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.

     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.

     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.