In this study, nanoparticles based on poly(lactic acid) (PLA), chitosan (CS), and nifedipine (NIF) were prepared by an emulsion method with poly(ethylene oxide) (PEO) as an emulsifier. We investigated the most suitable conditions for preparing the poly(lactic acid)/chitosan/nifedipine nanoparticles (PCNs) by changing the distilled water volume, PEO content, and PLA/CS ratio. NIFs with different contents were loaded into poly(lactic acid)/chitosan nanoparticles (PCs) to study in vitro drug-delivery systems. The PCNs were characterized with a Zetasizer particle size analyzer, field emission scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) methods. From the obtained results of the particle size parameters of the PCNs, the most suitable conditions for the preparation of the PCNs were found. The FTIR spectroscopy and XRD results show that NIF was loaded into the PCs. The PCNs had major basic particle sizes in the range 20-40 nm. NIF release from the PCNs was studied as a function of the pH of the immersed solution, the immersion time, and the NIF content. The kinetics of drug release were investigated and are reported to determine the type of release mechanism.

Phosphogypsum is a by-product of the wet phosphoric acid production. In this study, chemical compositions of phosphogypsum waste (PG) in Hai Phong diammonium phosphate plant (DAP1) and Lao Cai diammonium phosphate plant (DAP2) in Vietnam were surveyed for the purpose of gypsum recovery by P2O5, F removal to meet TCVN11833 for use treated gypsum as cement retarder. Studies of impurities P2O5, F, TOC removal by sulfuric acid 10 % at 28 0C was presented. The results found that the combination of a low concentration of sulfuric acid treatment, washing, lime neutralizing, and thermal treatment was successful in Phoshogypsum treatment for use as cement retarder. The cement test proved that treated PG could partially replace natural gypsum as a retarder.Keywords:  phosphogypsum treatment, phosphorus pentoxide removal, calcium sulfate transition phase, cement retarder.

Elsholtzia winitiana var. dongvanensis Phuong is a plant contains an essential oil characterized by an important chemical transformation. Essential oils were isolated from Elsholtzia winitiana var. dongvanensis Phuong flowers and aerial parts by hydrodistillation and analyzed for chemical constituents by GC-MS. Twenty-two components accounting for 99.99% of the total oil of flowers and twenty-three components accounting for 98.72 % of the total oil of aerial parts were identified. The composition of the essential oil contains aldehyde, aromatic ketone, monoterpenoid and secquiterpenoid. Major components found in two essential oil samples were andehyde, terpenoid, ketone benzaldehyde, germacrene D, E-caryphyllene and caryophyllene oxide. Moreover, essential oil sample isolated from flowers and aerial parts of E. winitiana var. dongvannensis was dominated by the high content of rosefuran (75.67%) and rosefuran epoxide (71.33%), respectively.

Baeckea frutescens is a tropical plant with great medicinal potential. The oil of B. frutescens has high inhibitory, antibacterial and antifungal properties, especially against Staphylococcus aureus strains. The oil of B. frutescens has a spicy, bitter and warm properties that can cure aches and pains. In this study, the essential oils were obtained by hydrodistillation and the chemical analysis of B. frutescens essential oils was carried out using GC-MS. It was revealed that main components of leaf oil B. frutescens included 26 compounds such as tasmanone (21.46%), β-pinene (15.64%), 1,8-cineole (11.32%), α-thujene (8.74%), α-pinene (7.18%), linalool (7.44%), terpinen-4-ol (5.11%), α-terpineol (4.46%), γ-terpinene (3.37%), o-cymene (2.72%). The results open new directions in the application of compounds in B. frutescens essential oils to expand research and development of pharmaceutical, cosmetic and food industries.

This study reports creating CaCO3 nanoparticle (NPs) and microparticles (MPs) from treated phosphogypsum of Dinh Vu Diamon phosphate plant in Vietnam. In this research, CaCO3 NPs and MPs were received in the system of Ca(OH)2 ‐ CO2 gas ‐ H2O by aeration method. The research samples are characterized by ultraviolet visible spectrophotometry (UV‐vis), scanning electron microscopy (SEM), X‐ray diffraction (XRD) and dynamic light scattering (DLS). The study investigated the conditions for obtaining calcium carbonate NPs and MPs when changing the aeration speed of CO2 from 40 to 120 ml/min, the concentration of Ca(OH)2 from 0.04 M to 0.5 M, the temperature from 28 to 60 oC. This research showed that the clear influence of Ca(OH)2 concentration and reaction temperature on the CaCO3 particle size in the CO2‐Ca(OH)2 system. CaCO3 morphological structure has the form of calcite with rhombohedral block (rhomboid cylindrical box).