排序方式: 共有54条查询结果,搜索用时 15 毫秒
31.
Chu Jin Kiat Lim Mitchell S. W. Tiong T. Joyce Yap Yeow Hong Lim Li Yan Yeoh Pricella S. J. Kumar Kavin Chong Siewhui Chan Yi Jing Pan Guan-Ting Yang Thomas C. K. 《Research on Chemical Intermediates》2019,45(12):6003-6019
Research on Chemical Intermediates - This paper studies the effect of addition of Zn and ultrasound-assisted co-precipitation on Cu-Mn oxide catalysts for the oxidation of CO. Cu-Mn-Zn oxide... 相似文献
32.
Klaus‐Dieter Liss Ross E. Whitfield Wei Xu Thomas Buslaps LaReine A. Yeoh Xiaolin Wu Deliang Zhang Kenong Xia 《Journal of synchrotron radiation》2009,16(6):825-834
Mixtures of 47‐Al and 53‐Ti powders (atomic %) have been consolidated using back pressure equal‐channel angular pressing starting with both raw and ball‐milled powders. In situ synchrotron high‐energy X‐ray diffraction studies are presented with continuous Rietveld analysis obtained upon a heating ramp from 300 K to 1075 K performed after the consolidation process. Initial phase distributions contain all intermetallic compounds of this system except Al, with distribution maxima in the outer regions of the concentrations (α‐Ti, TiAl3). Upon annealing, the phase evolution and lattice parameter changes owing to chemical segregation, which is in favour for the more equilibrated phases such as γ‐TiAl, α2‐Ti3Al and TiAl2, were followed unprecedentedly in detail. An initial δ‐TiH2 content with a phase transition at about 625 K upon heating created an intermediate β‐Ti phase which played an important role in the reaction chain and gradually transformed into the final products. 相似文献
33.
Jing Liang Wenhao Yang Anthony Chun Yin Yuen Hu Long Shuilai Qiu Ivan Miguel De Cachinho Cordeiro Wei Wang Timothy Bo Yuan Chen Yuan Hu Guan Heng Yeoh 《Molecules (Basel, Switzerland)》2021,26(21)
Biomass-derived carbon has been recognised as a green, economic and promising flame retardant (FR) for polymer matrix. In this paper, it is considered that the two-dimensional (2D) structure of carbonised peanut shells (PS) can lead to a physical barrier effect on polymers. The carbonised sample was prepared by the three facile methods, and firstly adopted as flame retardants for epoxy resin. The results of thermal gravimetric analysis (TGA) and cone calorimeter tests indicate that the carbon combined with nano Cobalt provides the most outstanding thermal stability in the current study. With 3 wt.% addition of the FR, both peak heat release rate (pHRR) and peak smoke production rate (PSPR) decrease by 37.9% and 33.3%, correspondingly. The flame retardancy mechanisms of the FR are further explored by XPS and TG-FTIR. The effectiveness of carbonised PS can be mainly attributed to the physical barrier effect derived by PS’s 2D structure and the catalysis effect from Cobalt, which contribute to form a dense char layer. 相似文献
34.
Yee Win Tan Sim Siong Leong JitKang Lim Wei Ming Yeoh Pey Yi Toh 《Electrophoresis》2022,43(21-22):2234-2249
Low-gradient magnetic separation (LGMS) of magnetic nanoparticles (MNPs) has been proven as one of the techniques with great potential for biomedical and environmental applications. Recently, the underlying principle of particle capture by LGMS, through a process known as magnetophoresis, under the influence of hydrodynamic effect has been widely studied and illustrated. Even though the hydrodynamic effect is very substantial for batch processes, its impact on LGMS operated at continuous flow (CF) condition remained largely unknown. Hence, in this study, the dynamical behaviour of LGMS process operated under CF was being studied. First, the LGMS experiments using poly(sodium 4-styrenesulfonate)-functionalized-MNP as modelled particle system were performed through batchwise (BW) and CF modes at different operating conditions. Here BW operation was used as a comparative study to elucidate the transport mechanism of MNP under the similar environment of CF-LGMS process, and it was found out that the convection induced by magnetophoresis (timescale effective is ∼1200 s) is only significant at far-from-magnet region. Hence, it can be deduced that forced convection is more dominant on influencing the transport behaviour of CF-LGMS (with resident time ≤240 s). Moreover, we found that the separation efficiency of CF-LGMS process can be boosted by the higher number of magnets, the higher MNP concentration and the lower flowrate of MNP solution. To better illustrate the underlying dynamical behaviour of LGMS process, a mathematical model was developed to predict its kinetic profile and separation efficiency (with average error of ∼2.6% compared to the experimental results). 相似文献
35.
Defect structures of BaTiO(3) and the like co-doped with variable-valence acceptors and donors are not clear particularly in transition from acceptor domination to donor domination with increasing oxygen activity. We have, thus, examined the electrical conductivity and thermoelectric power of BaTiO(3) co-doped with a variable-valence acceptor Mn(Mn(Ti)', Mn(Ti)') and a fixed-valence donor Y(Y(ba)·) in different co-doping ratios (m(d)/m(a)) as functions of oxygen activity in the range of -20 < log?a(O(2))≤ 0 at elevated temperatures of 900-1100 °C. Their systematic variations with m(d)/m(a) and log?a(O(2)) are reported, and thereby defect structures of the co-doped BaTiO(3) depending on m(d)/m(a) are determined. It is found that for the co-doping ratio 1 < m(d)/m(a) < 2, the Fermi level is pinned at a few kT's around the deep level of Mn(Ti)' across the otherwise p-type semiconducting log?a(O(2))-region of Mn-singly doped BaTiO(3), and attributed to deep acceptor-shallow donor mutual compensation 2[Mn(Ti)'] + [Mn(Ti)'] ≈ [Y(ba)·], thus turning otherwise p-type semiconducting BaTiO(3) semi-insulating. 相似文献
36.
The present work aims at utilizing compressed natural gas (CNG) as carbon source for the synthesis of carbon nanotubes (CNTs) over CoOMoO/Al2O3 catalyst via catalytic chemical vapor deposition (CCVD) method. The as-produced carbonaceous product was characterized by thermal gravimetric analyzer (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The experimental finding shows that CNTs were successfully produced from CNG while carbon nanofibers (CNFs) were formed as the side products. In addition, the catalytic activity and lifetime were found sustained and prolonged, as compared with using high purity methane as carbon source. The present study suggests an alternative route which can effectively produce CNTs and CNFs using low cost CNG. 相似文献
37.
The dispersion of bubbles into a down-liquid flow in a vertical pipe is investigated. At low flow rates, the intended design of a swarm of discrete bubbles is achieved. At high flow rates, a ventilated cavity is nonetheless formed, which is attached close to the gas sparger. Behind this ventilated cavity, three different flow regimes characterize the complex bubbly flow field downstream of the down-liquid flow: vortex region with high void fraction, transitional region and pipe flow region. In this study, a numerical model that solved the entire development of the gas–liquid flow including the extended single-phase liquid region upstream to the wall-jet and recirculating-vortex zones in order to allow a more realistic determination of the boundary conditions of the down-liquid flow was adopted. Coupling with the Eulerian–Eulerian two-fluid model to solve the respective gas and liquid phases, a population balance model was also applied to predict the bubble size distribution in the wake right below the cavity base as well as further downstream in the transitional and fully-developed pipe flow regions. The numerical model was evaluated by comparing the numerical results against the data derived from theoretical, numerical and experimental approaches. Prediction of the Sauter mean bubble diameter distributions by the population balance approach at different axial locations confirmed the dominance of breakage due to the high turbulent intensity below the ventilated cavity which led to the generation of small gas bubbles at high void fraction. Further downstream, the coalescence effect dominated leading to merging of the small bubbles to form bigger bubbles. 相似文献
38.
Zhu ShengJiang Wang JianGuo Gu Long Hamilton J. H. Ramayya A. V. Luo YiXiao Rasmussen J. O. Hwang J. K. Ding HuaiBo Li Ke Liu ShaoHua Yeoh E. Y. Xu Qiang Xiao ZhiGang 《中国科学:物理学 力学 天文学(英文版)》2011,54(1):44-48
The high spin states of neutron-rich 103Nb, 107Tc and 109Tc nuclei in A~110 region have been investigated by measuring prompt γ-γ-γ coincident measurements populated with the spontaneous fission of 252Cf with the Gammasphere detector array. In 103Nb, one-phonon K = 9/2 and two-phonon K = 13/2 γ-vibrational bands have been identified. In 107Tc and 109Tc, one-phonon K = 11/2 and two-phonon K = 15/2 γ-vibrational bands, in which the zero-phonon bands are based on K=7/2 excited states, have also been identified. The two-phonon bands are first observed in odd-Z nuclei. The characteristics for these band structures have been discussed. 相似文献
39.
Schief WK; Rogers C; Murugesh S 《The Quarterly Journal of Mechanics and Applied Mathematics》2007,60(1):49-64
Evolution of foliations of the plane is shown, under a conditionof constant divergence, to be linked to the scattering problemfor the integrable modified Kortewegde Vries hierarchy.This result is applied to a set of kinematic relations whicharise in the theory of ideal fibre-reinforced fluids. In particular,it is established that the fibres, which are convected withthe fluid, constitute generalized tractrices. 相似文献
40.
Y. Shi N. Hari Babu K. Iida W.K. Yeoh A.R. Dennis S.K. Pathak D.A. Cardwell 《Physica C: Superconductivity and its Applications》2010,470(17-18):685-688
Large, single grains of Y–Ba–Cu–O (YBCO) have been batch-processed to date by the top seeded melt growth (TSMG) process using NdBCO or SmBCO seed crystals. It has proved difficult, however, to economically batch-process light rare earth (LRE) LRE–Ba–Cu–O bulk high temperature superconductors, which have higher critical current densities and irreversibility fields than YBCO, and therefore greater potential for high field engineering applications. In this paper, we report a novel batch-process based on a cheap, readily available generic seed crystal, developed recently at Cambridge, and a TSMG melt processing technique based on cold seeding in air for the batch fabrication of Gd–Ba–Cu–O–Ag single grains. The superconducting properties of the (LRE)BCO single grains fabricated by this process are, in all respects, equivalent to those processed more conventionally in a reduced oxygen atmosphere. 相似文献