Tạp chí Khoa học Tự nhiên Đại học Quốc gia Thành phố Hồ Chí Minh

Serum samples containing hepatitis B virus (HBV) used as biological sample to examine DNA extraction capability at different nanoparticles (NPs) sizes and amounts were investigated in this study. The magnetite (Fe3O4) NPs synthesized by co-precipitation method were size about of 10 nm with the magnetic saturation of 60.02 emu/g. Using solvothermal method with different synthesis times obtained the Fe3O4 NPs sizes of about 32, 60 and 100 nm with the magnetic saturations of 88.82, 83.69 and 80.29 emu/g, respectively. The synthesized Fe3O4 NPs had superparamagnetic properties. By Stöber method, the Fe3O4 NPs were coated with SiO2 (Fe3O4@SiO2) to form Si-OH groups through which the NPs could adsorb DNA via hydrogen bonds. The properties, morphology, size and DNA adsorption capacity of the NPs were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) method, and polymerase chain reaction (PCR). The results showed that synthesized Fe3O4@SiO2 NPs could extract HBV DNA. The Fe3O4@SiO2 NPs obtained from 10 nm Fe3O4 NPs had better HBV DNA extraction. At high HBV concentration (109 copies/mL), using 3 or 4 mg of Fe3O4@SiO2 NPs (10 nm Fe3O4) could extract more HBV DNA than using 2 mg.

Section of weathering crust developed on the biotite granite (ankroet complex), distributed on high leveling surfaces 1400–1700 m of Miocene age (N1) at Trai Mat area and around Da Lat city. In terms of petrographic characteristics, this weathered shell section is full of zones: laterite, litoma, saprolite, and the original stone. On chemical-mineral characteristics: The results of synchronous processing of the results of chemical, thermal and jealous analysis ... on vertical sections shows, they belong to the form of fealsit formation (FeAlSi) with 4 types of shells: Fealsit / goethite-kaolinite-gibsit (FeAlSi / gt-kl-gb / N1), AlSiferit / (kaolinite-hydromica) -gibsit-goethit (AlSiFe / (kl-hmi) -gb-gt / N1), Sialit (actually receptors) / kaolinite-hydromica (SiAl / kl-hmi / N1) and Sialit (alkaline) / kaolinite rock-forming minerals (SiAl / kvtđ-kl / N1-Q). About microelements: concentrate in VPH compared to original stone: Cu: 1.8 – 3.3 times, Pb: 1 – 2 times, Mo: 0 – 2.83 times, most other elements were removed from the shell. Related minerals: Camp Mat, Da Lat Kaolin can be used as raw material for producing white bone tiles and birth materials. In this weathered shell section, there is a weathered shell of AlSiferite / (kaolinite-hydromica) -gibsit-goethite (AlSiFe / (kl-hmi) -gb-gt) which is a weathered clay-rich weathering product (gibsit up to 30 - 40%), developing on biotite granite at Mat camp - Da Lat area is often seen only in basalt weathering crust which is very rare in granite.  

Co2[Fe(CN)6]/Fe3O4 nanoparticle adsorbent for ion cesium (Cs+) sorption was prepared by a chemical co-precipitation method. The magnetization of the materials makes them to be separated easyly from an aqueous solution by an external magnetic field. The ion Cs+ absorption by Co2[Fe(CN)6]/Fe3O4 nanoparticle follow the ion exchange mechanism, ion exchange capacity depends on the pH, the maximum ion exchange capacity of the material at pH = 4 is 0.40 meq (Cs+)/ g. After 15 min, about 98% of initial ion Cs+ concentration was removed from the solution, the adsorption could be described by Langmuir and Freundlich isotherms. The high adsorption capacity and good performance on other aspects, make the Co2[Fe(CN)6]/Fe3O4 nanoparticle a promissing adsorbent for the removal of ion Cs+ from water.

Research was undertaken from 2013 to 2017, in eleven provinces and cities, in the Red river delta, Vietnam. Samples were collected from fives types of habitat as follow: natural forest, human – disturbed forest, grassland, cultivated land with perennial plants, agricultural land with annual plants. Samples were also taken from five types of soil: coastal saline - acid soil, acid alluvial soil, neutral alluvial soil, ferritic brownish soil derived from limestone and emaciated greyish soil. In this research, we recorded 283 oribatida species, beloning to 129 genus, 59 families. Among them, 49 species were not defined to species. In comparison with the recordes of Vu Quang Manh (2013) and Ermilov (2015), there are 108 species were for the first time recorded for research region fauna and 65 speciesare new for the Vietnamese fauna. Species diversity of oribatida community in each type of soil and in each habitat are different from each others. The species number in each soil type oscillated from 78 species to 178 species. The species number in each habitat oscillated from 95 species to 127 species. The rate of species which only were recorded in one type of soil or in one habitat is high. The results show that soil types and habitats are in close relationship with oribatida community. It is the scientific base for using oribatida community as a biodiversity for soil quality.  

We propose in this paper a spectral method for the Boltzmann equation for gases with viscosity/friction. We describe the density of particles and compare the results in the case of gases with friction and rarefied gas. This is the first numerical result for the equation. We show numerically that under the presence of the viscosity, the solution dissipates to 0. The larger the viscosity is, the faster the solution converges to 0.

This study was conducted to provide a preliminary assessment on the microbial pollution in the air at some garbage collecting places and waste transferring stations at Ho Chi Minh City. The airborne microbial pollution is becoming more and more important, so the research was carried out to build long-term practical solutions that directly or indirectly protect the environment and ensure the human health. We performed sampling at 3 locations and quantitative analysis - identification for bacteria and fungi that existed in the outdoor air at the collected places of some districts. Samples were collected from 03–06/2019 according to Koch's deposition method. Sampling plate was placed at a height of 1.5 meters above the ground, and the sampling time was 15 minutes. The dish after collecting the sample was placed in the incubator at 37 +/- 1 oC in 24–48 h for bacteria and 25 +/- 1oC in 72–120 h for fungi. The study results showed that the density of bacteria and fungi ranged between 6,408.1–14,599.9 CFU/m3 and 733.6–2.497.6 CFU/m3. In particular, the density of bacteria tended to increase from the morning to the afternoon and decreased slightly in the evening, but the density of fungi tended to increase from the morning to the evening. All strains of microorganisms in the outdoor air were influenced by human activities and environmental factors. Dominant microorganisms were identified including Bacillus pseudomycoides, Bacillus pumilus, Arthrobacter cretinolyticus, Staphylococcus kloossi, Bacillus sp. and the three common fungi including Cunninghamella sp., Aspergillus flavus and Aspergillus brasiliensis. All these microbes are associated with a number of human diseases.

Rural areas and rural livelihoods in many countries have been affected by changes in natural and environmental conditions. In areas where livelihoods relied on the floodwater, changes in flood regimes and the natural environment had significantly impacted many farmers' livelihoods. In the Mekong Delta flooded areas, flood patterns changed mainly due to the hydropower development and the climate change. The livelihoods of many farmers, primarily rice farmers, were facing challenges and needed changes to adapt to the sustainable livelihood development. This study used a sustainable livelihood framework of DFID to assess factors affecting the sustainability in agricultural livelihoods in flooded areas of An Giang province, specifically at Phu Hiep and Phu Long communes of Phu Tan district. We interviewed 60 farmers based on the structured questionnaire and conducted two focus group discussions with more than 40 participating farmers. Our results of the Livelihood Capitals Index (LCI) showed that natural and physical capitals had less impact on household livelihoods. Phu Long is less affected than Phu Hiep by assessing five capitals. Farm households' current livelihoods were mainly affected by the lack of human resources and the unstability of market prices. The rate of consensus on transition to sustainable farming models was not high due to many factors. However, the transition is possible if their production and output are secured by the government.

In the emergency that the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has globally spread, vaccine is one of the most indispensable defense lines to repulse the resulting Coronavirus Disease 2019 (COVID-19) pandemic. The effective immunization frequently requires appropriate adjuvants which play a key role to activate the dendritic cell maturation. Indeed, the antigen presentation of dendritic cells indisputably needs the collaboration of co-stimulatory molecules which are only expressed by mature dendritic cells to trigger T cell response. In this review, we collectively summarized well-known adjuvants used for vaccination as well as their characteristics and immunostimulatory effects on both of humoral and cell-mediated immune response. Besides, the applicability of adjuvants in COVID-19 vaccination and accompanying challenges were also discussed. Generally, despite of certain successes of available licensed adjuvants in the vaccination, new generations of novel adjuvants would absolutely be required to produce effective vaccines for other inevitable pathogenic organisms in the future.

In this paper, we investigate the spin state of the Fe3O cluster from MIL-100(Fe), each Fe site of which possesses either one unpaired electron, three unpaired electrons, or five unpaired electrons. Total energies with respect to different spin states were optimized with the PBE, B3LYP, HF, and MP2 methods in combination with various basis sets (6-31G, 6-31G*, 6-311G(d,p)) for non-metal ions and pseudopotentials for Fe (SDD and LanL2DZ). The results of B3LYP, MP2, and HF methods predicted that each Fe site had five unpaired electrons in the most stable spin state. However, the results of PBE show two opposite cases. In one case, PBE predicted each Fe had one unpaired electron, while in the remaining PBE cases, each Fe site was predicted to exhibit five unpaired electrons. We finally conclude the Fe3O cluster with 15 unpaired electrons is the most stable structure.

Nematode communities were used as a tool to assess the environmental quality status of sediment of the water bodies in Ben Tre city. Eight locations in the main canals and river in the city were surveyed during the rainy season (September). The study recorded 51 genera belonging to 33 families, 10 orders (Araeolaimida, Chromadorida, Desmodorida, Dorylaimida, Enoplida, Monhysterida, Mononchida, Plectida, Rhabditida, and Triplonchida), 2 classes (Chromadorea and Enoplia). The density of nematode communities at most survey locations is quite high, ranging from 29.88 +/- 38.01 to 1172.08 +/- 659.74 individuals/10 cm2. However, the biodiversity is quite low, species richness index (S) ranged from 5.33 1.15 to 18.33 4.72, and Shannon diversity index (H') from 1.28 +/- 0.12 to 3.19 +/- 0.50 and Pielou's evenness index (J') from 0.47 +/- 0.04 to 0.93 +/- 0.04. The Maturity Index (MI) of nematode communities was applied to assess the environmental quality status of sediment. The results showed that the environmental quality status of sediment recorded disturbances, classified as bad to moderate. The colonizer-persister (c-p) combined with the MI is a potential tool in biological monitoring of environmental quality status. However, to increase the reliability of evaluation conclusions, the combination of MI and biological indicators as well as physical-chemical parameters is necessary.