Nghiem Nguyen - Academia.edu (original) (raw)
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Thai Nguyen University of Agriculture and Forestry
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Papers by Nghiem Nguyen
MATERIALS TRANSACTIONS, 2015
Cadmium(II) is not only hazardous but is also an impurity in the leachate of electronic waste whi... more Cadmium(II) is not only hazardous but is also an impurity in the leachate of electronic waste which is processed during the extraction of valuable metals. This research focuses on the removal of cadmium from the leachate of e-waste containing Cu, Ni, Sn, Pb, Cd, Zn and Au using a solvent impregnated resin (SIR). The studies performed for the extraction of cadmium from the high acidity chloride solution showed the effective removal of cadmium forming solvation compound with Cyanex 923 impregnated Amberlite XAD-7HP resin. In the adsorption studies, the kinetics was found to be a second-order rate and followed a Langmuir isotherm. The results also showed that SIR comprising Cyanex 923 is effective for adsorption of zinc and gold from the leachate. The loaded metals on the SIR were separated by using selective eluents, water for Cd and Zn, whereas thiourea eluted Au. The remaining metals in the raffinate could be further processed to recover valuables after removing cadmium and other metals by a suitable hydrometallurgical processes.
Journal of Mathematical Physics, 2013
In this manuscript, we consider the Cauchy problem for a Schrödinger system with power-type nonli... more In this manuscript, we consider the Cauchy problem for a Schrödinger system with power-type nonlinearities i ∂ ∂t u j + u j + m k=1 a jk |u k | p |u j | p−2 u j = 0, u j (x, 0) = ψ j0 (x), where u j : R N × R → C, ψ j0 : R N → C for j = 1, 2,. .. , m and a jk = a kj are positive real numbers. Global existence for the Cauchy problem is established for a certain range of p. A sharp form of a vector-valued Gagliardo-Nirenberg inequality is deduced, which yields the minimal embedding constant for the inequality. Using this minimal embedding constant, global existence for small initial data is shown for the critical case p = 1 + 2/N. Finite-time blow-up, as well as stability of solutions in the critical case, is discussed.
SIAM Journal on Applied …, 2010
We study the spectral (in)stability of one-dimensional solitary and cnoidal waves of various Bous... more We study the spectral (in)stability of one-dimensional solitary and cnoidal waves of various Boussinesq systems. These systems model three-dimensional water waves (i.e., the surface is two dimensional) with or without surface tension. We present the results of numerous computations examining the spectra related to the linear stability problem for both stationary solitary and cnoidal waves with various amplitudes, as well as multi-pulse solutions. The one-dimensional nature of the wave forms allows us to separate the dependence of the perturbations on the spatial variables by transverse wave number. The compilation of these results gives a full view of the two-dimensional stability problem of these one-dimensional solutions. We demonstrate that line solitary waves with elevated profiles are spectrally stable with respect to one-dimensional perturbations and long transverse perturbations. We show that depression solitary waves are spectrally stable with respect to one-dimensional perturbations, but unstable with respect to transverse perturbations. We also discuss the instability of multi-pulse solitary waves and cnoidal-wave solutions of the Boussinesq system.
MATERIALS TRANSACTIONS, 2015
Cadmium(II) is not only hazardous but is also an impurity in the leachate of electronic waste whi... more Cadmium(II) is not only hazardous but is also an impurity in the leachate of electronic waste which is processed during the extraction of valuable metals. This research focuses on the removal of cadmium from the leachate of e-waste containing Cu, Ni, Sn, Pb, Cd, Zn and Au using a solvent impregnated resin (SIR). The studies performed for the extraction of cadmium from the high acidity chloride solution showed the effective removal of cadmium forming solvation compound with Cyanex 923 impregnated Amberlite XAD-7HP resin. In the adsorption studies, the kinetics was found to be a second-order rate and followed a Langmuir isotherm. The results also showed that SIR comprising Cyanex 923 is effective for adsorption of zinc and gold from the leachate. The loaded metals on the SIR were separated by using selective eluents, water for Cd and Zn, whereas thiourea eluted Au. The remaining metals in the raffinate could be further processed to recover valuables after removing cadmium and other metals by a suitable hydrometallurgical processes.
Journal of Mathematical Physics, 2013
In this manuscript, we consider the Cauchy problem for a Schrödinger system with power-type nonli... more In this manuscript, we consider the Cauchy problem for a Schrödinger system with power-type nonlinearities i ∂ ∂t u j + u j + m k=1 a jk |u k | p |u j | p−2 u j = 0, u j (x, 0) = ψ j0 (x), where u j : R N × R → C, ψ j0 : R N → C for j = 1, 2,. .. , m and a jk = a kj are positive real numbers. Global existence for the Cauchy problem is established for a certain range of p. A sharp form of a vector-valued Gagliardo-Nirenberg inequality is deduced, which yields the minimal embedding constant for the inequality. Using this minimal embedding constant, global existence for small initial data is shown for the critical case p = 1 + 2/N. Finite-time blow-up, as well as stability of solutions in the critical case, is discussed.
SIAM Journal on Applied …, 2010
We study the spectral (in)stability of one-dimensional solitary and cnoidal waves of various Bous... more We study the spectral (in)stability of one-dimensional solitary and cnoidal waves of various Boussinesq systems. These systems model three-dimensional water waves (i.e., the surface is two dimensional) with or without surface tension. We present the results of numerous computations examining the spectra related to the linear stability problem for both stationary solitary and cnoidal waves with various amplitudes, as well as multi-pulse solutions. The one-dimensional nature of the wave forms allows us to separate the dependence of the perturbations on the spatial variables by transverse wave number. The compilation of these results gives a full view of the two-dimensional stability problem of these one-dimensional solutions. We demonstrate that line solitary waves with elevated profiles are spectrally stable with respect to one-dimensional perturbations and long transverse perturbations. We show that depression solitary waves are spectrally stable with respect to one-dimensional perturbations, but unstable with respect to transverse perturbations. We also discuss the instability of multi-pulse solitary waves and cnoidal-wave solutions of the Boussinesq system.