Chiang Mai Journal of Science

     In the present work, the characteristic of β-tricalcium phosphate (β-TCP) powder was investigated for its film coating on a Ti6Al4V metallic biomaterial. The β-TCP powder was synthesized by a solid-state reaction technique at different temperatures. The β-TCP formed at temperatures 900-1000 ^oC, while α-tricalcium phosphate (α-TCP) was occurred at higher temperatures (≥1000 ^oC). Crystallite size increased with increasing temperature, but it decreased at temperatures higher than 1000 ^oC due to the formation of α-TCP. Furthermore, the amount of α-TCP phase increased with temperature. However, maximum crystallite size and density values were found for the 1000 ^oC powder. The 1000 ^oC powder was coated on a titanium alloy (Ti6Al4V) by a dip coating technique. The coated surface presented a uniform grain with an average grain size of 3.21 μm. Bioactivity testing of the coated samples indicated that they had good bioactivity. The results indicate the possibility of developing the samples for biomedical applications.

     In the present work, ZnSe nanocrystals doped (NCs) with selenium (ZnSe:Se) were synthesized and characterized. The impact of the concentration of ZnSe:Se NCs nanocrystals on the properties of the Poly(3-hexylthiophene-2,5-diyl) (P3HT) matrix was studied with a collection of experimental and theoretical investigations of this organic-inorganic hybrid structure. The optical absorption spectra were found to be strongly dependent on the level of ZnSe:Se NCs. Theoretical analysis provided insight into the experimental data for the explanation of energy and charge transfer. The Benesi-Hildebrand diagram was use to prove the complex formation in our layers.

     Lotus (Nelumbo nucifera Gaertn.) is a species of aquatic plants in the Nelumbonaceae family. Currently, cultivation of ornamental flowers and breeding is widespread resulting in numerous hybrids and significant genetic diversity. Consequently, classification based on morphology becomes challenging and confusing. This research purposed to evaluate genetic diversity among nine samples in Phitsanulok province using sixteen qualitative and nine quantitative characters, along with three molecular markers: sequence-related amplified polymorphism (SRAP), random amplified polymorphic DNA (RAPD) and high annealing temperature random amplified polymorphic DNA (HAT-RAPD). The similarity index for the combined molecular markers ranged 0.736 to 0.990, while for morphological characteristics, it ranged from 0.440 to 0.920. Results from the molecular markers indicated that 5 SRAP, 7 RAPD and 8 HAT-RAPD primers produced an average of 38.2%, 40.2% and 28.8% polymorphic fragments per primer, respectively. The UPGMA cluster analysis based on molecular data and morphological traits grouped the Indochina Garden cultivars with those from Phitsanulok cultivars. Using the three molecular marker, seven cultivars in Phitsanulok province clustered together. In contrast, morphological characteristics separated into three groups. This suggested that two cultivars from the plant market were distinctly different from lotus cultivars in Phitsanulok province.

     The consumption of kombucha in Southeast Asia has risen significantly due to increasing awareness of wellness, leading to a high demand for novel beverages in the kombucha market. In this study, we focused on using dragon blood tea (Peristrophe bivalvis L. Merr), a local plant in Southeast Asia, as an alternative substrate for producing kombucha. The fermentation process was performed at 30°C for 15 days and compared with traditional kombucha made from green tea and black tea (Camellia sinensis L.). The microbiological properties of the three types of kombucha revealed similar growth patterns for both acetic acid bacteria and yeast. In terms of total phenolic content and antioxidant activity, green tea kombucha demonstrated the highest values, followed by dragon blood tea kombucha and black tea kombucha, respectively. Notably, dragon blood tea kombucha displayed a significant increase in total phenolic content throughout the fermentation period, whereas green tea and black tea kombucha exhibited a decrease after day 6 of fermentation. Antioxidant activity remained consistent across all types of kombucha during fermentation. Sensory evaluation revealed that dragon blood tea kombucha received the highest scores for appearance and color, although it scored lower in the aroma. These findings suggest the potential of dragon blood tea kombucha as a novel substrate for kombucha production, offering directions for future research, particularly focusing on enhancing aroma through the infusion of flowers or herbs.

       Limestone and calcined clay, due to their abundance and sustainability are seen as feasible materials to be used to replace Portland cement in the future. In this work, Portland cement was replaced with calcined clay and limestone at 50 % by weight. In addition to compressive strength, the microstructure and phase characterizations were investigated at 7 and 28 days to determine hydration and pozzolanic reaction of the mixes using thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. When using 20% calcined clay, the 50PC30LS20CC mix showed an increase in the compressive strength by 225% compared to the 50PC50LS mix. Although the compressive strength was still lower than 100 PC control mix, using calcined clay and limestone together lead to a significant reduction in the water absorption compared to 50% LS mix due to the phases formed and the filling effects, and comparable result to 100PC mix was found when calcined clay was used at 20%. In addition to calcium carbonate detected in mixes with limestone, monocarboaluminate phase was also found at 7 days and became clearer at 28 days, especially when there was a combination of calcined clay and limestone in the mix due to the presence of alumina from calcined clay. Moreover, pozzolanic reaction from the use of calcium clay resulted in the increase of C-S-H and C2ASH8 which increased with calcined clay content and corresponds with a reduction in calcium hydroxide and an increase in compressive strength.

     In this study, mung bean protein hydrolysates were prepared to evaluate their antioxidant properties under simulated conditions for food processing and in vitro digestion. Mung bean protein isolate, with a protein content of 93.6%, was hydrolyzed by Alcalase at 55 °C, pH 8, for 5-7 hours, using an enzyme-to-substrate ratio of 7%. The degree of hydrolysis (DH) was monitored during enzymatic treatment, reaching selected DH values of 50% and 55% after 360 and 420 minutes, respectively. Hydrolysates collected at 360 (H360) and 420 minutes (H420) demonstrated distinct antioxidant profiles, with H360 exhibiting optimal metal chelating activity (MCA) and ABTS radical scavenging activity. The stability of antioxidant protein hydrolysates derived from mung bean protein was evaluated under different incubation pH levels (4 and 6), at different temperatures (-18°C, 4°C, and 25°C for 24 hours; 63°C for 30 minutes; and 100°C for 5 minutes) and under in vitro digestion. Antioxidant properties were influenced by incubation pH, with higher ABTS scavenging activity observed at pH 6 compared to pH 4. However, MCA did not significantly differ between the two pH levels. Additionally, hydrolysates demonstrated thermal stability, retaining significant antioxidant activity after subjected to various temperature treatment. The hydrolysates also maintained or improved antioxidant capacity post simulated gastrointestinal digestion, highlighting their potential for functional food applications.

     The conversion of waste plastics into oil through pyrolysis presents a promising alternative energy solution, addressing the significant environmental challenge posed by the accumulation of plastic waste. Despite numerous studies in this field, few have specifically focused on the design of a pyrolysis reactor incorporating six condensers connected in series. This research aimed to investigate the influence of waste plastic type through the pyrolysis process on product yield from three types of plastic waste: polypropylene (PP), high-density polyethylene (HDPE), and multilayer plastic (ML). Pyrolysis was performed in a 50 L household reactor for a reaction time of 90 min with the heating rate of 10-15 °C/min. The results showed that the pyrolysis process produced three types of products: liquid, solid, and non-condensable gases, with liquid being the main product. The experimental results indicated that the plastic pyrolysis reactor produced the highest proportion of liquid product, followed by non-condensable gases, with only a small amount of solid residue. The liquid product yield was highest in HDPE at 82.1%, followed by PP at 74.4% and ML at 47.1%. The non-condensable gases yields were 17.8%, 25.0%, and 42.9%, respectively. The DGC technique verified the fuel properties, confirming the presence of kerosene, naphtha, diesel, and fuel oil in the chemical composition. This experiment showed that pyrolysis of plastic waste in a reactor with a fractional condensation system could generate liquid fuel oil. It offers a potential framework for the production of liquid fuel that can be used as a substitute for fossil fuels.

     Aquatic insects ar e among the most frequently used macroinvertebrates in freshwater monitoring and assessment worldwide. However, little attention has been paid to the inclusion of aquatic insects in the biological assessment of water quality and health, especially in Vietnam. In the current study, we altitudinally investigated the diversity of aquatic insects as well as their relationships with physico-chemical parameters in Thac Bac stream, Tam Dao national park, in which high-altitude sites highly experience human disturbance while low-altitude sites are conservative areas. A total of 122 species belonging to 111 genera, 56 families and 9 orders of aquatic insects were identified in the current study. Further, we found altitudinal changes, both in the biodiversity of aquatic insects and water quality parameters. The biodiversity of aquatic insects was higher in the low-altitude sites ranging from H’=3.31 in site St5 to H’=4.09 in site St6 compared to that of high-altitude stream sites ranging from H’=1.43 in site St1 to H’=2.29 in site St3. Moreover, a strong correlation between the aquatic insect biodiversity and several water quality parameters was found, in which dissolved oxygen and air temperature were positively correlated with the biodiversity index while altitude and electrical conductivity were negatively correlated with the biodiversity index. The results of this study provide a useful basis for appropriate water management using aquatic insects as bioindicators to assess human impacts on stream systems in Vietnam.

     Microalgae is one of the promising renewable fuel sources as it can optimize its biomass and lipid content. Lipid content is commonly associated with its potential as a biofuel. Nitrogen stress is an attempt to increase the metabolite content in microalgae. In this study the microalgae Euglena sp. was grown in a medium with different nitrogen concentrations to determine the number of cells, biomass, lipids, and FAME (Fatty Acid Methyl Esters) content cultivation of Euglena sp. had been carried out for 14 days with the gradually decreased concentration of nitrogen (1000 mg/L, 750 mg/L, 500 mg/L, 250 mg/L, and 0 mg/L) (NH₄)₂SO₄. The density of cells of Euglena sp. was counted under a light microscope and identification of lipids was done by measuring the lipid total using Bligh and Dryer and Fatty Acid Methyl Ester (FAME) was measured by Gas Chromatography-Mass Spectrophotometry (GC-MS) method. The results show that deficiency of nitrogen gave the lowest impact on cell growth, biomass, pigments, and carbohydrate of Euglena sp. While the lipid content increased with the highest yield obtained at the nitrogen concentration of 0% mg/L. The composition of FAME of Euglena sp. was dominated by Saturated Fatty Acid (SFA) methyl ester by 54.72%. The highest carbon chains are C16:0 and C18:0 at a concentration of nitrogen 0 mg/L. It is concluded that nitrogen starvation could increase the lipid content and FAME as biodiesel which had the potential to be converted into biojet fuel.

     Development of a portable electronic nose based on eight metal oxide gas sensors and gas chromatography (GC) analysis for classification of a difference in coffee flower odors are reported. Volatile organic compounds (VOCs) of arabica coffee (Coffea arabica Linnaeus) flowers before and after pollination were investigated. Principal component analysis (PCA) was performed for pattern recognition. The results showed that all metal oxide gas sensors exhibited sensitivity to odors of the coffee flower samples. PCA result showed good classification of coffee flower odors correctly corresponding to the samples before and after pollination. Based on GC analysis, it was found that pyrazine may be one of impact volatile organic compounds in arabica coffee flowers before pollination and amount of 2-methyl-1-butanol largely decreased after pollination. The pyrazine and 2-methyl-1-butanol may be used as a key compound for qualitative measurement using the electronics nose system with several advantages including rapid and accurate measurement, low cost and easy to use. We hope that this work will be useful for guidance on further studies of production of tea-like beverages using arabica coffee flowers.

     Sediment accumulation and alternately submerged caused by water conservancy engineering pose challenges to ecological restoration in riparian zones. In this study, a hybrid model coupling convolutional neural network (CNN), long short-term memory network (LSTM), and batch normalization (BN) techniques was employed to predict the concentrations of physiological indicators (soluble sugars (SS), soluble proteins (SP), malondialdehyde (MDA), and chlorophyll-a (Chla) content) in five herbaceous plants under varying water-sediment conditions. The findings indicated that the CNN-LSTM model outperformed the LSTM model in forecasting the overall trend and fluctuations of the data, particularly with reduced bias in predicting extreme values. Additionally, the CNN-LSTM-BN model improved predictive capabilities for the four physiological indicators. The mean absolute error (MAE) for the true and predicted values in the verification set were 0.040, 0.039, 0.017, and 0.020, respectively. The integration of the BN layer facilitated gradient propagation of the loss function across each parameter of the model, thereby accelerating learning efficiency and enhancing training process stability. Furthermore, the CNN-LSTM-BN model successfully predicted the concentrations of SS, SP, MDA, and Chla in Paspalum wettsteinii under a 3 cm water-sediment condition, yielding MAE values of 0.308, 0.249, 0.365, and 0.169, respectively. These findings highlight the strong predictive capabilities of the CNN-LSTM-BN model. Overall, this study offers valuable insights for plant selection and maintenance strategies in riparian ecological restoration efforts within the context of water conservancy engineering.

     Ecosystems and the environment are adversely affected by wastewater containing oil and grease, arising from domestic wastes. In this research, lipase-producing bacteria from a wastewater treatment pond were isolated and the ability to remove oils and grease from synthetic wastewater containing 3% cooking oil was examined. The efficiency of using scrub pad immobilized selected lipase-producing bacteria to remove oil and grease from restaurant wastewater was then investigated. Thirty-one bacterial isolates were obtained from the wastewater, and those that produced lipase were selected using Tween 80 agar. Out of all the isolates, the isolate KS915 and KS303 were chosen due to their noticeably high lipase production efficiency of 1.84±0.07 and 1.48±0.24, respectively. The immobilized KS915 and KS303 had the ability to remove 99.85% and 99.76% of the oil and grease from synthetic wastewater supplemented with 3% cooking oil, respectively. The immobilized KS303 was chosen to remove oil and grease from restaurant wastewater because of its shortened removal time in synthetic wastewater. The immobilized KS303 had an oils and grease removal efficiency of 98.37% after two days, compared to 57.78% for the control after more than ten days. The chemical oxygen demand and biochemical oxygen demand of the treated restaurant wastewater decreased by 48% and 92.1%, respectively. The isolated KS303 was identified as Aeromonas jandaei based on 16S rDNA sequence analysis. Based on these findings, A. jandaei KS303 can be a great source of lipase production and remove oil and grease from domestic wastewater.

     This study explored the utilization of waste palm oil fuel ash (PA) as a supplementary cementitious material to enhance the properties of blended Portland cement mortar. By examining the impact of PA with varying degrees of fineness, the research demonstrated how different levels of PA fineness influenced the physical and durability properties of mortar. Specifically, Portland cement type I (OPC) was substituted with PA at three distinct fineness levels, each constituting 20% of the binder’s weight. The experiments maintained a consistent water-to-binder (W/B) ratio of 0.55 and utilized a superplasticizer to preserve the standard mortar flow of 110 ± 5 %. Findings indicated that finely ground PA significantly decreased mortar porosity while enhancing compressive strength, water absorption, and chloride penetration resistance. SEM-XRD pattern analysis further revealed a more homogeneous microstructure in mortars containing finely ground PA, characterized by an increased presence of calcium silicate hydrate (C-S-H). The results suggest that ground PA not only mitigated environmental issues related to the disposal of palm oil fuel ash but also promoted its sustainable use in construction materials, thereby offering dual benefits of enhancing material properties and reducing environmental impact.

     Among plant par asitic nematodes, Meloidogyne (root-knot nematode) is one of the most economically important pests. The use of chemical nematicides is effective, however, can cause side effects on the environment and human health. For an environmentally friendly approach, the biocontrol methods are focused. This study aimed to evaluate the biological control of native Trichoderma spp. against Meloidogyne incognita (Kofoid and White) Chitwood. It was found that T. virens K1-02 and T. viride Z2-01 inhibited M. incognita egg-hatching by 71.7 and 73.4 %, respectively, and increased the mortality of juveniles by more than 80.0 % at 7 days post-inoculation under laboratory conditions. Regarding pot assays of the Sida tomato plant, both species exhibited the potential to inhibit gall formation and reproduction of M. incognita. Gall and egg mass index were lower in tomato roots treated with Trichoderma spp. than in untreated control. The reproduction factor (Rf) was 5.0 and 3.6 when treated by T. virens K1-02 and T. viride Z2-01, respectively while the untreated control was 12.3. These Trichoderma spp. did not affect tomato root length and plant height. The enzyme assays showed that both Trichoderma species could produce cuticle-degrading enzymes (chitinase and protease), whereas T. viride Z2-01 exhibited the highest activity of protease at 1.7 U/ml. In addition, it could be pointed out that the native Trichoderma isolates killed M. incognita before it invaded the tomato plant which correlated with the low activity of plant response enzymes, peroxidase (POD), and polyphenol oxidase (PPO) in tomato roots. The antagonist potentials of these Trichoderma species could lead to the development of bio-nematicide for controlling root-knot nematode disease.

     Bacterial leaf blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) impairs grain yield and is difficult to control. Therefore, we investigated the antibacterial activity of 100 bacterial isolates, obtained from plant tissues and agricultural soils, against Xoo strain E. Bacteria were grown in modified Wickerhams Antibiotic Test Medium (WATM), cell-free supernatants were collected, and their activity was evaluated using the agar well diffusion assay. The most inhibitory strain was TBRC 16324, isolated from Fragaria × ananassa roots, and its antimicrobial activity was further investigated. Ethyl acetate crude extracts were subjected to Sephadex LH-20 column chromatography followed by TCL-bioautographic assays. Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS) analysis of combined fraction 1 (with biological activity) showed that the pseudomolecular ion (m/z 1036.6919) closely matched the pseudomolecular ion of surfactin (m/z 1036.6928 [M + H]⁺). As the ethyl acetate crude extract was non-toxic to mammals using the L-929 mouse fibroblast assay, an in vivo experiment was undertaken. TBRC 16324 live cells and crude extract slightly reduced Xoo disease severity in Phitsanulok 2 rice seedlings in a screen-house. These findings suggest that TBRC 16324 may be a suitable candidate for further evaluation in field trials.

     Above-ground carbon at the stand level is often estimated from the combination of destructive and non-destructive methods using allometric equations. Today, terrestrial laser scanners provide three-dimensional (3D) data for forest structural assessments. We utilized the point clouds generated from light detection and ranging (LiDAR) to compute vegetation area index (VAI) and leaf area index (LAI), providing predictor variables besides the traditional above-ground carbon assessment. The stand above-ground carbon values of five forest plots were better using the VAI (R² = 0.66) than LAI (R² = 0.51) with the linear model fitting. However, the P-values are more than 0.05, which stands for no statistical significance. This study suggests scaling up to a large sample size and area, or downing the scale into individual trees that will promote better estimation of above-ground carbon in different forest types and conditions.

The glycemic index (GI) and glycemic load (GL) are important measures to assess the impact of foods and beverages on postprandial blood glucose levels. Accurate assessment of glycemic response ensures that products meet the nutritional needs of consumers who want an effective supplement without causing a spike in blood sugar levels. Consequently, the GI and GL of MARES P10, a whey protein beverage, are the objective of this study. The GI value of MARES P10 was determined in 10 healthy adults with an equal proportion of males and females. The blood glucose levels of participants were monitored for the subsequent two hours, and both the reference food (glucose solution) and MARES P10 contained 50 g of available carbohydrates. After ingesting MARES P10, participants had significantly lower blood glucose levels than after oral glucose solution test at 15, 30, 45, 60, and 90 minutes (p<0.001, <0.001, <0.001, <0.001, and 0.039, respectively). The incremental area under the glycemic response curve at 120 minutes was also significantly lower than that of the oral glucose solution test (1,589.60 ± 217.14 and 4,725.60 ± 354.12 mg × min/dL, respectively, p<0.001). The GI and GL of MARES P10 were analyzed, and the mean ± SEM values were 34.56 ± 4.81 and 13.91 ± 1.94, respectively. These findings suggest that MARES P10 has a low GI and a medium GL, making it a suitable supplement for individuals seeking to manage blood sugar levels and maintain sustained energy.

     Lithium-ion batteries (LIBs) are chemically reactive rechargeable energy storages. Silica (SiO₂) is one of the most popular alternative materials to replace graphite as an anode material in LIBs due to its higher specific capacity, non-toxicity, and natural resources. Streblus asper Lour. (Khoi) is widely grown in Southeast Asia and contains high SiO₂ and SiO₂/C levels in its leaves. In order to overcome the volume change issue of Si-based materials and enhance cycle stability, carbon (C) and polypyrrole (PPy) were utilized to reinforce the SiO₂ structure during the lithiation/delithiation process. X-ray diffraction (XRD) was utilized to investigate the SiO₂, C, and PPy amorphous phases of the synthesized products. Fourier transform infrared spectroscopy (FT-IR), which confirmed the formation of PPy in composites. The scanning electron microscopy (SEM) images revealed different morphologies of SiO₂ aggregates, SiO₂/C with plate layers, the network structure of PPy and in the composites with PPy. Transmission electron microscopy (TEM) revealed the aggregation of nano-sized SiO₂, SAED phase confirmation, and demonstrated the coating of PPy on SiO₂/C (KSCPy composites), indicating the presence of C and PPy as supporters. In addition, the performance of synthesized composites as anodes was investigated by assembling them into half-coin cells and performing electrochemical tests. Khoi-SiO₂/C/PPy (KSCPy) obtained a specific capacity of 497.9 mA g⁻¹ for 400 cycles at 0.1 A g⁻¹ and the lowest charge transfer resistance. Furthermore, these materials have the potential to be used as sustainable anode materials in LIBs due to their use of natural materials, a non-toxic synthesis method, and C and PPy as both support materials and conductive polymers, which can enhance electrical performance as anode materials.