692 research outputs found
Data assimilation in air pollution modelling
No full textElectrical Engineering, Mathematics and Computer Scienc
Magnetoelastic Coupling in Mn-Fe-P-Si Compounds
No full textMn-Fe-P-Si compounds are, to date, the most promising materials for refrigeration and energy conversion applications due to the combination of giant magnetocaloric effect (GMCE) and low material cost. The nature of magneto-elastic transition was studied on both length- and time-scales using neutron diffraction, muSR and Mӧssbauer spectroscopy techniques for Mn-Fe-P-Si compounds. The revealed strong spin-lattice coupling is responsible for the different magnetic orders, the tunability of the phase transition, and the excellent magnetocaloric properties in these compounds. This thesis contributes to a better understanding of the spin-lattice coupling and phase-transition behavior for Mn-Fe-P-Si compounds
Growth and Characterisation of Boron Rich Nanomaterials
No full textIn this study nanomaterials are grown in a solid state reaction at 1300C of boron, barium oxide and iron(II/III)oxide powders in an argon atmosphere. The nanomaterials are shown to be grown via vapour based method by growing the nanomaterials on a separate silicon wafer that has been sputtered with iron and placed downstream of the powders in the flow of argon. An area of the silicon wafer is kept free of iron by using a mask when sputtering the wafer. When nanomaterials are grown, the masked area remains free of nanomaterials. This shows that the presence of iron is vital for the nucleation of the nanomaterials and also indicates the possibility of growing these nanomaterials on targeted sites.
The nanomaterials produced are examined and it is found that we have a presence of amorphous, crystalline and multiple twinned nanowires. The evidence collected suggests that 70% of the nanowires are twinned. The single crystal nanowires can be identified as boron carbide by comparing to diffraction pattern simulations of a boron carbide unit cell. The twinned diffraction pattern is shown to be due to different segments of the nanowire being in different diffraction condition by using Dark Field imaging. The Twinned wires are also shown to have at least four segments in a cyclic [001] twinning orientation in simultaneous diffraction condition by comparing to a twinned structure constructed from simulations. Elemental analysis using Electron Energy Loss Spectroscopy and Energy Dispersive X-ray shows that the composition of the nanomaterials is mainly boron and carbon.
The role of the iron layer on the wafer is investigated to see how varying the thickness will affect the nanomaterials grown. It is successfully shown that an increase in the thickness of the iron layer results in a greater density of nanomaterials. However there is no great variation in the average diameter of the nanomaterials produced.
The absence of a visible signal for iron in the Elemental analysis of nanostructure covered silicon wafer shows that the amount of iron in the sample has decreased during the reaction. However iron is found in small amounts in droplet structures at the tips of nanomaterials this is different to work done on a similar system at 1100C. This suggests that the role of the iron in the growth of these nanomaterials at this temperature is not yet understood. However this work has confirmed that the iron is essential for the nucleation of the nanomaterials, but post nucleation growth that was previously assumed to be a conventional VLS growth may switch to an oxide assisted growth mode
SCI citation analysis and impact factor prediction of JZUS-B in 2008
No full textWe analysis the SCI citation of Journal of Zhejiang University-SCIENCE B, predict its 2008 Impact Factor in the range of 0.737~0.915, and list the top-10 SCI cited articles
A generalized kinetic model for electro-assisted catalytic wet air oxidation of triclosan on Ni@NiO/graphite electrode
No full textElectro-assisted catalytic wet air oxidation (ECWAO) is an efficient technique for wastewater treatment under ambient condition. In this work, the mineralization kinetics of triclosan (TCS) in an ECWAO process with Ni@NiO/graphite-felt (GF) electrode is studied. The TCS mineralization follows a pseudo-first order kinetics in the ECWAO process. A general kinetic model, based on the depletion of total organic carbon (TOC) as a lumped parameter, is developed. Such a kinetic model suggests the optimized ECWAO operating conditions of initial concentration of TOC at 40 mg L−1, applied current at 25 mA, and temperature at 308 K. In addition, the ECWAO is also effective for the treatment of biosphenol A (BPA) and sulfamethoxazole (SMX). Under the optimal conditions, TCS, BPA and SMX are mineralized by 92.9 ± 1.5, 90.8 ± 1.7 and 90.6 ± 1.0% within 120 min, with specific energy consumptions (SECs) of 2.2 ± 0.3, 1.4 ± 0.5, and 2.8 ± 0.6 kW h kg-TOC−1, respectively.Min Sun, Xiao-Hui Hong, Xiong-Fei Tao, Lin-Feng Zhai, Shaobin Wan
Quantum measurement via Born-Oppenheimer adiabatic dynamics
No full textThe need for experimental studies using various coupling systems for the permission of Born-Oppenheimer (BO) approximations was analyzed. The concrete problems of small spin-large spin interacting systems and microcavity-mirror of coupling dynamics were discussed. The effects were studied under the influence of adiabatic scattering. The use of BO approximation to achieve quantum decoherence for the measurement of cavity field was also suggested.EI01012111-0121116
Effect of ultrasound on the structural and physiochemical properties of organosolv soluble hemicelluloses from wheat straw
No full textMonitoring the daily variation of Sun-Earth magnetic fields using galactic cosmic rays
No full textInternational audienceThe interplanetary magnetic field (IMF) between the Sun and Earth is an extension of the solar magnetic field carried by the solar wind into interplanetary space. Monitoring variations in the IMF upstream of the Earth would provide very important information for the prediction of space weather effects, such as effects of solar storms and the solar wind, on human activity. In this study, the IMF between the Sun and Earth was measured daily for the first time using a cosmic-ray observatory. Cosmic rays mainly consist of charged particles that are deflected as they pass through a magnetic field.Therefore, the cosmic-ray Sun shadow, caused by high-energy charged cosmic rays blocked by the Sun and deflected by the magnetic field, can be used to explore the transverse IMF between the Sun and Earth. By employing the powerful kilometer-square array at the Large High Altitude Air Shower Observatory, the cosmic-ray Sun shadows were observed daily with high significance for the first time. The displacement of the Sun shadow measured in 2021 correlates well with the transverse IMF component measured in situ by spacecraft near the Earth, with a time lag of 3:31 0:12 days. The displacement of the Sun shadow was also simulated using Parker's classic IMF model, yielding a time lag of 2:06 0:04 days. This deviation may provide valuable insights into the magnetic field structure, which can improve space weather research
- …
