Key Engineering Materials Vol. 862

Abstract: Eighty-one microbial odors were isolated and identified based on phenotypic characterization and 16S rRNA gene sequence similarity. The dominant microbial odors (Group C, 27 isolates) were classified as Staphylococcus hominis subsp. hominis DSM 20328^T. The genome annotation of all representative microbial odors revealed that they consisted of malodor biosynthesis pathways; short-chain volatile fatty acids (VFAs) and thioalcohol (3-methyl-3-sulfanyl-hexan-1-ol, 3M3SH). Among them, 3M3SH was the most important malodor compound and its key enzyme was cystathionine beta-lyase. To screen the cystathionine beta-lyase inhibitors by docking with PyRx, three bioactive compounds from natural products [gallic acid (CID 370), 1-heneicosanol (CID 85014) and 2,6-dimethylheptadecane (CID 545603)] were predicted to be effective in binding with the target enzyme close to the synthetic inhibitor [N-(2-Hydrazinyl-2-oxoethyl)-3-(trifluoromethyl)benzamide (CID 16109340)]. The water extract of Terminalia catappa L. revealed the highest inhibitory effect against the growth of all microbial odor isolates. Hence, our study concludes that the bioactive compounds of T. catappa L. may be used as an appropriate natural source to develop the natural sport deodorant spray in the future.

Abstract: Agar and banana (Gros Michel) powder composite film with silver nanoparticles were prepared using a solution casting method. Then, the ratio of agar and banana powder also the concentrations of silver nitrate solution have affected the properties of biocomposite film. These physical properties were characterized by UV-Vis spectrophotometer and colorimeter. The results indicated that biocomposite film with the mass ratio of agar to banana = 3:1 (A₃B₁_Ag50) was brown and had the maximum absorption of UV-Vis light at 432 nm. This biocomposite film exhibited strong antibacterial activity against both Escherichia coli and Staphylococcus aureus. Because of their microbial activity and physical properties, these biocomposite films have the potential to be used extending the shelf life of food packaging.

Abstract: In this research, we compare two samples of Liquid Crystal sheet (LCs), R30C5W and R35C5W to get information about the characteristic of LCs based on the color-play of the LCs surface caused by increasing of temperature. We analize the color-play of the samples quantitatively by image analysis using hue parameter, texture analysis method by choosing entropy and energy parameter, and color-play area measurement. According to the experiment results, both samples show the similar characteristic in color-play behaviour, illustrated by similar curve for each sample, the different only in the starting temperature of the color-play and the clearing point temperature. The samples also show the same behavior in increasing of the color-play area linearly by increasing of temperature. Based on the graph of hue, entropy and energy parameters, it can be measured the clearing-point temperature of samples at 43 °C and 49 °C for LCs R30C5W and LCs R35C5W respectively. Moreover, the changes of color from red to blue cause the irregularity of pattern illustrated by increasing of entropy values and decreasing of energy values. Study the characteristic of LCs in various types is important particularly before it is used for many application purposes, for instance in heat transfer observation.

Abstract: Successfully pressure-sensitive adhesives have been used by many industrial tape and label applications.This tape widely used in daily life of adhesive bandage. In this work, the novel the adhesive is fabricated from glutinous rice flour, gelatin, polyvinyl alcohol, borax, methyl paraben and glycerol. Characteristics of adhesive were then investigated by scanning electron microscopy (SEM), and swelling ratios. Mechanical characterization and tissue adhesive bonding test of the final product were also performed.

Abstract: Rice-based gel is intended to be a coupling agent for usage in ultrasonic application, which made from blending of rice starch powder, sodium hydroxide, carboxymethyl cellulose, glycerin, and water. In this study we test the products for safety and efficacy in 100 patients, by four physicians. The imaging results revealed that, when compared with standard ultrasound gel, rice gel can produce equal clearness but with better echogenicity. So, rice-based ultrasound gel should be an alternative choice for general hospitals.

Abstract: Surgical obturators are important oral prostheses given to patients after surgical treatment to minimize scar contracture and esthetic disfigurement that may affect patients’ functional appearance and psychological health. Poly-methyl methacrylate (PMMA) resin has been the material generally used for fabrication of surgical obturator. However, wearing of this resin appliance can raise a condition for microbial biofilm accumulation and infection of the patients due to the rough surfaces and internal porosities of the resin. Vanillin-incorporated heat-cured and auto-polymerized PMMA resin have been developed and demonstrated to have antimicrobial activity against several types of microorganisms. This study aimed to examine antimicrobial properties of vanillin-incorporated auto-polymerized surgical obturator resin on the biofilm formation of Streptococcus mutans and Candida glabrata. The auto-polymerized PMMA resin samples (Orthocryl® EQ, Germany) were prepared with vanillin incorporation (0.1% and 0.5% vanillin). All samples were coated with sterile saliva and incubated at 37 °C for 60 min. The suspensions of S. mutans ATCC 25715 and C. glabrata ATCC 15126 (10⁷ colony forming unit/mL) were prepared using McFarland standard No.1. Microbial biofilm formation was done in 96-well plate at 37°C for 24 h. The total vital biofilm formation was evaluated by Cell Counting Kit WST-8 (Dojindo Molecular Technologies, USA) at 450 nm. All tests were done in triplicate on three separate circumstances. One-way ANOVA and Tukey’s test were applied for the statistical analysis. A significant decrease of S. mutans biofilm mass was noticed in 0.5% vanillin incorporated resin group compared with a control, resin without vanillin. The percentage of biofilm reduction was 40.8%. No different effect was observed in 0.1% vanillin group. In the case of C. glabrata, no significant biofilm reduction was examined among all groups. In conclusion, the adding of 0.5% vanillin to surgical obturator resin could significantly inhibit biofilm formation of S. mutans, however, the effect was not demonstrated on 0.1% vanillin. C. glabrata was observed to be resistant to vanillin. Using PMMA resin incorporated with 0.5% vanillin, an obturator with antimicrobial property can be applied to prevent dental caries and other systemic diseases in patients after surgical treatment.

Abstract: In this study, crumb rubber was used to partially replaced fine aggregate in mortar mixture by 5, 10, 15 and 20 volume percentage (vol%) with untreated and NaOH-treated crumb rubber. There were three (3) different water-cement ratio used which are 0.45, 0.50 and 0.55. Thus, the total number of mixtures was 27. The mortars were tested for flowability, compressive strength, flexural strength and density. Based on the results, higher water cement ratio and percentage of crumb rubber replacement increased the flowability but lowered the density, compressive strength and flexural strength of the rubberized mortar. It was also discovered that the significant effect of water-cement ratio on the fresh and hardened properties of the rubberized mortar was due to the water content in the mixture. Meanwhile, the use of NaOH as treatment to crumb rubber improved the flowability, compressive strength and flexural strength of the rubberized mortar.