ATMOSPHERIC PARTICLES IN HANOI-CONCENTRATIONS OF WATER-SOLUBLE INORGANIC IONS AND SOURCE REGIONS

Joint Research on Environmental Science and Technology for the Eart

Fabrication and Magnetic Properties of Sintered SrFe12_{12}O19_{19}-NiFe2_{2}O4_{4} Nanocomposites

Two series of SrFe$_{12}$O$_{19}$/NiFe$_{2}$O$_{4}$ nanocomposite ferrites sintered in air at 850\rc{}C and 950\rc{}C were prepared using SrFe$_{12}$O$_{19}$ and NiFe$_{2}$O$_{4}$ nanopowders obtained via sol-gel method. The phase composition, surface morphology and magnetic properties of the composites were investigated using XRD, SEM and VSM respectively. For the SrFe$_{12}$O$_{19}$/NiFe$_{2}$O$_{4}$ ferrites with volume ratio ranging from 61 to 21 and sintered in 850$\r{}$C for 5 hours in air, all the specimens are composed of two phases but exhibit a typical single-phase magnetic behavior, indicating the existence of exchange coupling (EC) between the magnetically hard and soft phases. The value of coercivity H$_{c}$ decreases from 6.19 kOe to 0.574 kOe when volume of SrFe$_{12}$O$_{19}$ decreases from 6 to 1. While the samples with a mass ratio of $R_{m}$= SrFe$_{12}$O$_{19}$/ NiFe$_{2}$O$_{4}$ varying from 31 to 13 sintered in 950\rc{}C for 5 hours characterized with a ``bee waist'' type hysteresis loop. These results reveal that the magnetically hard and soft magnetic phases are not exchange- coupled. The saturation magnetization ($M_{S}$) increases from 36 emu/g to 43.3 emu/g when $R_{m}$ decreases from 31 to 13 and then decreases with $R_{m}= 12$ and 13

Entanglement of a Scattered Single Photon and an Exciton

A single photon which is initially uncorrelated with an exciton will evolve to be entangled with the exciton on their continuous kinetic variables in the process of resonant scattering. We find the relations between the entanglement and their physical control parameters, which indicates that high entanglement can be reached by changing specific parameters of exciton

Biocompatible chitosan-functionalized upconverting nanocomposites

Simultaneous integration of photon emission and biocompatibility into nanoparticles is an interesting strategy to develop applications of advanced optical materials. In this work, we present the synthesis of biocompatible optical nanocomposites from the combination of near-infrared luminescent lanthanide nanoparticles and water-soluble chitosan. NaYF4:Yb,Er upconverting nanocrystal guests and water-soluble chitosan hosts are prepared and integrated together into biofunctional optical composites. The control of aqueous dissolution, gelation, assembly, and drying of NaYF4:Yb,Er nanocolloids and chitosan liquids allowed us to design novel optical structures of spongelike aerogels and beadlike microspheres. Well-defined shape and near-infrared response lead upconverting nanocrystals to serve as photon converters to couple with plasmonic gold (Au) nanoparticles. Biocompatible chitosan-stabilized Au/NaYF4:Yb,Er nanocomposites are prepared to show their potential use in biomedicine as we find them exhibiting a half-maximal effective concentration (EC50) of 0.58 mg mL–1 for chitosan-stabilized Au/NaYF4:Yb,Er nanorods versus 0.24 mg mL–1 for chitosan-stabilized NaYF4:Yb,Er after 24 h. As a result of their low cytotoxicity and upconverting response, these novel materials hold promise to be interesting for biomedicine, analytical sensing, and other applications

ĐẶC ĐIỂM TƯỚNG ĐÁ - CỔ ĐỊA LÝ PLEISTOCEN MUỘN-HOLOCEN KHU VỰC CỬA SÔNG BA LẠT

Lithofacies and paleogeographical characteristics of late Pleistocene-Holocene deposits are related to three sedimentary system tracts: Lowstand systems tract (LST) corresponds to the low regressive phase from 50 ka BP to 18 ka BP. The sedimentary accumulative space is situated from the boundary of weathering crust to the 100 m water depth. In Ba Lat rivermouth area, the lowstand systems tract is dominated by the alluvial silty sand facies group (arLST); Transgressive systems tract (TST) in Ba Lat rivermouth area constitutes a lithofacies section including three facies in upward direction as follows: (1) Transgressive alluvial silty - sand facies (atTST). (2) Transgressive estuary sandy - mud facies (amtTST). (3) Lagoonal maximum transgressive greenish clay facies (mtTST); Highstand systems tract (HST) in the downstream Red river delta area constitutes a deltaic plain structure consisting of three parts: High subaerial delta, low subaerial delta and subaqueous delta, which had been formed from 5 ka BP.Đặc điểm tuớng đá - cổ địa lý trầm tích Pleistocen muộn-Holocen khu vực cửa sông Ba Lạt gắn liền với ba miền hệ thống trầm tích: Miền hệ thống trầm tích biển thấp (LST) tương ứng với pha biển thoái thấp từ 50.000 năm BP đến 18.000 năm cách ngày nay. Không gian tích tụ của miền hệ thống này được giới hạn từ ranh giới miền xâm thực (vỏ phong hóa) đến độ sâu 100 m nước. Trong khu vực cửa Ba Lạt nhóm tướng aluvi biển thoái thống trị (arLST); Miền hệ thống trầm tích biển tiến (TST) trong khu vực cửa sông Ba Lạt cấu thành một mặt cắt gồm ba tướng từ dưới lên: (1) tướng cát bột aluvi biển tiến (atTST), (2) tướng bùn cát cửa sông biển tiến (amtTST) và (3) tướng sét xám xanh vũng vịnh biển tiến cực đại (mtTST); Miền hệ thống trầm tích biển cao (HST) trong khu vực hạ lưu châu thổ sông Hồng tạo nên một cấu trúc đồng bằng châu thổ bao gồm: Đồng bằng châu thổ cao, Đồng bằng châu thổ thấp và châu thổ ngập nước có tuổi từ 5.000 năm BP

INVESTIGATION OF ARSENIC RELEASE FROM SEDIMENT MINERALS TO WATER PHASES -MOTIVATION FOR ARSENIC MITIGATION TECHNOLOGY

Joint Research on Environmental Science and Technology for the Eart

Investigating the leaching performance of ferric chloride solution for metallic alloys resulting from reduction smelting of spent lithium-ion batteries

Smelting reduction of spent lithium-ion batteries (LIBs) produces metallic alloys containing Co, Ni, Cu, Mn, and Fe. Finding suitable reagents in terms of efficiency, economics, and friendly environment for the dissolution of these metals from the alloys is very important for the recovery process of the metals. In this work, the employment of ferric chloride solution for the dissolution of the metals from the alloys was studied. The effect of parameters like FeCl3 concentration, temperature, time, and pulp density on the leaching efficiency of metals was investigated. Our results indicate that ferric ions in the leaching solutions act as oxidizing agents for the dissolution of the metals, while chloride anions as ligands for the formation of the complexes of the dissolved metal ions. The best conditions for the dissolution of full metals were 0.7 mol/L FeCl3, 12.5 g/L pulp density, 22oC, and 30 min. In comparison with HCl or H2SO4 leaching agents, ferric chloride shows some advantages like a decrease in the dosage of acids and oxidizing agents, fast reaction kinetics, and low energy consumption. With its advantages, ferric chloride solution is considered a potential leaching agent in the recovery process of valuable metals from spent LIBs

How Digital Natives Learn and Thrive in the Digital Age: Evidence from an Emerging Economy

As a generation of ‘digital natives,’ secondary students who were born from 2002 to 2010 have various approaches to acquiring digital knowledge. Digital literacy and resilience are crucial for them to navigate the digital world as much as the real world; however, these remain under-researched subjects, especially in developing countries. In Vietnam, the education system has put considerable effort into teaching students these skills to promote quality education as part of the United Nations-defined Sustainable Development Goal 4 (SDG4). This issue has proven especially salient amid the COVID−19 pandemic lockdowns, which had obliged most schools to switch to online forms of teaching. This study, which utilizes a dataset of 1061 Vietnamese students taken from the United Nations Educational, Scientific, and Cultural Organization (UNESCO)’s “Digital Kids Asia Pacific (DKAP)” project, employs Bayesian statistics to explore the relationship between the students’ background and their digital abilities. Results show that economic status and parents’ level of education are positively correlated with digital literacy. Students from urban schools have only a slightly higher level of digital literacy than their rural counterparts, suggesting that school location may not be a defining explanatory element in the variation of digital literacy and resilience among Vietnamese students. Students’ digital literacy and, especially resilience, also have associations with their gender. Moreover, as students are digitally literate, they are more likely to be digitally resilient. Following SDG4, i.e., Quality Education, it is advisable for schools, and especially parents, to seriously invest in creating a safe, educational environment to enhance digital literacy among students