Influence of growth ambience and doping on the structural properties of multiferroic DyMnO3

We report on the single crystal growth of 50% Sr and Y doped multiferroic DyMnO3 using optical floating zone technique. A comparison of the effect of growth ambience and of chemical substitution on the crystal structure of DyMnO3 is attempted. It is observed that DyMnO3 adopts Pm3m cubic structure with 50% Sr doping whereas with 50% Y doping, the crystal structure is hexagonal P6(3)cm. Orthorhombic Pnma structure is adopted by DyMnO3 when grown in air, whereas hexagonal P6(3)cm structure is obtained when grown under the ambience of argon. The structural polymorphism is discussed in terms of difference in ionic sizes of Sr, Y and Dy, comparable Gibbs free energies and coordination schemes of surrounding oxygens for hexagonal and orthorhombic structures of DyMnO3. (C) 2012 Elsevier B.V. All rights reserved.

Hetero-tri-spin 2p-3d-4f] Chain Compounds Based on Nitronyl Nitroxide Lanthanide Metallo-Ligands: Synthesis, Structure, and Magnetic Properties

Employing nitronyl nitroxide lanthanide(III) complexes as metallo-ligands allowed the efficient and highly selective preparation of three series of unprecedented heterotri-spin (Cu Ln-radical) one-dimensional compounds. These 2p-3d-4f spin systems, namely Ln(3)Cu(hfac)II(NitPhOAII)41 (Ln(III)=Gd 1(Gd), Tb 1(Tb), Dy 1(Dy); NitPhOAII=2-(4'-allyloxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3- oxide), Ln(3)Cu(hfac)II(NitPhOPO4] (1-nrn=Gd 2Gd, Tb 2Tb, Dy 2(Dy), Ho 2HOf Yb 2yb; NitPhOPr= 2-(4'-propoxyphenyI)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) and Ln3Cu(hfac)II(NitPhOB441 (LnIm=Gd 3Gd, Tb 3Tb, Dy 3(Dy); NitPhOBz=2-(4'-benzyloxy- phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) involve O-bound nitronyl nitroxide radicals as bridging ligands in chain structures with a Cu-Nit-Ln-Nit-Ln-Nit-Ln-Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal radical interactions take place in these heterotri-spin chain complexes, these and the next-neighbor interactions have been quantified for the Gd derivatives. Complexes 1Tb and 2Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single-chain magnet behavior.

Orientation Selection and Microstructural Evolution in Directionally Solidified Tb0.3Dy0.7Fe1.95

Tb0.3Dy0.7Fe1.95 alloy was directionally solidified by using a modified Bridgman technique at a wide range of growth rates of 5 to 100 cm/h. The directionally grown samples exhibited plane front solidification morphology up to a growth rate of 90 cm/h. Typical island banding feature was observed closer to the chilled end, which eventually gave rise to irregular peritectic coupled growth (PCG). The PCG gained prominence with an increase in the growth rate. The texture study revealed formation of strong aOE (c) 311 > texture in a lower growth rate regime, aOE (c) 110 > and ``rotated aOE (c) 110 > aEuroe in an intermediate growth regime, and aOE (c) 112 > in a higher growth rate regime. In-depth analysis of the atomic configuration of a solid-liquid interface revealed that the growth texture is influenced by the kinetics of atomic attachment to the solid-liquid interface, which is intimately related to a planar packing fraction and an atomic stacking sequence of the interfacial plane. The mechanism proposed in this article is novel and will be useful in addressing the orientation selection mechanism of topologically closed packed intermetallic systems. The samples grown at a higher growth rate exhibit larger magnetostriction (lambda) and d lambda/dH owing to the absence of pro-peritectic (Tb,Dy)Fe-3 and formation of aOE (c) 112 > texture, which lies closer to the easy magnetization direction (EMD).

PMMA with Long-Persistent Phosphors and Its Behavior of Luminescence

A new kind of rare earth material with high efficient long-persistent phosphors, such as SrAl2O4: Eu, Dy, has been developed in recent years. The PMMA with long-persistent phosphors is typical one of applications for the phosphors. In this work, we try to probe into the affection of the manufacture process on the PMMA with long-persistent phosphors, to analyze its performance, and its luminescence behavior, especially to study the self-excitation of the PMMA with long-persistent phosphors.

Viscosity, Surface Tension, and Atomization of Water-Methanol and Diesel Emulsions

This article is the result of experimental studies of the rheologv, viscosities, surface tensions, and atomization of water-methanol and diesel emulsions. The Span 80 and Tween 60 are employed to make three emulsifying agents, Y01, Y02, and Y03, with viscosity of 1.32-1.5 Pa s and HLB values of 5.36, 4.83, and 4.51, respectively. In the water-in-oil emulsions, the aqueous phase is between 10% and 50%; the agent concentration added is 0.8-8.0%. The viscosity of the emulsions is 0.003-0.02 Pa s, and the surface tens ion is 0.04-0.1 N/m. The types and concentrations of agents significantly influence the viscosity of the emulsions, and the higher concentration of the aqueous phase (<50%) in creases the viscosities of the emulsions, especially for higher agent concentration. Interfacial membrane and HLB values of the agents can explain all these phenomena. Higher aqueous phase concentration and agent viscosity results in larger Sauter mean diameter.

The CU-HTK Mandarin broadcast news transcription system

This paper discusses the development of the CU-HTK Mandarin Broadcast News (BN) transcription system. The Mandarin BN task includes a significant amount of English data. Hence techniques have been investigated to allow the same system to handle both Mandarin and English by augmenting the Mandarin training sets with English acoustic and language model training data. A range of acoustic models were built including models based on Gaussianised features, speaker adaptive training and feature-space MPE. A multi-branch system architecture is described in which multiple acoustic model types, alternate phone sets and segmentations can be used in a system combination framework to generate the final output. The final system shows state-of-the-art performance over a range of test sets. ©2006 British Crown Copyright.

Dynamics Of Fine Particles In Liquid-Solid Fluidized Beds

On the basis of the Local Equilibrium Model (LEM), fine particles with large Richardson-Zaki exponent n show, under certain conditions during bed expansion and collapse, different dynamic behavior from particles with small n. For an expansion process there may be a concentration discontinuity propagating upward from the distributor, and, on the contrary, for a collapse process there may be a progressively broadening and upward-propagating continuous transition zone instead of discontinuity. The predictions of the bed height variation and the discontinuity trace have been validated experimentally. (c) 2007 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Two-Dimensional Kinetics Of Beta(2)-Integrin And Icam-1 Bindings Between Neutrophils And Melanoma Cells In A Shear Flow

Cell adhesion, mediated by specific receptor-ligand interactions, plays an important role in biological processes such as tumor metastasis and inflammatory cascade. For example, interactions between beta(2)-integrin ( lymphocyte function-associated antigen-1 and/or Mac-1) on polymorphonuclear neutrophils (PMNs) and ICAM-1 on melanoma cells initiate the bindings of melanoma cells to PMNs within the tumor microenvironment in blood flow, which in turn activate PMN-melanoma cell aggregation in a near-wall region of the vascular endothelium, therefore enhancing subsequent extravasation of melanoma cells in the microcirculations. Kinetics of integrin-ligand bindings in a shear flow is the determinant of such a process, which has not been well understood. In the present study, interactions of PMNs with WM9 melanoma cells were investigated to quantify the kinetics of beta(2)-integrin and ICAM-1 bindings using a cone-plate viscometer that generates a linear shear flow combined with a two-color flow cytometry technique. Aggregation fractions exhibited a transition phase where it first increased before 60 s and then decreased with shear durations. Melanoma-PMN aggregation was also found to be inversely correlated with the shear rate. A previously developed probabilistic model was modified to predict the time dependence of aggregation fractions at different shear rates and medium viscosities. Kinetic parameters of beta(2)-integrin and ICAM-1 bindings were obtained by individual or global fittings, which were comparable to respectively published values. These findings provide new quantitative understanding of the biophysical basis of leukocyte-tumor cell interactions mediated by specific receptor-ligand interactions under shear flow conditions.

Novel experimental phenomena of fine-particle fluidized beds

The dynamic response of bed height and concentration waves in liquid-solid fluidized beds to a step change in the fluidization velocity is considered. We experimentally study the liquid-solid fluidized beds, spherical beadings, with sizes ranging from 230 to 270 mesh and the inner diameter of columns made from glass is 2.4 mm. Experimental results find that under certain conditions, fine particles with large Richardson-Zaki exponent n display different dynamic behavior from usual particles with smaller n during expansion and collapse of the fluidized state. (c) 2007 Elsevier Inc. All rights reserved.

以1-苯基-3-甲基-4-苯甲酰基代吡唑酮[5]萃取稀土和钍铀钛锆及其在分析化学中的某些应用

本文研究了以PMBP-苯萃取稀土和钍、铀、钛、锆的萃取行为。测定了La、Ce、Pr、Nd、Sm、Gd、Dy、Yb、Y、U(Ⅵ)、Ti、Th和Zr的pH_(1/2)值,计算了它们的萃取平衡常数。并介绍了近十年来作者将此萃取剂应用于铀、钍、稀土、鋰、钢铁合金及岩石中痕量稀土、钍和钙的分离和测定方面的工作。实践证明,PMOP合成简便、价格低廉、萃取能力较强,是比TTA更为优越的萃取剂。