Chiang Mai Journal of Science

     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.

     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.