Worananthakij, Worakrit
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Item type:Publication, Microwave-assisted biosynthesis of silver nanoparticles using two marine microalgal extracts and their antimycobacteriosis activity against bacteria isolated from Betta splendens(2025-12-01); ; ; This study explores the synthesis and antibacterial properties of silver nanoparticles (AgNPs) as a safer, eco-friendly alternative to traditional chemical treatments for bacterial infections. AgNPs were synthesized using aqueous extracts of marine microalgae, Isochrysis galbana and Chaetoceros calcitrans, via conventional and microwave-assisted methods, with the latter accelerating nanoparticle production. Extracts in ethanol, hexane, and acetone were tested, with the ethanolic extract of I. galbana showing the strongest antibacterial effects. The AgNPs exhibited broad-spectrum antibacterial activity against pathogens such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and fish pathogens like Aeromonas veronii. Microwave-assisted synthesis with ethanolic extracts resulted in the highest inhibition, particularly against fish and tuberculosis-related pathogens, including Mycobacterium marinum. Nanoparticle formation was confirmed using various characterization methods, including ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), which revealed crystalline structures. Transmission electron microscopy (TEM) analysis revealed that AgNPs varied in size, with an average diameter of less than 50 nm and all particles being smaller than 100 nm. This research demonstrates the potential of AgNPs as an effective alternative to antibiotics, offering targeted bacterial inhibition while reducing the risk of antibiotic resistance. This makes it a promising approach for treating bacterial infections in ornamental fish. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Ultrathin AlN barrier coatings for enhancing surface chemical stability and suppressing electrochemical migration in immersion silver–finished printed circuit boards(2026-08-15); Immersion silver-finished printed circuit boards (PCB-ImAg) provide low contact resistance and excellent solderability, but their chemical instability in humid and sulfur-containing environments can compromise long-term reliability. In this study, ultrathin aluminum nitride (AlN) films (20–60 nm) were deposited on PCB-ImAg substrates by reactive DC magnetron sputtering as inorganic barrier layers. Their protective performance was evaluated by accelerated H<inf>2</inf>S exposure, long-term ambient air exposure, tape testing, electrical resistance measurements, electrochemical migration (ECM) testing under a 3 V bias at 30 °C and 80% RH, and surface characterization. Uncoated PCB-ImAg samples showed severe tarnishing, Ag<inf>2</inf>S formation, dendritic corrosion, and a marked increase in electrical resistance after both H<inf>2</inf>S and prolonged air exposure. In contrast, AlN-coated samples retained a cleaner surface, remained adherent after the tape test, and showed much smaller resistance changes. X-ray photoelectron spectroscopy detected sulfur-related chemical states only on the uncoated surfaces, indicating suppression of sulfide formation by the AlN layer. A 20 nm AlN coating was sufficient for anti-tarnish and ambient air stability, whereas coatings of 40 nm or greater were required for robust ECM suppression. These results demonstrate that ultrathin AlN films effectively improve the corrosion resistance and ECM reliability of PCB-ImAg surfaces. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Highly transparent flexible CuI film for antibacterial applications(2022-02-01); ; ; In this study, the CuI film was firstly revealed to have significant antibacterial activity. The as-prepared CuI thin films on flexible plastic (polyvinylchloride, PVC) substrates were developed by the liquid iodination method. This method is simple, low-cost and environmentally friendly to fabricate flexible CuI films. A suitable reaction time between the Cu<inf>3</inf>N precursor and aqueous iodine solution is the key parameter for developing highly transparent CuI films, and an average transmittance in visible spectrum was higher than 85%. In addition, the CuI films have prominent antibacterial effects against Staphylococcus aureus and Escherichia coli. These properties indicate that CuI films are promising for built-in application to top layer displays in public places, such as hotel and department stores, ticket machines and touch screens in smart devices. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effects of Ag-doped Content on Antimicrobial Activity and Substrate Color of Chromium Thin Films Deposited by DC Magnetron Sputtering(2024-10-26); ; Silver ions (Ag<sup>+</sup>) show promise as excellent antimicrobial agents to inhibit microbial growth on high-touch surfaces. In this study, Ag-doped Cr films were deposited using a DC magnetron sputtering system from a mosaic target. The Cr-Ag mosaic target was a 0.125-inch-thick Cr base (99.95% pure) with different diameters of Ag circle sheets mounted on the Cr target. The sputtering condition was kept at a DC power of 100W, working pressure of 8.3x10<sup>-3</sup> mbar with Ar as the sputtering gas, and sputtering times of 15 and 30 min. The antimicrobial activity and efficiency were determined by standard testing (JIS Z 2801: 2000). The antibacterial performance was calculated from the antibacterial inhibition of the Ag-doped Cr films in bacterial solution (Staphylococcus aureus and Escherichia coli) after 24 h. The results showed that the Ag content was between 0.27 at% and 6.11 at% depending on the diameter of Ag and the deposition time. The minimum Ag content of 4.05 at% had an inhibition efficiency of 99.98% (E. coli) and 96.33% (S. aureus). The contact angle testing of Ag-doped Cr films showed hydrophobic behavior with the angle greater than 90 degrees. The optical color of the Ag-doped films was characterized by UV-vis spectroscopy (CIE testing). The film colors were significantly changed by the addition of Ag into the Cr films. The total color difference (∆E) increased by 3-10 units compared to the reference chromium film and the Ag doping mainly affected +L* (Lightness).1