Chiang Mai Journal of Science

     Enzymatic browning in fresh-cut lettuce remains a critical challenge in the food industry, driving the search for effective natural preservatives. This study explores the innovative encapsulation of rambutan (Nephelium lappaceum L.) peel bioactive compounds with chitosan to enhance their stability and bioactivity. Among the various rambutan peel extracts (RPE) evaluated, the methanolic extract exhibited the highest DPPH scavenging activity (IC₅₀: 2.28 ± 0.15 μg/mL), correlated with its total phenolic content. The ethanolic extract also demonstrated strong antioxidant activity (IC₅₀: 3.26 ± 0.17 μg/mL) and was selected for further studies due to its balanced antioxidant performance and suitability as a food-grade solvent for potential commercial applications. Liquid chromatography-mass spectrometry (LC-MS) analysis identified Sanguiin H11 and ellagic acid as the key phenolic compounds. Notably, ellagic acid demonstrated strong molecular docking with polyphenol oxidase (PPO), showing a binding energy of -6.75 kcal/mol through specific hydrogen bonding through HIS296 interactions. The molecular docking results indicated that ellagic acid has a superior binding affinity compared to the reference inhibitor tropolone (-5.20 kcal/mol). The optimized chitosan encapsulation system (10:1 w/w RPE: chitosan ratio) produced uniform spherical microcapsules (3403 ± 8.79 nm) with excellent colloidal stability (zeta potential: 31.17 ± 0.83 mV) and high encapsulation efficiency (60.53 ± 0.48%). This formulation significantly enhanced both DPPH radical scavenging activity (6.99-fold increase) and green oak lettuce polyphenol oxidase (goPPO) inhibition (2.29-fold improvement) compared to the chitosan control group. This research demonstrated the successful conversion of agricultural waste into effective natural preservatives with PPO inhibitory and antioxidant activities, offering a promising solution for fresh-cut produce preservation.

     Based on the seasonal characteristics of infectious diseases, we present a non-autonomous compartmental model that considers mild and severe infection populations. We adopt different isolation methods for these two infected populations. The transmission period is divided into off-season J₁ and peak season J₂ . This study aims to provide the theoretical basis for controlling such infectious diseases. First, we use the Lipschitz condition to prove the model has a unique solution. Then, we construct a periodic linear system and obtain its fundamental solution matrix . The basic reproduction number is given by the equation . Furthermore, the disease-free equilibrium is globally asymptotically stable if . In addition, sensitivity analysis shows that if there are more mild infections within a period, then the infection rate ( ) and home isolation rate have a significant impact on . If the proportion of peak season is high, then we have . It indicates that reducing the infection rate can effectively control the spread of the epidemic compared with reducing . In summary, we can determine the most effective way to control the disease based on the number of mild and severe patients and the proportion of off-season and peak-season. Finally, we select two sets of parameters for numerical simulation.

     Encapsulation of plant growth-promoti ng rhizobacteria (PGPR) is a powerful strategy to support agricultural sustainability by increasing plant growth and yield, while reducing the use of chemical fertilizers. This study aimed to assess candidate formulations to encapsulate Priestia aryabhattai KNB6 using sodium alginate supplemented with alternative organic additi ves, by determining bead properties and bacterial survival. In addition, the effects of encapsulated KNB6 on rice growth, nutrient uptake, and rice development were investigated. Encapsulating P. aryabhattai KNB6 with 2% sodium alginate enriched with 1% skim milk provided the favorable properties of the smallest microbead size (0.31 mm), the highest encapsulati on efficiency (99.5%), and the greatest bacterial survival (100%). Scanning electron microscope (SEM) imaging exhibited oval bead shape with P. aryabhattai KNB6 embedded in alginate-skim milk matrix visible on bead surface. In a release test the encapsulated bacteria had multiplied in the beads and were continuously released from microbeads effecti vely carrying 10⁸ CFU/g. For plants grown in soil with limited availability of P, inoculation of KNB6 either as cells or in encapsulated form increased plant growth by its P solubilizing activity. In the pot experiments with application of chemical fertilizer, inoculation with KNB6 conferred better plant growth and development than without these bacteria. KNB6 free cells and encapsulated KNB6 increased plant dry mass by 109.7% and 74.9%, with chlorophyll contents raised by 10.3% and 5.1%, respectively. Nutrient uptake of plants treated with free KNB6 cells and immobilized ones improved, especially in their N and P adsorption increases by 82.3% and 86.1% and 47.4% and 33.4%, respectively. Moreover, all the treated plants developed obvious rice cracking. The results demonstrate that the encapsulated form of P. aryabhattai KNB6 has potential to be developed to serve as a bio-inoculant that increases soil nutrient availability and improves plant growth, thereby supporti ng sustainable agriculture.

The longitudinal decision-making control of connected vehicle platoons is critical to ensuring safety and efficiency. This study proposes a differential game-based control strategy for vehicle platoons, incorporating control variables such as vehicle state, acceleration, and engine delay. A differential game framework is formulated, establishing the objective function and state transition equations based on platooning goals and spacing policies. The longitudinal control problem is then transformed into an optimal control problem, and the Nash equilibrium strategy is derived by solving the Hamilton-Jacobi-Bellman equation. A double-predecessor-following topology is further introduced to refine the objective function. Simulation results in a longitudinal platoon environment demonstrate that, under the TPF topology, the control model reduces spacing error by 48.59%, offering improved stability, accuracy, and safety. This differential game-based strategy effectively meets platooning control objectives and enhances the stability of connected vehicle longitudinal control.

     The kinetics of water exchange around Mg²⁺ ions in aqueous solutions is a fundamental process with significant implications in biological and chemical systems. This study employs a combination of molecular dynamics (MD) simulations, time-independent component analysis (tICA), and Markov State Modeling (MSM) to investigate the underlying dynamics and free energy landscape of this rare event. Using manually selected features, including Mg²⁺-oxygen distances and solvation shell coordination numbers, tICA identifies two dominant time-independent components (TICs) governing the slowest motions, with the primary TIC dominated by the Mg²⁺-oxygen distance (dMgO). The free energy landscape reveals distinct basins for a water molecule in the first and second solvation shells, separated by a barrier of at least 27.0 kJ/mol, consistent with experimental and theoretical values. MSM resolves the longest timescales that several orders of magnitude higher than tICA, which is more consistent with the previous results. The Chapman-Kolmogorov (CK) test confirms the Markovianity of the dynamics, validating the MSM approach. This work demonstrates the potential of integrating tICA and MSM to isolate slow dynamical processes and identify key features for free energy simulations, providing a foundation for future studies to elucidate the kinetics of ligand exchange reactions and other rare events in aqueous systems.

     Carbofuran is a carbamate pesticide commonly used to control insects on various field crops. The pesticide residues on fruits and vegetables are potentially toxic to humans. Calcium chloride (CaCl₂) is a potential chemical for rinsing pesticide residues from the surface of fruits and vegetables. Eggshell waste, rich in calcium carbonate, is a possible resource for calcium for the low-cost producti on of CaCl₂. This research aimed to extract calcium from chicken eggshells with a 10% (w/v) hydrochloric acid (HCl) solution and investigate the removal efficiency of carbofuran residues from the surface of cucumber (Cucumis sativus Linn.) using the indirect spectrophotometric detection of methylamine at an absorbance of 530 nm. The maximum yield of 80.28% (w/w) eggshell extract and 81.74% (w/w) anhydrous CaCl₂ was obtained. The carbofuran concentration was 11.20 ± 1.49, 114.56 ± 24.56, and 169.68 ± 29.04 mg/L after being soaked in 1%, 2%, and 3% (w/v) of the eggshell extract solution for 10 minutes. No carbofuran residue was detected in the distilled water (control). CaCl₂ tablets were formed by compression of dried CaCl₂ extract. The increase in the compression forces from 0.5 to 1, 1.5, and 2 tons/cm² decreased the thickness of the pellets from 7.01 ± 0.07 to 6.03 ± 0.12 mm, and increased the tablet hardness from 5.27 to 11.43 kg/cm², the percentage of fracture (weight loss) from 2.18 ± 0.90 to 12.44 ± 2.45%, and the dissolution time from 4.76 to 6.72 min.