ASEAN Journal of Scientific and Technological Reports

Detection and Measurement of Natural and Anthropogenic Disturbances in a Protected Area Using the Rasch Model

Mark Anthony C. Abella — 2026-02-27

This study aimed to assess the extent of major threats in the 244.13-hectare Tugbo Natural Biotic Area (TNBA) on Masbate Island, Philippines. Threat-focused patrolling has covered the entire continuum, with a specified recording interval along the protected area (PA), divided into numerous patrol routes. Categorized into human-induced and natural calamities, a total of 27 individual threats were geo-tagged and recorded, with mixed perennial farming as the most frequent threat. Using geo-spatial technologies, the risks were reduced to 10, largely represented by broad expanses of rangelands and invasive monocrop plantations. This paper presents a new methodology for measuring and visualizing threats to protected areas based on the Rasch model. This probabilistic analysis is based on the presence or absence of the threat in each location, disturbance estimates, and the calculation of misfits. The visualization map illustrates that the protected area had an unequal distribution of threats. Most locations have less disturbed areas; hence, the data indicate that the protected area is nearly pristine. This approach is a useful methodology for assessing in-depth environmental disturbance.

Comparison of Inhibitory Effects between Cetuximab and Cisplatin on Colon Cancer SW480 Cell Line

Barakat Abdulrazzaq Mutar — 2026-02-27

Cancer is still one of the more severe diseases that endangers the life of a human being, especially in the present day. Globally, colorectal cancer is a very predominant cancer and the second principal contributor to cancer-related fatalities across all ages, both adults and children. Currently available treatments include surgery, radiotherapy, chemotherapy, and immunotherapy. Chemotherapy is an established modality in the therapy of cancer, and platinum-based drugs demonstrated activity against several tumours. Here, cancer cell lines were grown in ELISA plates in media until ~80% monolayer confluence. Cetuximab (Cetx) was tested for cytotoxicity on the SW480 colon cancer cell line at six serial concentrations ranging from 2.5 to 0.0781 µg/mL. Similarly, the same cell line was exposed to six serial levels of cisplatin (Cisp.), varying from 100 to 3.125 µg/mL, for 24 hours. Cells without any treatment served as controls. Cell viability was monitored by measuring OD with an ELISA reader after staining with crystal violet. The findings revealed a significant result at the statistical level (P < 0.05). in the cell-killing impacts of cetuximab and cisplatin in colon cancer cells. These findings emphasize the potential value of cetuximab's anti-tumour activity when used alongside traditional platinum-based chemotherapy and support its use in targeted cancer therapy.

Rhodocista sp. Strain SAIYAI: A Natural Source of Spirilloxanthin and Feed Attractability in Pacific White Shrimp (Litopenaeus vannamei)

Agnesia Frisca Damayanti — 2026-02-27

This study investigated the potential of isolated photosynthetic bacteria (PSB) as carotenoid producers and assessed their efficacy as a low-cost functional feed additive for Pacific white shrimp (Litopenaeus vannamei). Fifteen PSB isolates representing 3 color groups, red, orange, and yellow, were evaluated for total carotenoid content (TCC), and the highest TCC-producing PSB were RP22-4-DPM with 0.82 ± 0.07 mg/g of DW, RP22-OR with 0.38 ± 0.03 mg/g of DW, and RS22-YB with 0.47 ± 0.07 mg/g of DW, respectively. Isolate RP22-4-DPM, further designated as PSB strain SAIYAI, exhibited the highest DPPH scavenging activity (72.65 ± 4.60%) (p<0.05); meanwhile, its ABTS scavenging activity (70.7 ± 2.73%) showed no significant difference compared to other strains (p>0.05). The predominant pigment and the major carotenoid of this strain were identified as spirilloxanthin by UV-Vis spectrophotometry and APCI LC/MS. Additionally, the attractability was evaluated by coating soybean meal with the lyophilized cell and culture media of the SAIYAI strain at 0.5%, 1%, and 1.5% to Pacific white shrimp. All concentrations significantly increased feed attractability compared to non-coated soybean meal (p<0.05), while 0.5% and 1.0% exhibited similar attractability (p>0.05). Molecular identification through 16S rRNA sequence analysis and phylogenetic tree construction suggested that strain SAIYAI belongs to the genus Rhodocista, which is closely related to Rhodocista xerospirillum and Rhodospirillum centenum. Accordingly, this study provides evidence that Rhodocista sp. strain SAIYAI is a potent spirilloxanthin producer with antioxidant properties and potential as a multifunctional, cost-effective attractant in shrimp feed.

Process Parameter Optimization of Ti-45Nb Titanium Alloy Produced Using the Design of Experiments Technique

Bo Liang — 2026-02-27

The goal of this study is to optimize the production conditions of Ti-45Nb titanium alloy by innovatively introducing the Design of Experiments (DOE) method and using the 2^k method of full factor analysis in DOE, and to improve the chemical heterogeneity of Ti-45Nb titanium alloy by analyzing and optimizing the parameter conditions of the production process and a total of 32 experiments was conducted. Ti-45Nb titanium alloy was produced by vacuum arc remelting (VAR) according to the following process parameters. The titanium alloy products obtained from each production were cut into circular samples with a diameter of 16 cm, and the chemical inhomogeneity was measured by Energy-dispersive X-ray spectroscopy using the 5-point sampling method. Then, the chemical inhomogeneity data values were entered into the previous experimental design, and the appropriate factor levels were determined using the technology provided in the Minitab statistical software package, with a significance level of 0.05 (α = 0.05). Through full factorial design (DOE) and residual analysis, a regression model for chemical inhomogeneity was successfully constructed. After optimization, the production conditions of Ti-45Nb titanium alloy are: Smelting current (KA) = 1.7, Current coil (A) = 3.2542, Transform time (S) = 6, Inlet water temperature (°C) = 25, and Water flow (L/min) = 220. The chemical inhomogeneity value of the produced Ti-45Nb titanium alloy is theoretically 10%. It can provide a reference for enterprise production.

Humanitarian Logistics Modelling for Flood Disaster Management in Thailand

Rojanee Homchalee — 2026-02-27

Nowadays, many areas in Thailand have experienced severe flood disasters that have widespread effects on life, property, society, economy, and the environment. Therefore, this research aims to develop a mathematical model for humanitarian logistics management in Thailand's flood-affected areas. Two models were developed using mixed-integer nonlinear programming: one to minimize the total cost of disaster relief management, and another to maximize the number of rescued disaster victims, with operating costs as a constraint, because in some situations there was a limited budget for helping victims. The two proposed models provided disaster preparedness planning by identifying optimal shelter locations, determining appropriate quantities of relief supplies to procure, and allocating and distributing those supplies efficiently to affected victims.

Physicochemical Properties of Carrageenan Extracted from Raw Dried Seaweed of Caluya, Antique, Philippines

Julie Ann Arcales-Quinal — 2026-02-27

Marine hydrocolloids, such as carrageenan extracted from seaweeds, are widely used in food, industrial, and commercial applications. The Philippines has great potential to export carrageenan, but the industry requires strict quality regulations for the product. The specifications for raw dried seaweeds (RDS), including chemical and gel rheological properties, of Eucheuma denticulatum “Milyon milyon” and Kappaphycus striatum “Sacol”, collected from Caluya, Antique, Philippines, were investigated and compared to the national standards used by the carrageenan production industry. The RDS (moisture, ash, clean anhydrous weed, impurities) of E. denticulatum and K. striatum were within the limits of the Philippine National Standards. The chemical properties (moisture, ash, acid-insoluble ash, and sulfate content) of carrageenan extracted from E. denticulatum were within the standards, except for the acid-insoluble ash and sulfate content of K. striatum, which exceeded the limit. On the other hand, the rheological properties of carrageenan, including gel viscosity, gelling and melting temperatures, and hysteresis, were also within the standard limits. The study suggests using RDS from E. denticulatum to produce carrageenan, as it complies with the Philippine National Standards utilized by the seaweed industry.

Berberine Ameliorates Methionine-Induced Hyperhomocysteinemia and Biochemical Alterations in Male Rats

Aula Talib Zahwar — 2026-02-27

Hyperhomocysteinemia, characterized by elevated plasma homocysteine levels, is associated with oxidative stress and metabolic dysfunction. This study evaluated the protective effects of berberine, a natural alkaloid compound, against methionine-induced biochemical alterations in male rats. Thirty-two adult male albino rats were randomly divided into four groups (n=8 each) and treated orally for eight weeks: Group 1 (negative control) received standard diet and water; Group 2 (positive control) received methionine (100 mg/kg); Group 3 received methionine (100 mg/kg) plus berberine (40 mg/kg); and Group 4 received berberine (40 mg/kg) alone. Serum samples were analyzed for homocysteine (Hcy), electrolytes (sodium, potassium, chloride), and creatine phosphokinase (CPK) enzyme activity. Methionine treatment significantly elevated homocysteine and CPK levels while reducing sodium and chloride concentrations compared to controls. Co-administration of berberine with methionine markedly decreased homocysteine levels from 76.5 to 12.2 micromole/L and normalized CPK activity. Berberine also restored sodium and chloride concentrations to near-normal levels. The berberine-only group exhibited biochemical parameters comparable to the negative control, confirming its safety profile. These findings demonstrate that berberine effectively mitigates methionine-induced biochemical disturbances through multiple mechanisms, including antioxidant effects, activation of the AMPK pathway, and reduction of reactive oxygen species. Berberine also protected electrolyte homeostasis and mitochondrial function. Therefore, berberine represents a promising natural therapeutic agent for preventing oxidative stress and metabolic complications associated with hyperhomocysteinemia, with potential applications in clinical management of homocysteine-related disorders.

Effect of Recycled Coarse Aggregate Quality on Compressive Strength of Concrete at Different Replacement Levels

Arusmalem Ginting — 2026-02-27

Recycled Coarse Aggregate (RCA) is produced from the processing of construction and demolition waste and is used as a replacement for Natural Coarse Aggregate (NCA). Waste concrete cylinders from compressive-strength testing in precast concrete factories are readily available but have not been optimally utilized. One potential solution for utilizing this waste is to recycle it into RCA. In previous studies, the quality of the RCA used was generally not known with certainty; therefore, its effect on Recycled Aggregate Concrete (RAC) remains to be further investigated. This study aims to determine the effect of RCA quality on the compressive strength of new concrete. The RCA used in this research consists of six quality levels: RCA67 (f'c = 67 MPa), RCA58 (f'c = 58 MPa), RCA50 (f'c = 50 MPa), RCA30 (f'c = 30 MPa), RCA25 (f'c = 25 MPa), and RCA20 (f'c = 20 MPa). NCA was replaced with RCA at two replacement levels: 50% and 100%. The tests included aggregate properties, slump, compressive strength, and unit weight. The results showed that the compressive strength of Natural Aggregate Concrete (NAC) with 100% NCA was higher than that of RAC with either 50% or 100% RCA. Compared to NAC, the compressive strength of RAC decreased by 14.11%–43.58% with 100% RCA and by 1.53%–13.75% with 50% RCA. The compressive strength of RAC decreased as the quality of RCA decreased. RCA quality had a significant effect on concrete compressive strength at both replacement levels.

An IoT-Based Real-Time Human Fall Detection and Notification System with Instance Segmentation Deep Learning

Wiwat Su-hren1 — 2026-02-27

This research presents a person fall detection system based on deep learning using the Instance Image Segmentation technique with the YOLOv11-seg model, which achieves high speed and accuracy in object detection. The developed system aims to individually detect a person's posture in an image, enabling accurate analysis of their falling posture characteristics. And there is a notification in the application to the administrator or relevant person within 10 seconds, allowing quick help. Using a dataset of 10,169 images, 8622 for training, 994 for inspection, and 553 for testing (with a ratio of 85:10:5 for training, inspection, and testing). The system performs impressively by using all 3 YOLOv11-seg models: YOLOv11s-seg, YOLOv11n-seg, and YOLOv11m-seg. The training dataset showed excellent performance with a YOLOv11s-seg model, achieving a precision of 0.966, a recall of 0.910, and an F1 Score of 0.88. The results show that the developed system can detect falls and issue real-time alerts via an IoT-based framework. It improves safety and reduces the risk for the elderly or patients at risk of falling.

Deep Learning-Based Classification of Apple Leaf Diseases under Field Conditions

Supakit Mamart — 2026-02-28

Accurate identification of apple leaf diseases in field conditions is essential for sustaining crop yield and supporting precision agriculture. Variable illumination, cluttered backgrounds, and co-occurring symptoms complicate diagnosis in real orchards. This study applies a deep learning approach using a fine-tuned MobileNetV2 model to classify apple leaf diseases from a heterogeneous dataset derived from the Plant Pathology 2021 (FGVC8) benchmark. The original five labels were expanded by subdividing the "multiple disease" category into expert-defined compound subclasses, yielding 12 disease categories encompassing both single and compound infections. Data augmentation and transfer learning were employed to improve robustness, while interpretability was assessed through Grad-CAM and LIME visualizations. Results show that the model performs well on distinct single-disease categories such as rust, scab, and frogeye leaf spot, but struggles to detect overlapping or compound infections. These findings highlight both the potential and the challenges of lightweight CNN architectures for agricultural image classification. The study contributes evidence that explainable, compact deep learning models can support future efforts to build reliable tools for plant health monitoring in diverse field conditions.

Data-Driven Design of an Automatic Shower for the Elderly: Integrating the Kano Model and K-Means Clustering

Rattawut Vongvit — 2026-02-28

Automated devices designed for elderly users have become increasingly important in supporting independent living and addressing age-related challenges. Among these technologies, automatic shower devices play a key role in enhancing personal hygiene and reducing safety risks associated with conventional showering. This study applied the Kano model to identify factors influencing customer satisfaction with an automated shower device designed for older adults. Expert input was used to define and evaluate 25 quality elements across six dimensions, including washing, cleaning, safety, customer service, product-friendliness, and software–hardware integration. The results indicate that safety- and cleaning-related features—such as automatic disinfection, machine self-cleaning, automated emergency calls, emergency stop functions, and fall detection—exhibit high satisfaction coefficients, highlighting their importance in meeting elderly users’ expectations. To further explore variation in user preferences, K-means clustering was used to segment respondents based on their Kano response patterns. Three distinct user clusters were identified, each demonstrating different feature prioritization strategies. One cluster emphasized comfort-enhancing features, such as body massage and automatic warm-air drying, while another placed greater importance on essential safety functions, including fall detection and emergency alerts. By integrating the Kano model with K-Means clustering, this study proposes a data-driven, customer-centric design framework that supports informed decision-making in assistive technology development. The findings enable designers and manufacturers to balance core safety requirements with differentiated features tailored to diverse elderly user segments, ultimately enhancing usability, independence, and overall user satisfaction.

The combination of different carriers in producing plant-based seasoning powder from oyster mushroom (Pleurotus sajor-caju)

Nguyen Thi Ngoc Giang — 2026-02-28

The increasing popularity and prioritization of plant-based nutritional foods have heightened the focus on research and the diversification of plant-derived products. Therefore, this paper centers on producing a plant-based seasoning powder from oyster mushroom, an available commodity, using its concentrated extract and various carriers to maximize retention of bioactive nutrients and ensure compliance with the product's physicochemical and microbiological quality standards. The optimal ratio of the combination between maltodextrin (MD) and gum arabic (GA) was obtained through a range of investigated ratios, which was a completely randomized setup with concentrations of 5, 10, 15, and 20% for MD, and 0, 0.5, 1.0, 1.5, and 2% for GA. The outcome has shown that MD combined with GA significantly affected the seasoning powder product; at a mixing ratio of 10% MD and 1% GA, it exhibited the highest stability and optimal physicochemical properties. The high retention of key bioactive compounds, including flavonoids, phenolics, lysine, glutamic acid, and β-glucan, with respective contents of 0.0034 g QE, 0.28 g TAE, 0.0052 mg, 2.32 mg, and 10.86 mg per 100 g dry matter. The powder demonstrated satisfactory yield and solubility, and the brightness index was the highest among all tested formulations. Moreover, the water activity reached 0.42, ensuring the product's enzymatic and microbiological stability.

Service Life Prediction of Natural Rubber/Reclaimed Rubber Blends through Thermogravimetric Analysis

Sutiwat Thumrat — 2026-02-28

The rubber products containing reclaimed rubber may have influenced the service life due to their prior degradation history. However, not many rubber compounders know their service life until they have used it for a certain period. This study breaks this barrier by proposing a simple, cost-effective prediction method based on thermogravimetric analysis (TGA). It focused on blends of Natural Rubber (NR) and Reclaimed Rubber (RR) at various blending ratios. The Ozawa–Flynn–Wall (OFW) Method was applied to the TGA outputs. The results showed that NR/RR blends at all ratios had slightly lower lifetimes than virgin NR over the temperature range of 30-600 °C. When considering a service temperature of 70 °C, the use of RR at 50 phr could reduce the service life from 195 years to 2.01 years. This indicates that the addition of RR may severely affect the service life of the products. The results of this study are useful information for rubber compounders when using RR in their formulations.

Electron Spin Resonance (ESR) Signal Analysis of Fossil Teeth from Mae Moh Mine, Thailand

Tidarut Vichaidid — 2026-02-28

This study investigates the characteristics of Electron Spin Resonance (ESR) signals in fossil tooth enamel collected from the Mae Moh lignite mine in Lampang Province, Thailand. ESR spectra were recorded at room temperature (298 K) using a Bruker EMX Premium spectrometer operating at X-band (9.85 GHz) with a modulation frequency of 100 kHz and a modulation amplitude of 0.3 mT. The most prominent signal was observed at g ≈ 2.002, attributable to trapped carbonate radicals within the hydroxyapatite crystal lattice. By applying the Multiple-Aliquot Additive Dose (MAAD) protocol, the ESR intensity at g ≈ 2.002 exhibited a strong linear relationship with laboratory-administered gamma doses (0–2000 Gy), yielding a dose-response slope of 0.2185 a.u./Gy (R² = 0.907). From this calibration, the natural accumulated dose for the fossil teeth was determined to be 550 ± 30 Gy. These findings demonstrate the reliability of ESR signal analysis for quantifying accumulated radiation dose in fossil enamel and support its application for future geochronological investigations in the Mae Moh basin.

Conflict Victimization Model in Southern Thailand: An Event-Level Analysis Using Multinomial Logistic Regression

Abdunfatah Masamae — 2026-02-28

This study investigates the determinants of conflict-related victimization severity in Thailand’s southernmost provinces using event-level data from 9,310 southern unrest incidents recorded between 2004 and 2020. Victimization outcomes were classified into three ordered severity categories—safe, injured, and dead—and analyzed using Multinomial Logistic Regression (MLR) to capture differentiated risk mechanisms. The dataset, compiled by the Deep South Coordination Center (DSCC), integrates police, military, and administrative records to provide comprehensive coverage of subnational conflict events. Feature selection was conducted using chi-squared screening followed by backward refinement, yielding nine key predictors encompassing temporal, spatial, contextual, and tactical dimensions. Model estimation was performed under both baseline and imbalance-adjusted weighted specifications, with robustness assessed through cross-validation and sensitivity analyses. Results indicate that non-residential locations, particularly public places, roads, and agricultural areas, substantially increase the likelihood of injury and fatal outcomes. At the same time, rural settings are associated with lower severity risk, and attacks targeting military personnel exhibit markedly elevated injury and fatality odds relative to civilian targets. Shooting attacks emerge as the most lethal modality, with an estimated 15.8-fold increase in fatal risk compared to bombings. Predictive evaluation demonstrates strong discrimination for safe outcomes (AUC = 0.94), with good to moderate performance for injury (AUC = 0.80) and fatal events (AUC = 0.75). The findings highlight the dominant roles of spatial context and attack modality in shaping victimization severity and demonstrate the value of interpretable statistical modeling for informing targeted security planning and conflict-prevention strategies.

An Academic Extension-Driven Solution for Enhancing Local Governance

Dawn Iris Calibo-Senit — 2026-02-28

Despite the rise of the e-governance agenda in supporting local government operations, the involvement of higher education in promoting a collaborative extension initiative supporting such an agenda remains scarce in the literature, especially in rural communities with low digital literacy. Thus, this work details the development and implementation of the Cangbagsa Digital Barangay Information System (CDBIS), an academically driven extension solution that addresses inefficiencies in barangay (i.e., the Philippines’ smallest administrative unit) operations. Prior challenges included processing documents within 2–3 days, data inaccuracies, and limited service accessibility. This study aims to digitize local governance, improve efficiency, ensure data integrity, and create a scalable model for community innovation. The system was developed using a web-based, multi-tier architecture that integrates a user-friendly interface, role-based business logic, a centralized database, and secure server infrastructure to support efficient barangay data management and decision-making. The post-implementation evaluation uses the Updated DeLone and McLean Information System Success Model and a 22-item survey for system users, using a 7-point Likert scale. Data from the survey were analyzed through descriptive statistics and stepwise regression to identify predictors of user satisfaction. Respondents rated all constructs highly. Regression analysis shows System Quality as the strongest predictor of satisfaction (β=0.361), followed by Service (β=0.295) and Information Quality (β=0.287), explaining 65% of the variance. CDBIS significantly improved governance, reducing processing time by 75% and improving data accuracy by 88%. Sustaining success requires ongoing optimization, training, and user engagement. The system offers a replicable model for digital transformation in other rural communities.

Impact of Marine Fish Amino Acid on Yield Parameters and Preventive Antioxidant in Okra

Nopparat Tatmala — 2026-03-01

A field experiment was carried out to evaluate the effects of foliar-applied marine fish amino acids (MFA) on the growth, yield, yield components, and preventive antioxidant capacity of okra, as well as the interaction between okra varieties and MFA concentrations. The study used a split-plot design with four replications. Three okra varieties — RED FINGER, KN–OYV–02, and LUCKY FILE 473 — were assigned to main plots. Five concentrations were tested in the subplots (0.00, 1.50, 3.00, 4.50, and 6.00 ml/l). Yield per plant — a key indicator for growers — did not differ significantly among the three varieties but responded to MFA levels-plants treated with 3.00, 4.50, or 6.00 ml/l. MFA showed no significant differences among these higher concentrations; however, all produced higher yields than the untreated control and the 1.50 ml/l treatment. The greatest yield (1,271.49 g/plant) was obtained at 3.00 ml/l, followed by 4.50 ml/l (1,251.22 g/plant) and 6.00 ml/l (1,215.51 g/plant). Reducing sugar content did not vary significantly among the okra varieties but was influenced by MFA levels. LUCKY FILE 473 recorded the highest reducing sugar (~1.77 mg/ml). The concentrations 3.00, 4.50, and 6.00 ml/l yielded the highest reducing sugar levels (1.89, 1.84, and 1.77 mg/ml, respectively), with no significant difference among them, while the control plants had the lowest value (1.53 mg/ml). Among pigment traits, RED FINGER exhibited the lowest chlorophyll a, chlorophyll b, and total chlorophyll contents (2.96, 1.51, and 4.47 mg/g FW, respectively) but had the highest carotenoid concentration (0.50 µg/g FW).

A Comprehensive Literature Review on Greenhouse Gas Mitigation in Thailand’s Building and Industrial Sectors: Technical, Economic, and Policy Insights from Recent Studies

Jirawong Siribrahmanakul — 2026-03-01

This scoping review examines greenhouse gas (GHG) mitigation options in Thailand's industrial and building sectors, synthesizing findings from 26 peer-reviewed articles and five national policy documents. The review is structured around three themes: technical viability, financial performance, and policy alignment of key mitigation strategies. Results indicate that energy-efficiency retrofitting, renewable energy integration, carbon capture and storage (CCS), and life-cycle assessment (LCA)-guided design — particularly when combined with Building Information Modeling (BIM) — can substantially reduce both operational and embodied emissions. Many of these approaches demonstrate strong financial attractiveness, characterized by high internal rates of return (IRR) and short payback periods. However, widespread deployment remains constrained by policy fragmentation, insufficient incentive mechanisms, and weak stakeholder coordination. The review also exposes critical gaps in sectoral strategies, including the absence of tailored energy conservation measures for certain building typologies. The limited uptake of local green certification schemes, such as TREES, which cover fewer than 15% of certified green buildings nationwide, further reflects structural barriers in Thailand's regulatory and market environments. To address these challenges, this study proposes a sectoral strategy matrix that maps appropriate technologies to specific building types alongside relevant economic indicators. It also recommends harmonizing existing frameworks — EEP2015, AEDP2015, and BEC2021 — with Thailand's 2022 Nationally Determined Contribution (NDC) and Long-Term Low Emissions Development Strategy (LT-LEDS). Future research should explore integrated models incorporating ESG criteria, stakeholder capacity-building, and carbon tracking linked to Science-Based Targets (SBTs). By bridging technical rigor with policy relevance, this review offers actionable guidance for researchers, policymakers, and industry practitioners.

Acid Tolerance Response in Streptococcus mutans Biofilms: Role of Membrane Lipid Adaptations and ATPase Activity

Aqeel Shanan Omran — 2026-03-02

Streptococcus mutans is one of the main etiological factors of dental caries since it has an exceptional capacity for surviving and growing in acidic conditions in the mouth. Nevertheless, its cellular mechanisms of acid tolerance are not fully comprehended. This paper investigated the functions of membrane lipid remodeling and proton ATPase activity in the acid tolerance response (ATR) of S. mutans biofilms. The biofilms were cultivated in a flow-cell system and subjected to lethal (pH 3.5) or sub-lethal (pH 5.5) conditions after 3 hours, with neutral pH (7.5) as a control. Viable counts on blood agar were performed over a 2-hour exposure to determine cell survival. Pre-adaptation to pH 5.5 significantly improved survival at pH 3.5, with 66% survival recorded versus 1% in non-adapted biofilms. The fluorescence microscopy showed an increase in biofilm structural integrity after adaptation to acid. Lipid analysis of the membranes showed that there were significant changes in the fatty acid composition, with increases in the percentages of monounsaturated and long-chain fatty acids under sub-lethal acidic stress. Simultaneously, membrane-bound proton ATPase activity increased, facilitating cytoplasmic pH homeostasis by increasing proton extrusion. A combination of these adaptive responses will ensure the survival of bacteria in recurrent acidic challenges by safeguarding acid-sensitive intracellular elements. The results enhance the knowledge of S. mutans virulence and resistance.

Nitrogen Uptake at Different Growth Stages of Corn and Its Effect on Important Yield Parameters

Melissa I. Canunayon — 2026-03-02

Nitrogen is the primary nutrient governing corn yield. This study compares the contrasting nitrogen dynamics of open-pollinated (OPV) and hybrid corn varieties and their consequential impact on overall yield. However, limited research exists comparatively evaluating the nitrogen uptake and utilization efficiency of these varieties under uniform fertilization rates across distinct growth stages. The study employed a Randomized Complete Block Design (RCBD) with three replications, and all treatment plots received the same fertilizer rate to guarantee unbiased experimental results. All collected data were analyzed using the Statistical Package for the Social Sciences (SPSS) and the Statistical Tool for Agricultural Research (STAR) software. These analyses include One-way Analysis of Variance, Independent Sample T-tests, and Pearson's correlation. The results show that nitrogen uptake in hybrid corn declined gradually and steadily across all growth stages (V8: 3.17%, R1: 2.92%, R3: 2.88%, and R5: 2.27%), contrasting with the fluctuating absorption pattern of the OPV. This superior N management is supported by Nitrogen Utilization Efficiency (NUtE), in which the hybrid (31.55 ± 1.36) achieved a higher NUtE than the OPV (28.09 ± 1.38). The two varieties exhibited a statistically significant difference in N uptake at the R1 stage (p = 0.048), with the hybrid maintaining a higher N concentration (2.92%) than the OPV (2.58%). Interestingly, OPV N uptake at R1 exhibited a strong correlation with kernel weight (0.638), unshelled weight (0.676), ear weight (0.643), and grain yield (0.576), but showed the inverse trend for hybrid corn. These contrasting results confirm that the OPV exhibits lower nitrogen uptake efficiency while the hybrid displays rapid nitrogen absorption, necessitating precision, variety-specific fertilization strategies for yield and environmental stewardship.