Suan Sunandha Science and Technology Journal

Reinforcing Fiber-Cement Composites for Flooring with Fibers from Low-Grade Coal Fly Ash

Mon, 14 Jul 2025 00:00:00 +0700

Low-grade coal fly ash (LGFA) is characterized as fly ash with a sulfur trioxide (SO₃) content exceeding 5%, according to the ASTM C618 standard. The fibers derived from this LGFA, combined with dolomite and basalt, served as the reinforcing phase in fiber-reinforced cement composite (FRCC) samples designed for flooring systems. These FRCC samples were manufactured using the filter pressing method and subjected to air curing for 7 and 28 days. Following the curing process, a three-point bend test was conducted to assess their modulus of rupture (MOR) and modulus of elasticity (MOE), an impact test was performed to measure their impact strength, and their bulk density was determined using Archimedes method.Low-grade coal fly ash (LGFA), as defined by ASTM C618, is fly ash with a sulfur trioxide (SO₃) content exceeding 5%. This LGFA can be used with dolomite and basalt to produce fibers for fiber-reinforced cement composite (FRCC) specifically designed for flooring systems replacing the more expensive PVA fibers. Specimens of the FRCC flooring were fabricated using the filter-pressing method and cured in air for 7 and 28 days. Following curing, the modulus of rupture (MOR) and modulus of elasticity (MOE) were determined from three-point bend tests. The results demonstrated that both MOR and MOE of the FRCC specimens increased with longer curing durations. While statistical analysis revealed no significant correlation between LGFA fiber content and MOR, a positive linear relationship was observed between LGFA fiber content and the MOE, indicating an enhanced elastic modulus with greater LGFA fiber content. Both values meet or exceed the ASTM standard required for flooring boards while making use of a waste product at a lower manufacturing cost.

Actinomycetes as Effective Biocontrol Agent Against Soft Rot Disease on Choy sum Caused by Erwinia carotovora pv. carotovora

Khanungkan Klanbut; Penkawee Kottip, Naruebet Srikaew, Naritsara Sinchoo — Mon, 14 Jul 2025 00:00:00 +0700

Soft rot disease caused by Erwinia carotovora pv. carotovora severely affects Choy sum (Brassica rapa var. parachinensis) production, particularly in tropical regions such as Thailand. Conventional control methods rely heavily on chemical pesticides, raising concerns about environmental sustainability. This study aimed to explore indigenous Actinomycetes from rice field soil in Suphan Buri Province, Thailand, for their potential as biological control agents against soft rot disease and as plant growth promoters. Sixty actinomycete isolates were screened using the agar plug diffusion method, and four isolates (SPB1012, SPB1001, SPB1035, and SPB1022) exhibited significant antagonistic effects against E. carotovora pv. carotovora. Among them, SPB1012 demonstrated the highest inhibitory activity and effectively promoted growth parameters such as shoot height and stem diameter in greenhouse experiments with Choy sum. Molecular characterization revealed 100% sequence similarity between the isolates and Streptomyces hygroscopicus subsp. hygroscopicus NBRC 13472^T. These findings suggest that indigenous Actinomycetes from rice fields can serve as promising biocontrol agents for sustainable vegetable production, reducing reliance on chemical pesticides and contributing to environmentally friendly agricultural practices.

Biotechnological Potential of Marine-Derived Fungi for Textile Dye Degradation via Laccase-Like Activity

Mon, 14 Jul 2025 00:00:00 +0700

The complex structure of synthetic dyes has made them challenging to decolorize, despite their widespread use in a variety of industries, including textiles, cosmetics, printing, paper, and pharmaceuticals. Enzymes such as oxidoreductases and peroxidases are employed in novel biotechnological procedures. An affordable and environmentally friendly solution to the issue of decolorizing commercial dyes is the use of oxidative enzymes, such as laccases derived from fungi. This study screened marine-derived fungal strains isolated from five coastal areas in Lagos, Nigeria, in order to identify laccase-like activities and assess the isolates' ability to decolorize industrial dyes in solid and liquid media by monitoring the radial growth, percentage decolorization, biosorption, and laccase activity after seven days of incubation with the dyes. After several steps of culturing on potato dextrose agar (PDA) plates, forty pure fungal cultures were isolated from a total of 100 samples (wood, nets, plants, clothing materials, soil, and water) collected from five different marine biotopes in Lagos: Oniru Beach, Makoko Lagoon, Elegushi Beach, Adekunle Lagoon, and Unilag waterfront. Through preliminary oxidative ability screening with 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), eleven isolates were discovered. Six strains of Meyerozyma guilliermondii, two strains of Rhodotorula mucilaginosa, one strain of Candida tropicalis, and two strains of Penicillium oxalicum were identified as belonging to the following species by means of molecular-based taxonomic approaches. Meyerozyma guilliermondi A4B and Penicillium oxalicum M6A effectively decolorized four synthetic dyes from various dye families and demonstrated the highest level of oxidative capacity and grew best at 2 mM CuSO₄ as an inducer and 2% and 1% NaCl to mimic a marine environment, and both produced the highest laccase-like active cell-free supernatants activity.