From samples of moldy wall paint and damaged water-based paint, we isolated and quantified the density of microorganisms present in the samples and determined the morphology of the isolates; thereby, identifying the genera of the bacteria and mold strains. The results showed that the density of the strains collected from the wall paint samples was much higher than that of the water-based paint samples (106 CFU/mL and 104 CFU/mL, respectively). In the wall paint samples, only mold colonies were observed, not bacterial colonies, while in the water-based paint samples both mold and bacterial colonies appeared, although mold colonies were still predominant. Based on the observation of colony formation and microscopic morphology of molds, we classified six mold strains into five genera: Aspergillus sp., Cladosporum sp., Acremoium sp., Chaetomium sp., and Fusarium sp. The frequency of strains belonging to the genus Aspergillus sp. accounted for the majority in both wall and water-based paint samples. Among the three bacterial strains isolated, we identified two bacterial strains as G (-) and one strain as G (+).

This paper aims to investigate the fabrication of high strength low alloy (HSLA) steels by wire and arc-based directed energy deposition (WADED). Firstly, the relationship between the process variables (including the travel speed-V, the current-C, and the voltage-U) and the geometrical characteristics of weld beads (including the bead height (BH), bead width (BW), and melting pool length (MPL)) was investigated. Secondly, the optimal process variables were identified using the desirability approach. The results indicate that voltage-U has the highest impact on BW and MPL, meanwhile the travel speed-V is the most impacting factor on BH. The optimal variables for the WADED process of HSAL steels are V = 0.3 m/min, C = 160 A, and U = 19 V. The component fabricated with the optimal variables is fully dense without spatters and defects, confirming the efficiency of the WADED process for HSLA steels.

Apatite ore from Lao Cai province (Vietnam) has large reserves and low cost which was purified by a simple chemical method. Apatite ore and purified one were characterized the molecular structure, phase component, specific surface area, element component, and morphology by IR, XRD, BET, EDX, and SEM methods. The IR result shows both materials have functional groups of fluorapatite such as PO43- and F-. XDR and EDX confirm that the main component of the ore is fluorapatite. After purification, the particles are smaller and more uniform with a higher specific surface area (36.62 m2/g compared with 3.76 m2/g of original apatite ore). Two materials were used to adsorb Pb2+ ions in an aqueous solution. The effect of adsorbent mass, pH, Pb2+ initial concentration, and contact time on adsorption efficiency and capacity was evaluated. The study of adsorption kinetics and isothermal adsorption showed that the Pb2+ adsorption process on apatite ore is matched with the pseudo-second-order kinetic model and the Langmuir model. The comparison between the original apatite ore and purified one was also studied. With 0.05 g of absorbent, after 15 minutes, the efficiency of purified ore is 97.47%, much higher compared with the original ore (50%) after 45 minutes.