Jenderal Soedirman University

This study provides computational insights into the flexural strengthening of reinforced concrete (RC) T-beams in the negative moment region using steel-reinforced polymer cement mortar (PCM) overlays. A validated three-dimensional nonlinear finite element (FE) model was developed using the Advanced Tool for Engineering Nonlinear Analysis (ATENA) software (version 2023.0.0.22492) to simulate the behavior of beams retrofitted with 40 mm thick PCM layers embedded with 13 mm and 16 mm deformed bars. Model validation was performed against previously published experimental results reported by the authors, demonstrating excellent agreement, with normalized mean square error (NMSE) values expressed as fractions between 0.0001 and 0.0022, and experimental-to-numerical ultimate load ratios ranging from 0.99 to 1.01. Parametric analyses were then conducted to investigate the influence of key variables, concrete compressive strength, PCM overlay thickness, and longitudinal reinforcement ratio on the global flexural performance. The results revealed that increasing the overlay thickness raised the ultimate load capacity by up to 15.4% and improved energy absorption by 43%. Enhancing concrete strength led to gains of up to 12.5% in load capacity and 15.8% in stiffness. Variations in reinforcement ratio had the most significant impact, increasing peak load by up to a factor of 2.02 and improving energy absorption by up to a factor of 1.49. Despite these improvements, reductions in ductility were observed across all strengthening configurations, underscoring a strength-deformability trade-off critical for seismic applications. These findings affirm the efficacy of steel-reinforced PCM overlays and provide design-oriented insights for optimizing negative moment retrofitting strategies in RC bridge girders and continuous beam systems.

The strengthening of reinforced concrete (RC) beams requires repair systems that can enhance strength, stiffness, and energy dissipation without significantly increasing self-weight or compromising durability. This study explores the structural response of RC beams strengthened using an integrated shear-flexure system combining near-surface-mounted carbon fiber-reinforced polymer (NSM-CFRP) ropes and steel-reinforced geopolymer overlays in the compression zone. Monotonic three-point bending tests were performed on two RC beam specimens, one unstrengthened control and one strengthened beam, to obtain preliminary observations of load-deflection behavior, stiffness, ductility, and energy absorption. The strengthened specimen exhibited increases in ultimate load (28.6%), stiffness (13.6%), and energy absorption (7.65%) relative to the control beam, suggesting the potential for effective composite action between the CFRP ropes and geopolymer material. A three-dimensional nonlinear finite element model was developed using ATENA to support interpretation of the experimental response, incorporating detailed constitutive models for concrete, steel reinforcement, and CFRP ropes. The numerical predictions showed reasonable agreement with the experimental results. Within the limitations of the test matrix, the results indicate that the proposed dual strengthening system may offer a viable and sustainable approach for enhancing the shear-flexural performance of RC beams.

Sea surface clorophyll-a (SSC) represents a fundamental indicator of oceanic primary production and serves as a widely used proxy for phytoplankton biomass. Although upwelling is recognised as the dominant driver of SSC variability, precipitation and river discharge can substantially modulate its spatial and temporal distribution. This study examines the spatiotemporal dynamics of SSC in the Arafura Sea, utilising satellitederived oceanographic data from 1998 to 2022, with a focus on the influences of upwelling, precipitation, and oceanographic conditions. Seasonal analysis reveals that SSC peaks during the SE monsoon (June-August), coinciding with intensified upwelling, as indicated by positive Ekman pumping velocity (EPV), reduced sea surface height, and lowered sea surface temperature (SST). Coastal regions consistently exhibit higher SSC, driven by riverine discharge and precipitation-enhanced nutrient input. Regional correlation analysis confirms that offshore EPV and increased precipitation are the dominant mechanisms driving SSC enhancement during the SE monsoon. Climatological correlation analysis further identifies a strong positive relationship between SSC and EPV in key regions, with a maximum correlation coefficient of 0.85. The spatial distribution of SSC exhibits a pronounced inshore-offshore gradient across both monsoon seasons, reflecting the interplay between coastal upwelling, stable river discharge, and nutrient runoff. The empirical orthogonal function analysis of interannual variability suggests that SSC fluctuations are influenced by additional drivers beyond the El-Nino Southern Oscillation, including SST co-variability and anomalous precipitation patterns over central and north-western Papua. These findings show that phytoplankton variability in the Arafura Sea is chiefly controlled by local ocean, atmosphere, and land interactions, underscoring their importance for ecosystem forecasting.

This study aims to investigate the asymmetric effects of changes in international prices of energy and food and the monetary variables, including exchange rates and policy interest rates, on consumer price index (CPI) inflation in Indonesia. This study employs the Nonlinear Autoregressive Distributed Lag (NARDL) model for the period July 2005 to December 2023. The findings indicate that increases in global food prices led to a significant rise in the Consumer Price Index (CPI), indicating inflation. The study also provides empirical evidence of the asymmetric effect of changes in international food prices on the CPI. The exchange rate emerged as the variable with the most influence on inflation, with the depreciation and appreciation of the local currency. Lessons from these findings, in implementing monetary policy, authorities need to focus on inflation originating from supply shocks, which are influenced by changes in global energy and food prices and exchange rates.

Sambiloto (Andrographis paniculata) comprises andrographolide, a compound characterized by inherently low bioavailability. Consequently, it is formulated into nanoparticles to enhance its pharmacokinetic profile. Andrographolide ables to fight free radicals that cause cell death. This study was conducted to determine nephroprotective activity of poly-lactic-co-glycolic acid (PLGA)-based Andrographis paniculata ethanol extract nanoparticles in Vero cell line. Andrographis paniculata ethanol extract nanoparticles (50, 100, 250, 500, and 1000 ppm) were tested for cytotoxicity and nephroprotective activity. Nephroprotective tests consisted of acute nephroprotection, chronic nephroprotection, and recovery tests using concentrations of 100, 250 and 500 ppm. The protective effect was tested by administering nanoparticles, followed by H2O2. The recovery effect was tested by administering H2O2, followed by nanoparticles. All tests were carried out using the 3-(4, 5-dimethyl tiazol-2-il)-5-diphenyl tetrazolium bromide (MTT) assay method and data analysis was performed using one-way ANOVA. Andrographis paniculata ethanol extract nanoparticles (50-1000 ppm) did not have any toxic effect on Vero cell line. Nanoparticles provide nephroprotective activity based on concentration-dependent trend. High concentration nanoparticles (500 ppm) were able to provide better acute protective effect than vitamin E. Nanoparticles 500 ppm provided a better recovery effect (p<0,05) than vitamin E, but the chronic protection effect was lower than vitamin E. it can be concluded that Andrographis paniculata ethanol extract PLGA nanoparticles with concentration of 500 ppm provide effective nephroprotective activity against H2O2-induced toxicity in Vero cells line.