practice, and teacher professional development. Thematic evolution reveals growing interest in virtual reality or augmented reality for motor skill acquisition, gamified engagement strategies, data-informed assessment frameworks, and rising attention to equity, ethics, and teacher readiness. Findings indicate a paradigm shift toward systemic and holistic digitalization of PE, where technology is positioned as integral to curriculum, pedagogy, and assessment. The study concludes by proposing interdisciplinary collaboration and mixed-method, longitudinal designs to ensure that digital innovations remain pedagogically meaningful, equitable, and scalable across diverse educational contexts.