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A magnetic nanosensor for flammable VOCs detection: unveiling Mn2SO2 monolayer performance through ab initio modelling
(2026-06-30)
Oo, Ghaim Man
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Khammuang, Satchakorn
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Udomkijmongkol, Anan
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Thasitha, Sirinee
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Ounrit, Iyarat
Effective victim detection during fire disasters requires reliable identification of flammable VOCs under high-temperature conditions. Magnetic VOC sensors based on two-dimensional nanomaterials offer a promising solution. In this work, a Mn<inf>2</inf>SO<inf>2</inf> monolayer is investigated as a magnetic VOC sensor for eleven fire-related VOCs using density functional theory (DFT). Mn<inf>2</inf>SO<inf>2</inf> exhibits intrinsic spin polarization and ferromagnetism that support magnetic sensing. Adsorption results show strong chemisorption for Benzaldehyde, Butanol, Heptane, Hexanal, Methylamine, Dimethyl disulfide, Dimethyl trisulfide, Pyridine, and Toluene, with adsorption energies from −1.53 to −0.46 eV, whereas Butanone (−0.34 eV) and Octane (−0.12 eV) show weak physisorption. Charge transfer, electron density difference, and ELF analyses reveal predominantly ionic interactions, with Mn<inf>2</inf>SO<inf>2</inf> acting as an electron acceptor. Sensor responsiveness assessed via work-function modulation and magnetic-moment variation indicates high sensitivity, particularly for Pyridine (42.81%), Dimethyl disulfide (33.07%), Butanol (15.57%), and Toluene (15.84%). Ab initio molecular dynamics at 400 K confirm thermal stability and structural integrity on the picosecond timescale. Pyridine and Dimethyl disulfide emerge as the most promising detection targets due to high sensitivity and fast recovery times. These results highlight Mn<inf>2</inf>SO<inf>2</inf> as a promising candidate for the future generation of magnetic VOC sensors in fire-disaster victim detection.
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Mechanistic understanding of transition-metal-decorated biphenylene for highly selective NO2 and NH3 detection
(2026-06-15)
Wongphen, Kantaphong
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Khammuang, Satchakorn
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Oo, Ghaim Man
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Hussain, Tanveer
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Kotmool, Komsilp
Here, we employ density functional theory (DFT) in combination with ab initio molecular dynamics (AIMD) simulations to examine the sensing performance of biphenylene doped with selected transition-metal dopants (M@BP), specifically Fe, Co, and Ni, on NO<inf>2</inf> and NH<inf>3</inf>. The results indicate that NO<inf>2</inf> exhibits stronger interaction than NH<inf>3</inf>, with adsorption energies ( E<inf>ads</inf> ) exceeding -3.0 eV. In contrast, the E<inf>ads</inf> values for NH<inf>3</inf> are around -1.30 eV. Bader charge and electron density difference (EDD) analyses reveal that charge is transferred from the M@BP monolayers to NO<inf>2</inf>. In contrast, the charge transfer occurs in the opposite direction for NH<inf>3</inf>, indicating distinct chemical adsorption mechanisms. Additionally, the electron localization function (ELF) results indicate partial ionic bonding and localized charge sharing between the metal sites of M@BP and the gas molecules. Variations in the work function, alongside calculated sensitivity (S) values, demonstrate that M@BP is exceptionally responsive to NH<inf>3</inf>, with S values of 13.4 %, 8.7 %, and 13.7 % for Fe@BP, Co@BP, and Ni@BP, respectively. These materials exhibit strong potential as reusable gas sensors capable of operating at temperatures above 500 K while maintaining practical recovery times. Moreover, AIMD simulations confirm the thermal stability of Co@BP and Ni@BP, whereas Fe@BP exhibits instability at 600 K. These findings suggest that M@BP possess a strong affinity for NH<inf>3</inf>, tunable electronic properties, and excellent thermal stability, making them promising candidates for selective, reusable high-temperature gas-sensor applications.
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Airborne Dental Material Particulates and Occupational Exposure: Computational and Field Insights into Airflow Dynamics and Control Strategies
(2025-11-01)
Chanbandit, Chanapat
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Kanchanatawewat, Kanchana
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Oo, Ghaim Man
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Thongsri, Jatuporn
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Tuntiwong, Kuson
Occupational exposure to airborne polymethacrylate (PMMA) particles during dental laboratory procedures poses an underexplored health risk. This study presents the first integrated Computational Fluid Dynamics (CFD) and real-time particle monitoring investigation of 0.5 µm PMMA particle dispersion during mechanical polishing in an actual clinic. We quantitatively assessed particle behavior in 30 s exposure scenarios by examining the effects of dental professional work orientations and comparing two mitigation strategies, rear-inlet portable air cleaners (PACs) and a Box Dust Collector (BC), with an emphasis on the safety of both personnel and patients. The findings establish that operatory airflow is a primary safety determinant: aligning the workflow with the main airflow (0°). Furthermore, the combined use of PACs and BC demonstrated synergistic superiority, achieving the optimal reduction in peak concentrations and airborne residence time. PACs alone reduced working zone concentrations by up to 80%, while BC provided a crucial 40–60 s delay in initial plume dispersion. We conclude that effective exposure control requires a proactive, two-stage engineering defense: source confinement augmented by continuous ambient filtration. This research provides a robust, evidence-based foundation for defining airflow-aware ergonomic and combined engineering standards in the evolving digital era of dentistry.
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Analysis of Indoor PM2.5 Contaminants Based on Outdoor Wind Velocity Through Different Infiltration Types
(2025-01-01)
Oo, Ghaim Man
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Kotmool, Komsilp
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Mongkolwongrojn, Mongkol
Nowadays, indoor PM2.5 concentrations have become a significant factor affecting indoor air quality (IAQ) and a major public concern, particularly with the rise of haze in Thailand and globally, as PM2.5 can penetrate human lungs. This research analyzes the dispersion of PM2.5 from outdoors to indoors using a fluid dynamics simulation framework that combines the Eulerian approach for continuous flow, the Lagrangian approach for particulate matter dispersion, and the RNG k-ε turbulent model for airflow. The study is aimed at protecting indoor environments from harmful exposure to PM2.5 from outdoor contaminants and improving IAQ. Primarily, three different infiltration types and shapes are studied to determine the minimum optimal positive room pressure, based on the impact of ambient wind velocity on indoor PM2.5 concentrations from outdoor pollutants. A minimum optimal pressure of 3.6 Pa and 27 air changes per hour (ACH) is sufficient to achieve a PM2.5-free indoor environment for all infiltration models. Furthermore, higher wind speeds can reduce indoor PM2.5 concentrations due to the increased momentum of particles. This research technique is implemented in the practical field study conducted within the laboratory room of the 55-Year Chalermprakiat Building. As a result, the investigated room, with an infiltration area of 0.06 m<sup>2</sup> and a rate of 0.0036 m<sup>3</sup>/s, will be certified as a clean room by achieving an optimal minimum pressure of approximately 0.01 Pa. This research will help achieve cleaner and safer indoor environments for any building by leveraging the optimal minimum pressure of cleanroom technology, provided that the infiltration rate and ambient wind velocity are accurately determined.
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Case Study on the design optimization of the positive pressure operating room
(2024-12-01)
Oo, Ghaim Man
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Kotmool, Komsilp
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Mongkolwongrojn, Mongkol
Ventilation systems of operating rooms (ORs) are significantly important in preventing postoperative wound infections that can cause morbidity and mortality after surgery in or out of the hospital. This study aims to identify the optimum overpressure for efficient operation while reducing the risk of surgical site infections (SSIs) based on the actual OR with the help of computational fluid dynamics. The species transport model, Lagrangian discrete phase model, and turbulent standard k-ε model are mainly used for the transient numerical study to improve the performance of the OR and reduce SSI cases. Four OR schemes were initially calculated for the best location of the patient on the surgical table. The results revealed that the modified position 90˚ is the best location with the minimum CO<inf>2</inf> and BCP concentrations. The investigated operating room could host up to ten surgical members with the optimum overpressure of 5.89 Pa and 0.56 m/s of supply velocity under the standard cleanliness level. Modifying the supply surface area will enhance the performance of the operating room by providing a cleaner zone and maintaining the desired room pressure, even with a low airflow rate. This optimization scheme could guide practical applications in all positively pressurized operating rooms to address issues related to overpressure effects.
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Analysis of parametric optimization on the design of negative pressure room
(2023-01-01)
Oo, Ghaim Man
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Kotmool, Komsilp
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Mongkolwongrojn, Mongkol
Negative pressure rooms are crucial for the prevention of the dispersion of infectious diseases. Using the ANSYS-Fluent finite volume method (FVM), standard k (Formula presented.) ϵ turbulent, species transport, and discrete phase model with the transient condition, this research aims to reduce the amount of airborne contamination inside the negative pressure room. In the current design, both 10 area ratios and static supply pressures (Formula presented.) 1–(Formula presented.) 30 Pa are considered. The optimum condition is reached at an area ratio of 9 and 13 Air change per hours (ACHs) with a 96% reduction in CO<inf>2</inf> concentration and an exhaust velocity of 3 m/s and a minimum power consumption of 247 W at a supply pressure of ((Formula presented.) 10) Pa. The effective direct airflow pattern is observed as a safe environment by analyzing the streamlines and velocity vector distributions. To prevent the infectious viruses spread, the particle tracking of coughed droplets is analyzed so that 100% of aerosol particles can be extracted within 3 s. The door-opening effect showed that the desired negative pressure could be maintained even if the door opened for a long time. This work will benefit the design engineers for any intended negative pressure room and provide a secure working environment for the medical personnel.

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