Chiang Mai Journal of Science

     In this study, a compact and low-cost ammonium detector integrated spectrophotometric and fluorescence detection was designed based on the reaction of ammonium and o-phthalaldehyde in the presence of sodium sulfite solution to form substances with both photometric properties and fluorescence. This two-in-one detector detects ammonium in spectrophotometric mode at high concentrations and in fluorescence mode at low concentrations. The detector with a total size of 5×5×5 cm² and integrates the detector skeleton box, light source, attenuator, filter, photoelectric sensor, data acquisition card, constant current source circuit, and LabVIEW upper computer acquisition program. Also, the detector was applied to the determination of water samples with a wide range of ammonium concentrations, showing good performance. The detector has the advantages of low cost, miniaturization, easy operation, and wide detection concentration range. This two-in-one detector has good potential for ammonium detection in the field, especially where ammonium concentration varies widely.

The surface browning of fresh-cut products not only diminishes their nutritional content but also lowers their market value. Fresh-cut banana blossom (FBB), an increasingly popular vegan food, is prone to browning on the cut surface, which poses a significant challenge for this fresh-cut produce. Chemicals and natural extracts are commonly used to address this issue in fresh-cut produce, offering alternatives to synthetic chemicals. Tamarind (Tamarindus indica L.) pulp extract (TPE), derived from the tamarind fruit, contains compounds such as polyphenols with antioxidant properties, making it an intriguing choice as an anti-browning agent. Therefore, this study investigated the effects of TPE on surface browning and reactive oxygen species (ROS) metabolism in FBB during storage at 30 ± 1 °C. FBB was immersed in 0 % (the control) and 2.5 % TPE for 5 min, then rinsed with distilled water, air-dried, and stored at 30 ± 1 °C for 60 h. The control group showed increasing surface browning and declining overall quality during storage. TPE immersion significantly enhanced antioxidant defense systems during storage compared to the control. The heightened activity of antioxidant enzymes and increased non-enzymatic antioxidant levels corresponded with decreased ROS levels, oxidative membrane damage, and surface browning. These findings suggest that TPE has the potential to effectively reduce browning in FBB and may serve as an effective anti-browning agent for other fresh-cut products.

In this study, waste magnesite (WM) particles with different weight fractions (2.5%, 5%, and 7.5%) were used as particulate material in 6061 aluminium alloy to produce composites with improved properties. The composite material was manufactured using a stir-casting method. A surface morphology investigation confirms the uniform distribution and good interfacial bonding of the WM particles within the alloy base. The addition of 5% WM particles was found to improve the values of tensile strength of 146.68 MPa, hardness of 131.6 HV and coefficient of friction of 0.565. Incorporating 7.5% WM was found to give a low wear of 161 μm and a corrosion current of 8.5 x 10^-6 A. The results obtained confirm that such a proportion of WM particles in Al 6061 alloy provides excellent anticorrosion protection, wear properties, and good mechanical properties. Adding 5% WM to Al 6061 improves overall performance characteristics among other ratios.

     Fungal pathogenicity is one of the most vigorously tackled ecological and medicinal issues facing many scientists. Comparative genomics is an extremely important methodology and tool used to understand fungal pathogenicity, and it allows the development of early diagnostic tools for fungal-inflicted diseases across different host organisms. However, comparative genomics depends heavily on readily available fungal pathogenic gene databases to enable downstream genomics study and the development of new diagnosis and detection methods. Here, we have developed the Common Fungal Pathogenic Genes Database through comparative genomic analysis using 86 publicly available fungal genomic data against fungal pathogenicity-related databases, such as Pathogenic-Host Interaction Database (PHI-base), Carbohydrate-Active enZymes Database (CAZy), and Database of Fungal Virulence Factory (DFVF).

     This study investigates the acoustic properties of nipa palm peduncle fiber (NPPF) composites, a promising natural fiber with a tensile strength of 277 MPa, a yield strength of 49.0 MPa, and a Young’s modulus of 12.0 GPa. We focus on understanding how NPPF’s physical characteristics influence its sound absorption and insulation capabilities. Through experimental analysis, we found that the sample density directly affects the sound absorption coefficient (SAC) and transmission loss (TL), with denser samples exhibiting better noise reduction. Using the Johnson-Champoux-Allard-Lafarge (JCAL) model, we correlated these acoustic properties with the material’s non-acoustic parameters including flow resistivity (σ), open porosity (), tortuosity (α_∞), viscous (Λ) and thermal (Λ' ) characteristic lengths along with static thermal permeability (k₀'). The results validate the JCAL model’s predictions, offering insights into designing effective, eco-friendly acoustic materials. This study not only highlights NPPF composites’ notable acoustic performance but also underlines their potential for contributing to sustainable development.

     Hydroponics is a common soilless type of culture. It is clean and gives high-yield crop production. Lettuce is the most widely grown leafy vegetable in hydroponics. The Pythium species causes root rot, a serious disease in lettuce. In this study, we investigated an effective elicitor to promote resistance in lettuce after pathogen infection. To evaluate the plant defense gene response profile, the expression stability of five candidate genes was studied using RT-qPCR. The LsPR1 and LsLTC2 gene expression were higher in lettuce leaves treated with non-pathogenic Pythium PyASR23 than in roots compared to untreated plants. To assess the disease, the rate of relative gene expression of LsLTC2, LsPR-1b like, LsERF, LsAOS, and LsDEF was associated with Pythium root rot pathogenesis. As a result, it was revealed that alterations in these gene expressions were a defense response to Pythium infection, which increased after pre-treatment with various elicitors for 24 hours. When the chemically stimulated lettuce was infected with pathogenic PySR31, the expression of these genes increased dramatically. These results suggested that non-pathogenic PyASR23 might be employed as an elicitor in lettuce roots and contribute to disease control by activating plant defense gene expression against the Pythium pathogen.

     Sri Lanka is an island nation with diverse ecosystems, including forests, wetlands, grasslands, and vast coasts. The country showcases a rich aquatic ecosystem that includes both coastal and inland waters. Freshwater habitats such as rivers, streams, marshes, and man-made reservoirs are the host for diverse fungal communities. However, documentation and identification of freshwater fungi in Sri Lanka have not yet been done as they face significant challenges, including unexplored taxa, misidentification, and hitherto reliance on morphological data, as well as limited funding, awareness, and expertise. This study aims to assess the limitations, potentials, and conservation efforts related to the identification of fungi in freshwater habitats in Sri Lanka. The assessment has revealed several potential opportunities for future research, including the exploration of novel fungal strains that are found in freshwater habitats, identification and classification of existing fungi, setting up and utilization of the freshwater fungal repository, access to reference databases, and identification of industrial applications.

    This research aimed to study the geopolymer paving blocks made from fly ash and bagasse ash under different curing conditions. The fly ash was replaced by bagasse ash at 10, 20 and 30% by weight of the binder. Sodium hydroxide and sodium silicate solutions were used as activated solutions. Three curing methods were studied: curing with plastic wrap (PT), curing at 35 °C for 1 hour (OV), and curing with sunlight (SU). Compressive strength and water absorption were investigated. The surface characteristics of the geopolymer paving block were studied using microstructure techniques. Sun curing provided the highest compressive strength. The water absorption values increased with an increase in the replacement percentage of bagasse ash. The surface of the geopolymer paving blocks showed remnants of the starting materials from the reaction. The geopolymer paste from the geopolymerization reaction was also found. This indicated the beneficial use of waste materials to produce environmentally friendly building materials.

     The quality of vermicelli was deemed dependent on gel characteristics. Alum was traditionally employed to modify gel characteristics for quality enhancement in potato vermicelli products. In this study, whey protein was added to boost the gel characteristics of potato starch, with the goal of improving vermicelli quality. It was observed that the peak viscosity, G', G", swelling characteristics, and dehydration of the potato starch gel were significantly reduced with the addition of whey protein. At the same time, a more continuous and dense honeycomb porous structure was gradually formed in the gel network with whey protein, facilitating a more compact potato starch gel network. The tight accumulation of the potato starch gel network was facilitated by this change. Significant increases were observed in the hardness, cooking loss, and water holding capacity of the vermicelli with the addition of whey protein. The swelling characteristics of the vermicelli gradually decreased, leading to a milky yellow color. When the whey protein addition was 4%, the textural and sensory characteristics of the vermicelli were found to be comparable to those of alum-treated vermicelli in overall sensory scores. It was demonstrated in this study that the gel characteristics of potato starch could be enhanced by whey protein, thereby improving the quality of vermicelli.