By atomic absorbance spectrophotometry, the content of heavy metals (lead, cadmium, arsenic, mercure) in freshwater fish and shelfish in the market and in 2 lakes in Hanoi from June to December 2002 was analysed. The contents are: lead 100%, arsenic 98.5%, cadmium 92.9% and mercury 88.6%, they are in the tolerable limits according to 1998 year Vietnam MOH regulation 867/BYT. The contents of various heavy metals are not similar in diverse genera of fish and shelfish. In some genera of fish, arsenic contents are higher than average from 0..68 to 0.601 mg/kg and mercury content 0.053mg/kg. Heavy metal contents in 2 lakes of Thanh Tri district and in diverse markets in Hanoi have not significant differences
Metals, Heavy ; Mercury ; Lead

Understanding the morphology of teeth is crucial in restorative dentistry in terms of restoring teeth’ anatomy, aesthetics, and function. Objectives: (1) this study describes an innovative method of teaching and learning tooth anatomy that applied shading techniques to 3D drawing the molar occlusal surfaces; (2) the study aims to survey learners’ opinions about the method’s effectiveness. Materials and methods: This study was conducted on 118 third-year dental students at the University of Medicine and Pharmacy, Hue University, from March to May 2022. The 3D occlusal surface drawing was developed and applied in teaching, and feedback was received from students. All statistical analysis was analyzed using SPSS version 26.0. Results: Instructions for 3D drawing were detailed and explained step-by-step, from forming to shading the occlusal surfaces. Subsequently, 57.3% - 90.9% of students self-assessed their proficiency in comprehending the characteristics of the occlusal anatomy. 73.3% - 95.8% of students agreed on the utility. 73.1% of students agreed to be willing to apply the 3D drawing method in learning other subjects. Conclusion: Instructions for 3D drawing were built step-by-step, from forming to shading the occlusal surfaces. After completing the course, a high percentage of students agreed on the advantages of this method. Further studies are needed to evaluate the effectiveness of the 3D drawing method in clinical practice

Aims: A suitable medium and cultivation parameters have an important role in the improvement of the production of pyocyanin pigment by Pseudomonas aeruginosa microorganism. The study aimed to optimize culture conditions and medium components for maximal pyocyanin production in a recombinant strain P. aeruginosa PS39-phzMS created in previous research. In addition, the process of extraction of pyocyanin was also investigated to select a proper applied solvent for recovering a high amount of pyocyanin as well as its quality. Methodology and results: The pyocyanin purification has based on solvent. Among six tested solvents for extracting pyocyanin out of bacterial broth, two out of six recovered a significant amount of pyocyanin, namely dichloromethane and chloroform, in which chloroform showed a higher pyocyanin yield (25.27 ± 1.02 µg/mL) than dichloromethane (20.26 ± 0.88 µg/mL). The thin-layer chromatography (TLC) of the extracted pyocyanin illustrated a similar to pure pyocyanin with Rf of 0.72 and no mark of other impurity metabolites. The UV-Vis spectra showed a similar peak at 520 nm with pure pyocyanin and the highest peak at 274 nm. Each single culture parameter was studied for the maximal production of pyocyanin. Next, a pyocyanin-producing GM medium was modified on the base of the KingA to find the relative capacity to biosynthesize high pyocyanin yield in P. aeruginosa PS39-phzMS. The results showed that pyocyanin production was the highest in optimal culture conditions, at 30 °C, pH 8, 120 h and agitation of 200 rpm. In the combination of culture condition with the GM, pyocyanin was created at the highest amount of 49.57 µg/mL. Conclusion, significance and impact of study Based on the obtained results of the study, a pyocyanin-producing procedure was optimized, which suggests a promising application to scale-up pyocyanin production by the P. aeruginosa PS39-phzMS.