Silver - chitosan (Ag@CS) nanoparticles were synthesized by in-situ encapsulation method, which achieved an average size of 12.6 nm, uniform particles, well-dispersed particles in water and stable. Experimental results show that the temperature and reaction time have greatly affected on the formation of Ag@CS nanoparticles, particle size and uniformity. The optimal temperature is 60oC during 3 hours to obtain Ag@CS nanoparticles with Ag content of 9.01%. The zeta potential of Ag@CS in the colloidal form obtained after 3 months has a value of +25.6 mV, proving that Ag@CS particles have good stability, opening up the potential for using this material system as a plant protection product.

In this study, graphene nanoplatelets material was synthesized by a simple, effective, rapid method, saving chemicals and time as a “green” approach for application orientation in environmental treatment. The FTIR analysis results confirmed that the functional groups and bonds were formed on the surface of the graphene nanoplatelets. Simultaneously, the FESEM images showed that the obtained material has about 10-40 thin layers stacked on top of each other, wrinkled with folds, and rolls typically for graphene. Meanwhile, XRD diffraction spectrum analysis exhibits characteristic peaks for graphene with a strong diffraction peak of 2θ = 26.6o. Graphene nanoplatelets material is a potential precursor for environmental treatment when combined with other photocatalytic materials.

Outward investment policy has been an important part of China's reform and opening-up since 1978. However, it has really made major breakthroughs since China stepped up the implementation of its “going out” strategy in the early years of the twenty-first century. Through preferential policies and measures on tax, financial and monetary reform, aid to countries, establishment of an investment support fund, and reform of administrative procedures, China is constantly expanding its investment to foreign countries, becoming one of the world’s leading countries in this field. China's investment development strategy has had a certain impact on Vietnam - China economic relations in the period 2010-2020. It has contributed to promoting Chinese investment in Vietnam, enhancing trade cooperation between the two countries; but on the other hand, it also makes the trade balance unbalanced, causing some limitations and inadequacies in the process of Chinese investment in Vietnam.

Magnetite (Fe3O4) nanoparticles were synthesized by thermal decomposition method of iron (III) acetylacetonate (Fe(acac)3) in organic solvent, then, was performed phase transfer and coated with poly acrylic acid (PAA). The crystalline structure, morphology and magnetic properties of samples were characterized by X-ray diffraction patterns (XRD), transmission electron microscope (TEM), fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The PAA-cappped Fe3O4 nanoparticles has spinel single phase structure with average size of 10 nm and high saturation magnetization (up to 64 emu/g). The amounts of Fe3O4 magnetic particles in the samples were 84.27% weight for the sample Fe3O4@PAA. The magnetic Fe3O4 nano material was formed in liquid phase with high homogeneity, mono-dispersion, as well as good stability promised a potential application in biomedical