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.

     The deformation and distribution of force were investigated in different-sized rectangular shapes of polymethyl methacrylate (PMMA). The experiment involved inducing stress-strain on the surface of each sample based on a point loading of 688 N, followed by observation of the isochromatic fringe order and strain distribution using reflection photoelasti city. The samples were tested vertically between the clamps inducing the point loading. It was found that the fringe order and strain value depended on the sample size (different vertical heights and horizontal widths, with a constant thickness). The maximum strain and fringe order for the contact points on the samples decrease in the vertical direction from the contact point to the center and in a horizontal direction from the center to the edge of the sample. Based on a constant height and different widths of samples, the lowest width had the highest fringe order (4). Based on a constant width of the sample and different heights, the lowest sample height had the highest fringe order (5.5) and a microstrain value of 1,100. Therefore, the smaller the width or height of a sample, the greater the extent of deformation and distribution of force into the sample’s area.

     This study investigates the spatial dynamics of plant disease spread by expanding upon an existing spatial model. The model incorporates key factors such as host-pathogen interactions, spore dispersal, and landscape heterogeneity. Two distinct landscape types, clustered and non-clustered, were simulated to assess the influence of spatial structure on disease dynamics. Sensitivity analysis was conducted to evaluate the impact of host fraction, spore migration rate, and dispersal kernel parameters on disease spread. Results from the base case simulations demonstrated distinct disease progression patterns in clustered and non-clustered landscapes, highlighting the significant influence of host aggregation and landscape structure on disease dynamics. The sensitivity analysis revealed that host fraction and dispersal kernel parameters exerted the most significant influence on disease spread in both landscape types. These findings emphasize the crucial role of spati al factors in plant disease dynamics and highlight the importance of incorporating landscape heterogeneity and spatial variability in disease management strategies.

     Thailand is one of the most famous silk production regions, where silkworms (Bombyx mori Linn.) have been reared for sericulture for a long time. Thai silk holds the cultural importance. Several strains of silkworm have been bred and preserved by the Queen Sirikit Department of Sericulture, national administration responsible for maintaining silkworm strains in Thailand. Their efforts aim to improve the silkworm strains with desired traits and breed these traits into future generations. Therefore, the production of genetic database of silkworm reference genome, including genome annotation is crucial. This study aimed to present and annotate the polyvoltine silkworm reference genome through de novo genome sequencing of strain Nang Tui which exhibits high silk productivity and tolerance to high temperature. The estimated size of draft de novo genome assembly of strain Nang Tui was 701,413,529 bp containing 21,421 contigs. The completeness of genome assembly of Nang Tui was validated using BUSCO analysis, which revealed 90.10% single-copy BUSCOs. For gene prediction, this genome assembly harbors 337 protein-coding genes and 65 transposable elements, as predicted using the B. mori gene annotation from NCBI. Moreover, 4 rRNA and 18 tRNA-related genes were identified. The most enriched gene ontology (GO) term was plasma membrane (GO:0005886). The signaling pathway had the highest number of gene enrichments based on KEGG pathway analysis. The mononucleotide repeats were the most abundant type, with the A/T motif being the most frequent in this assembly. Moreover, genes encoding fibroin and sericin which are the main components of silk were identified. Furthermore, genes encoding serine protease inhibitors which are reported to have antimicrobial activity, were also found. Accordingly, the draft de novo genome assembly of strain Nang Tui demonstrated the high completeness and comprehensive annotation, which could serve as the novel polyvoltine silkworm reference genome and make it a valuable resource for studying the genetic diversity of various silkworm species and strains in Thailand. Furthermore, it could accelerate the understanding of molecular mechanisms for superior silk production in the future.

     This research developed hardware and software for a catalytic combustion detector (CCD) using gas chromatography (GC) technique for measuring biogas mixtures in cow and rabbit dung to identify methane and hydrogen gas. A TGS6812 detector for combustion gas, a column for gas separation included inside the oven, nitrogen as a carrier gas, valves, a flow meter, and a temperature controller are the main components of the hardware. The detector consists of two sections connected by a Wheatstone bridge. Visual Studio IDE was used to design a program for recording and analyzing data. Cow and rabbit dung were used as raw materials to produce biogas for testing the developed system for biogas analysis due to their suitability for anaerobic digestion after 15 days of fermentation. Gas concentration analysis, employing peak height in the calibration equation with repetition experiments 7 times (n = 7), revealed an average methane content in cow dung and rabbit dung was 85.03% and 78.81%, respectively. Hydrogen was hardly present in either sample (0%). Confirmed using the spiking technique.

     Beltraniaceae species are commonly associated with plant litter on various hosts. During our survey of saprobic fungi on Litchi and Longan litter in southern China, three Beltraniaceae taxa were isolated. Species identification was carried out through phylogenetic analysis and the pairwise homoplasy index (PHI) using large subunit nrDNA (LSU) and internal transcribed spacer nrDNA (ITS) sequences, along with morphological characters. Two new species, Beltrania dinghuensis and Beltraniella guangzhouensis, and one new host record (Beltraniella jiangxiensis) were identified. Descriptions and photo plates are provided for all isolated species, along with an updated phylogenetic tree and an identification key of Beltraniaceae.

     The issue of high strength and low toughness in Si₃N₄ bearings has been identified as a significant challenge. Overload conditions can result in the formation of fatigue cracks at the subsurface level, ultimately leading to bearing failure. The experimental model of Si₃N₄ friction is constructed using molecular dynamics, and the process of crack generation in Si₃N₄ bearings is subjected to detailed microscopic analysis. The Si₃N₄ deep learning potential is established through first-principle calculations and DP-GEN training, which describes the interaction mode and energy between molecules. This paper examines the friction force and temperature, defect process, and crack initiation during the friction process, and provides a detailed investigation of the crack initiation mechanism of Si₃N₄ bearings. As the friction distance increases, the total friction force rises. The impact on the atomic volume of the collar, both in front and on either side, results in a reduction in the volume of the crystal. This leads to the formation of defects in the crystal structure, which in turn causes the formation of cracks in the collar. Analyzing the crack formation process in Si₃N₄ bearings provides insights that can be used to enhance the durability of bearings.

     This research aims to study the sustainability of celadon glazes by using lampang kaolin waste and longan wood ash as substitutes for rare wood ashes, such as kha and rok fa wood, as well as for replacing silica and feldspar, which are chemicals. The celadon glazes was fired at lower temperatures of 1230°C and 1250°C in a reducing atmosphere. The analysis of the specific characteristics revealed that the glazes formula CG25-20, consisting of 30 wt.% Lampang kaolin, 20 wt.% Lampang kaolin waste, and 50 wt.% longan wood ash, with the addition of 1 wt.% sankamphaeng red clay for coloring, fired at 1250°C, had a chemical composition dominated by CaO, followed by SiO₂, Fe₂O₃, Al₂O₃, K₂O, TiO₂, SO₃, and MnO, respectively. The glaze exhibited a complete glassy morphology, with crack patterns limited to the upper surface, and the glazes adhered well to the clay body. The property tests showed that cracks decreased when 20% silica from Lampang kaolin waste was used. After firing, the glaze exhibited a green-yellow tone with L = 67.41, a = -2.13, b = +14.96, and a gloss level of 40 GU. The glazes demonstrated heat resistance, with a MOR loss percentage of 0.48, based on thermal shock testing, and had a low thermal expansion coefficient in relation to the clay body. Therefore, it is feasible to use lampang kaolin waste and longan wood ash to enhance the sustainability and heat resistance of environmentally friendly celadon glazes for ceramic ware from the sankamphaeng kiln site in Chiang Mai province.

     Gekko liboensis is a karst-dwelling endemic species to China, with identification currently based solely on morphology. This study presents the first complete mitogenome of G. liboensis, collected from Libo, Guizhou, China. The genome is circular, spanning 18,079 bp, and contains 37 typical mitochondrial genes of the family Gekkonidae and one control region. Phylogenetic reconstructions, based on nine complete mitochondrial genomes and 25 concatenated 16S rRNA and ND2 sequences using Maximum Likelihood and Bayesian Inference methods, support the placement of G. liboensis within the subgenus Japonigekko, identifying G. paucituberculatus as its closest relative. These findings support previous morphological and phylogenetic studies within Japonigekko taxonomy. The newly obtained genomic data enhance our understanding of mitogenome structure and offer valuable insights into the genetic diversity and evolutionary background of G. liboensis. This study contributes to the growing genomic resources for gekkonid reptiles and aids future phylogenetic and conservation research.