PSRU Journal of Science and Technology

INFLUENCE OF SURFACE MODIFICATION AND FIBER LOADING ON THE PROPERTIES OF RICE STRAW-REINFORCED EPOXY COMPOSITES

Sawitree Suckley — 2025-08-29

Fiber-reinforced composites have found extensive applications in construction, automotive, aerospace, and many fields. As a result of global sustainable development and environmental concern, however, natural fibers have become increasingly attractive over synthetic fibers due to their light weight, low cost, abundance, and biodegradability. This study has been carried out to evaluate the potential use of rice straw fiber as a reinforcement material for epoxy composite. Rice straw fibers were treated with NaOH aqueous solution and silane coupling agent, respectively, before they were applied into epoxy composites. The effect of surface modification and fiber contents on mechanical properties was investigated by flexural and impact tests. Compared with untreated rice straw fiber reinforced epoxy composite, fiber treated with 3% NaOH followed by 3% silane coupling agent showed the highest flexural strength and the maximum flexural strength was obtained at 15% fiber content. The untreated rice straw fiber reinforced epoxy composite, however, showed the highest impact strength as compared to all treated fibers and the maximum impact strength for untreated rice straw fiber filled epoxy composite was also obtained at 15% fiber content. The surface modified rice straw fiber composites exhibited lower water absorption values than those of untreated fiber-based composites.

EFFICIENCY OF SUPERCAPACITOR WITH ACTIVATED CARBON FROM TAMARIND SEED

Sanit Suwanwong — 2025-08-29

Phetchabun Province has sweet tamarind which is an important economic fruit. Tamarind is consumed and processed into tamarind pulp products, the remaining residue is tamarind seeds and pod shells, can be synthesized into activated carbon that has a variety of uses, including in the energy field being used to make the electrodes of supercapacitors. In this research, the efficiency of activated carbon from tamarind seeds was increased by mixing it with carbon black in the following weight ratios: 1.00 : 0.25, 1.00 : 0.67, 1.00 : 1.00, 1.00 : 1.50, and 1.00 : 4.00. The resulting mixture was then coated onto aluminum foil to be used as the electrode of a coin cell supercapacitor. The pore size and surface area were analyzed using a Brunauer-Emmett-Teller; BET analysis found that the activated carbon from tamarind seeds had a smaller pore size than the tamarind fruit shell and tamarind seeds has a much higher surface area than tamarind fruit shell. Therefore, activated carbon from tamarind seeds was chosen for use. In Scanning Electron Microscope (SEM) images, carbon black can be seen adhering to activated carbon from tamarind seeds. In examining the functional groups using the Fourier-transform infrared spectroscopy (FT-IR) technique, it was found that at the wavenumber position of 3,400 cm^-1 there was an O-H stretch bond, with the ratio 1.00 : 0.67 has the highest absorption. In the range of 1,200-500 cm^-1 is the range with a large number of carbon bonds found that activated carbon from tamarind seeds mixed with carbon black had high adsorption. Analysis of the efficiency of supercapacitors made from tamarind seeds and mixed with carbon black found that they had a higher specific energy density value and a higher specific capacitance value compared to tamarind seeds and carbon black alone. Therefore, activated carbon from tamarind seeds is suitable for application as a supercapacitor.

ENHANCING GERMINATION AND SEEDLING GROWTH OF PEANUT TAINAN 9 VARIETY THROUGH SEED COATING WITH ENTEROBACTER KOBEI

Saralee Prommayakul — 2025-08-29

Peanuts can be grown year-round, yet the supply remains insufficient to meet consumer demand. This shortfall is primarily due to high cultivation costs from fertilizer use and poor-quality seeds, which result in uneven germination, weak seedlings, and susceptibility to pests and diseases. To address these issues, seed coating technology is essential for enhancing seed quality before planting. This study aimed to determine the optimal concentration of Enterobacter kobei for seed coating and to evaluate its effects on various seed quality parameters. The results indicated that coating seeds with E. kobei at 6.60x10⁸ CFU/mL significantly improved germination rates and speed of germination compared to non-coated seeds under both sand and greenhouse conditions. Additionally, seeds coated with E. kobei at concentrations of 6.60x10⁸ CFU/mL, 6.60x10⁹ CFU/mL, and 6.60x10¹⁰ CFU/mL exhibited significantly greater shoot length, root length, seedling length, shoot fresh weight, root fresh weight, shoot dry weight, and root dry weight in both testing conditions. In conclusion, coating peanut seeds with E. kobei at 6.60x10⁸ CFU/mL is recommended for enhancing the germination, vigor, and growth of Tainan 9 peanut seedlings.

ASSESSMENT OF HEAVY METAL CONTAMINATIONS IN RICE: A CASE STUDY OF KOH RAI SUBDISTRICT, BAN PHO DISTRICT, CHACHOENGSAO PROVINCE

Kitiya Totong — 2025-08-29

This study aims to assess the levels of heavy metals, including manganese (Mn), copper (Cu), zinc (Zn), cadmium (Cd), and total arsenic (Total As), contaminating rice grain samples after harvest from five rice fields in Koh Rai Subdistrict, Ban Pho District, Chachoengsao Province. The analysis of heavy metals in jasmine rice samples was conducted using Inductively Coupled Plasma Mass Spectrometry; ICP-MS while also observing the agricultural chemical practices of the farmers in all five fields. The results indicated that the rice samples had the highest manganese contamination (14.799-31.479 mg/kg) followed by zinc, copper, total arsenic, and cadmium, respectively, with concentrations ranging from 14.549-18.368, 2.393-3.859, 0.094-0.105, and 0.013-0.032 mg/kg, respectively. These contamination levels are within the standards set by the Ministry of Public Health of Thailand. Additionally, the levels of heavy metal contamination in the rice samples may be related to the agricultural chemical practices of the farmers. Therefore, farmers should reduce the use of chemical agricultural substances by using them only when necessary and experiment with the use of effective organic-biological substances as substitutes. This will help reduce the problem of chemical residue accumulation in the produce, lower production costs, and benefit the health and safety of both farmers and consumers in the food chain.

EFFICACY OF EMULSIFIED KAFFIR LIME PEEL ESSENTIAL OIL AGAINST SALMONELLA TYPHIMURIUM ON BASIL LEAVES

Umaporn Thathaisong — 2025-08-29

This study aimed to test the efficacy of emulsified kaffir lime peel essential oil against Salmonella Typhimurium (S. Typhimurium) on basil leaves. The minimum inhibitory concentration; MIC and minimum bactericidal concentration; MBC were determined by Macrobroth dilution. The MIC and MBC values were both 0.50%. The time-kill assay indicated that the emulsified kaffir lime peel essential oil concentration of 0.50% effectively killed >99.90% of the initial bacterial population within 5 minutes. Moreover, the antimicrobial activity of the emulsion against S. Typhimurium on basil leaves was tested. Compared to the control, the emulsion at concentrations of 0.50% (1xMIC) and 1% (2xMIC) showed significant reduction (P<0.05) in S.Typhimurium on the basil leaves. Wash treatment with 1%(2xMIC) exhibited greater significant effects on the pathogenic bacteria than 0.50% (1xMIC) (P<0.05). In addition, wash treatment with both concentrations of emulsified kaffir lime peel essential oil did not affect the color of basil leaves (P>0.05). The results from this study indicated that emulsified kaffir lime peel has efficacy in the decontamination of S. Typhimurium on basil leaves which can be applied to be as an alternative as a sanitizer for fresh vegetables.

EFFECT OF DRYING METHODS OF CANNABIS AND PROPORTIONS OF HERBAL TEAS CONTAINING CANNABIS ON BIOACTIVE COMPOUNDS, AND ANTIOXIDANT ACTIVITY

Sukanya Maikuakeaw — 2025-08-29

This research aims to study the effects of drying heat on the concentrations of significant compounds and antioxidant activity in cannabis, as well as the impact of herbal components on these properties in herbal tea containing cannabis. Cannabis sativa L. “Hang Kra Rog” strain leaves were dried using a hot air oven at 45^°C and 60^°C, and freeze-dried. Both the dried cannabis leaves and herbal tea products were finely ground and analyzed for THC and CBD content, while antioxidant activity was measured using the DPPH method. The dried cannabis leaves, dried using a hot air oven at 45^°C, were also mixed with other herbs to create three herbal tea formulas. The results revealed that drying cannabis leaves at 45°C in a hot air oven produced the highest THC content (6,003.22±3.10 mg/kg), while no CBD was detected in cannabis leaves dried by any method. Significant differences (P≤0.05) in antioxidant levels were observed across the different drying methods. Formula 3, consisting of 10% dried cannabis leaves, 60% miracle grass, and 30% chamomile, exhibited the highest antioxidant activity, with THC and CBD levels compliant with Ministry of Public Health standards. This study provides critical insights into determining the optimal amount of cannabis leaves for herbal tea formulations. The findings ensure that THC and CBD levels remain within the permissible limits per consumption unit, offering valuable guidance for future product development in the industry.

TOTAL PHENOLIC AND FLAVONOID CONTENTS, ANTIOXIDANT AND ANTIBACTERIAL ACTIVITIES OF ORGANIC ROSE ETHANOL EXTRACTS

Wimonrat Phottraithip — 2025-08-29

The objectives of this research were to study total phenolic and flavonoid contents, antioxidant and antibacterial activities of ethanol extracts from 3 varieties of roses, Mon Dang Prasert (Rosa damascena cv. Dang Prasert), Mon Klai Kangwon (Rosa damascena cv. Klai Kangwon) and Bishop’s castle (Rosa hybrid cv. Bishop’s castle) which are grown with organic agriculture by farmers in Chiang Dao District, Chiang Mai Province. The total phenol content was determined by Folin-Ciocalteu colorimetry, total flavonoid content by Aluminum chloride colorimetric assay, antioxidant activity by DPPH method and antibacterial activity by Agar well diffusion method. It was found that the extracts of Mon Dang Prasert, Mon Klai Kangwon and Bishop’s castle showed total phenolic contents of 606.60, 92.31, and 101.93 mg GAE/g extract, respectively. Total flavonoid contents of the Mon Dang Prasert, Mon Klai Kangwon and Bishop’s castle extracts were 178.76, 42.99 and 38.62 mg QE/g extract, respectively. The antioxidant activity showed IC₅₀ values of 7.40, 25, and 30 µg/mL, respectively, using vitamin C and trolox as standard compounds. The Mon Dang Prasert, Mon Klai Kangwon and Bishop’s castle extracts were found to inhibit the growth of two gram-positive bacteria, Staphylococcus aureus and Bacillus cereus, and inhibit the growth of one type of Gram-negative bacteria, Proteus mirabilis. All extracts were inactive to inhibit the growth of Escherichia coli, a Gram-negative bacteria. The results of this study can be used as information for developing health supplement products in the future.

AN OVERVIEW OF THE PATHOGENESIS, TRANSMISSION, AND PREVENTION STRATEGIES OF RAT-BITE FEVER IN HUMANS

Nantawat Thammajai — 2025-08-29

Rat bite fever (RBF) is a zoonotic disease caused by the bacteria Spirillum minus, Streptobacillus moniliformis, and Streptobacillus notomytis. In 1926, an S. moniliformis outbreak in Haverhill, Massachusetts, linked to contaminated milk, caused “Haverhill Disease.” S. moniliformis is prevalent in the Americas, while S. minus is more common in Asia. In 2018, Okinawa, Japan, documented the first human case of RBF caused by S. notomytis (Fukushima et al., 2018). Key animal carriers include rodents such as black rats (Rattus rattus) and brown rats (Rattus norvegicus), which asymptomatically harbor these bacteria as part of their natural flora. The disease is transmitted to humans through wounds from bites or scratches. Infected individuals typically present with high fever, rash, and painful swelling in the joints. Without treatment, the mortality rate can reach up to 10%, with complications such as myocarditis, pericarditis, and meningitis being potential causes of death. High-risk groups include individuals whose occupations involve frequent contact with rodents or those working in environments prone to rodent infestations, such as food processing facilities that often attract rodents. Treatment involves antibiotics, which significantly reduce the mortality rate. Diagnosing RBF is challenging due to the need for specific environmental conditions to isolate and culture the bacteria. This restriction is a reflection of the present knowledge gaps on the disease's pathogenic mechanisms. Prevention and control strategies focus on maintaining strict hygiene practices and avoiding contact with rodents to minimize the risk of infection.

บทบรรณาธิการ

2025-08-29

บทบรรณาธิการ

สารบัญ

2025-08-29

สารบัญ