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91.
92.
Rui Silva Carvalho Ana L. Daniel‐da‐Silva Tito Trindade 《Particle & Particle Systems Characterization》2016,33(3):150-157
It is demonstrated that colloidal magnetite nanoparticles can be used as nanosorbents for lanthanide ions dissolved in water. In particular, a series of experiments are performed for the removal of Eu(III) in distinct analytical conditions and by applying an external magnet to collect the sorbents previously dispersed in water samples. Furthermore, strategies for surface chemistry functionalization are also investigated, aiming to investigate the effect of this parameter on the removal capacity of the Fe3O4 nanoparticles. The supernatant solutions are monitored for the remaining amount of Eu(III) by fluorescence emission measurements in the presence of 2,6‐pyridinedicarboxylic acid as a sensitizer. The results demonstrate that neat Fe3O4 nanoparticles are capable of capturing lanthanide ions (III) from aqueous solutions (pH 7), without need of surface modification, and for subsequent removal by magnetic separation. During the removal, efficiency is increased after modifying the particles' surfaces with silica and 3‐aminopropyltrimethoxysilane; in alkaline medium (pH 10), there is complete removal regardless the type of nanosorbent used. This has been explained by the formation of insoluble Eu(III) species that adsorb strongly to the nanosorbents surfaces allowing their subsequent magnetic separation. 相似文献
93.
Spontaneous-search method and short-time dynamics: applications to the
Domany-Kinzel cellular automaton 总被引:1,自引:0,他引:1
S. D. da Cunha U. L. Fulco L. R. da Silva F. D. Nobre 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(1):93-100
The one-dimensional Domany-Kinzel cellular automaton is investigated by two
numerical approaches: (i) the spontaneous-search method, which is a method
appropriated for a search of criticality; (ii) short-time dynamics. Both
critical frontiers of the system are investigated, namely, the one
separating the frozen and active phases, as well as the critical line
determined by damage spreading between two cellular automata, that splits
the active phase into the nonchaotic and chaotic phases.
The efficiency of the spontaneous-search method is established herein
through a precise estimate of both critical frontiers, and in addition to
that, it is shown that this method may also be used in the determination
of the critical exponent ν⊥. Using the critical frontiers
obtained, other exponents are estimated through short-time dynamics. It is
verified that the critical exponents of both critical frontiers fall in the
universality class of directed percolation. 相似文献
94.
Fábio Dahia Carlos Romero Lúcio F. P. da Silva Reza Tavakol 《General Relativity and Gravitation》2008,40(6):1341-1351
We study the classical geodesic motions of nonzero rest mass test particles and photons in (3 + 1 + n)- dimensional warped product spaces. An important feature of these spaces is that they allow a natural decoupling between
the motions in the (3 + 1)-dimensional spacetime and those in the extra n dimensions. Using this decoupling and employing phase space analysis we investigate the conditions for confinement of particles
and photons to the (3 + 1)- spacetime submanifold. In addition to providing information regarding the motion of photons, we
also show that these motions are not constrained by the value of the extrinsic curvature. We obtain the general conditions
for the confinement of geodesics in the case of pseudo-Riemannian manifolds as well as establishing the conditions for the
stability of such confinement. These results also generalise a recent result of the authors concerning the embeddings of hypersurfaces
with codimension one. 相似文献
95.
对全加器概念进行了推广,并在此基础上给出了使用字节全加器网络的无线电抗干扰算法。通过在实际的无线电测控系统中的应用,结果表明该算法具有良好的无线电抗干扰效果。 相似文献
96.
Mössbauer spectroscopy is applied to identify the iron contents of bony elements of southern Brazilian Triassic reptile remains, and the question of the paragenetic mineral assemblage is discussed. 相似文献
97.
T. Missana C. N. Afonso M. F. da Silva 《Applied Physics A: Materials Science & Processing》1994,59(6):653-658
Interdiffusion processes are induced by nanosecond laser pulses from an excimer laser. The Bi-based systems studied are formed by a Bi layer and a Sb or Ge layer. Configurations with Bi at the surface layer or at the innermost layer are both studied. Real-time reflectivity measurements are performed during the irradiation to determine the process kinetics and times and Rutherford backscattering spectrometry is used to obtain the concentration depth profiles. It will be shown that there is an interfacially initiated diffusion process in the Bi-Sb system and that the diffusion coefficients of this system within the liquid phase are in the 10–5–10–6 cm2/s range. The Bi-Ge system shows instead little mixing, the diffusion coefficients of the system within the liquid phase being at least two orders of magnitude lower. The differences observed when Bi is the surface layer or the innermost one are related to the different thermal responses of the system. 相似文献
98.
Jos�� Fl��vio Marcelino Borges Marlon Luiz Hneda Andr�� Maur��cio Brinatti Jo?o Batista Marimon da Cunha Jadir Aparecido Rosa Jos�� Domingos Fabris 《Hyperfine Interactions》2011,203(1-3):9-15
A sample of the coarse sand fraction from the soil material of the A-horizon (0?C0.2 m from the soil surface) of a dusky red magnetic Oxisol was submitted to high-energy mechanical milling for different times. This assay aimed mainly at (a) monitoring the individualization of strongly aggregated mineral particles, and (b) measuring the effect of the milling pressure on the mineralogy changes of the material. These data are also intended to experimentally subside any physical model describing the mechanical behavior of the superficial soil layer that is subjected to intensive machine management, in agriculture fields. Powder X-ray data reveal that some mineralogical phases, notably gibbsite, disappear soon after the first few hours milling. The 298 K-transmission Mössbauer spectrum for the non-milled sand sample shows a qualitatively typical pattern for the sand fraction of basalt derived soils, with magnetically ordered sextets, assignable mainly to hematite and maghemite, and an intense central (super)paramagnetic Fe3?+? doublet. For the milled samples, spectra revealed progressive spectral reduction of the magnetic hyperfine structure, with concomitant increase of relative subspectral areas due to (super)paramagnetic phases, as the milling time increased. This result is consistent with the reduction of measured saturation magnetization, from 4.96(8) J T???1 kg???1, for the non-milled sample, to 3.26(7) J T???1 kg???1, for the sample milled for 8 hours. 相似文献
99.
M. ElMassalami D. da S. OliveiraH. Takeya 《Journal of magnetism and magnetic materials》2011,323(16):2133-2136
Based on extensive Mossbauer effect (ME) and magnetization measurements, the orthorhombic AlFe2B2 was characterized as a ferromagnet (FM) because this character is evident as an onset of a FM transition at Tc=320 K and characteristic magnetizations isotherms below Tc. At liquid helium temperatures, the magnetization saturates to μsat≈1μB per Fe atom; a value which is half the one reported for the iron metal indicating a relatively more filled 3d band. The ME analysis revealed a hyperfine field H(0) of 88(2) kOe, an isomer shift (relative to Fe) of 0.50(2) mm/s, and a quadrupole parameter of 0.02 mm/s: all parameters extrapolated to zero Kelvin. The itinerant character of the magnetic moment will be discussed. 相似文献
100.
Measurements of electrical conductivity and thermal behaviour have been carried out on polymer electrolyte films obtained
by the addition of erbium triflate to poly(ethylene oxide), PEO. Homogeneous electrolyte samples were prepared by using solvent
casting and hot-pressing techniques to produce films with a composition defined by the general formula (EO)nEr(CF3SO3)3, where n lies between 3 and 150.
This electrolyte system was found to behave in a manner broadly similar to other trivalent salt containing polymer electrolytes,
however, in contrast to previously studied lanthanide systems, a salt - polymer complex crystallized after prolonged annealing
of salt rich compositions at room temperature.
Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10 – 16, 1995 相似文献