Tổng hợp tài liệu Khoa Học Tự Nhiên tham khảo cho học sinh, sinh viên.
Li0.5Fe2.5-xCrxO4 spinel nanoparticles (x = 0, 0.5, 0.75, 1 and 1.25) were obtained by using a citrate sol-gel method. The samples have the cubic spinel structure at room temperature with the lattice constant a slightly decreases with increasing Cr content. The good crystallinity single domain particles has average diameter 22-30 nm. The core...
6 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 482 | Lượt tải: 0
Moreover, the catalytic activity does not only vary with the reaction temperatures but also depends on the oxidant nature. In practice, Figure 5A presents the different catalytic activity as different oxidants are introduced into the styrene reactant. It is worthily noted that three examined oxidants all express the good ability to oxidize st...
5 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 497 | Lượt tải: 0
To a cooled (0 oC) solution of 14a (50 mg, 0.102 mmol) in 2 mL MeOH/H2O (2:1) was added LiOH (25 mg, 1.02 mmol). The cooling bath was removed, and the resulting mixture was stirred at room temperature for 10 h. The solvent was removed in vacuum and the residue was dissolved in a small amount of H2O. The aqueous solution was cooled to 0 oC, a...
5 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 481 | Lượt tải: 0
There are eight existent feasible isomers on the potential energy surface [H, N, C, O], in which isocyanic acid and cyanic acid are the most stable isomers. The HNOC isomer contains a N O unstable donor – acceptor bond is intermediate complex forming CO, NH products. Isomerizations are difficult to occur at normal temperature and pressure co...
6 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 457 | Lượt tải: 0
In this study, the Fe2O3/SiO2 composite has been successfully prepared via a simple impregnation method. The Fe2O3 with small particle size was highly dispersed on silica and exhibited excellent efficiency for the Fenton degradation of tartrazine, 98.5 % in 80 min. It was much higher than that of physic mixture Fe2O3/SiO2, and other materials...
8 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 550 | Lượt tải: 0
The effects of combustion temperature on the tar formation and the syngas composition using oxygenenriched air were studied experimentally in a pilot scale two-stage biomass gasification system with different oxygen-enriched air. In this study, the oxygen level in the gasifying agent was increased from 21 to 42 vol.%. The experiments of severa...
6 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 554 | Lượt tải: 0
DFT calculations find that the equilibrium structures of the Ag-NHE show major differences in the bonded orientation of NHPb ligand in Ag-NHPb compared with NHE ligands the slighter homologues Ag-NHE (E= C-Sn). The BDE results show that the Ag-carbene bond in Ag-NHC is very strong bond and decreases from the slighter to the heavier homologue...
8 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 629 | Lượt tải: 0
The most difficult assignment was identification of C13/C19 and H13/H9. Fortunately, it was easily to find H14 that had an HMBC cross-peak with H9. Therefore, H13 and C13 were identified and so on. Other assignments were shown in the figure 2. Finally, compounds 3, 4, 5 and 6 were recorded for mass spectroscopy. MS spectrum of compound 3 ind...
5 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 666 | Lượt tải: 0
Seawater desalination using membrane distillation (MD) can be a pragmatic solution to fresh water scarcity in Vietnam. As a hybrid desalination process, MD inherits attributes of both pressure-driven membrane separation and thermal distillation. These attributes include process modularization, low susceptibility to feed osmotic pressure, low ris...
24 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 607 | Lượt tải: 0
In this work, the influence of climate and weather factors and natural exposure time at Dong Hoi (Quang Binh) on UV-Vis spectra, the change of color, and electric properties of HDPE/m-CaCO3 composites were investigated. The UV-Vis spectra showed the formation of carbonyl groups and vinyl groups in HDPE macromolecules of the composites by the...
7 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 476 | Lượt tải: 0
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