Nguyen Vinh Phuc (FGW HCM) (original) (raw)

Papers by Nguyen Vinh Phuc (FGW HCM)

Research paper thumbnail of Characterizations of signed measures in the dual of BV and related isometric isomorphisms

ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE

We characterize all (signed) measures in BV n n−1 (R n) * , where BV n n−1 (R n) is defined as th... more We characterize all (signed) measures in BV n n−1 (R n) * , where BV n n−1 (R n) is defined as the space of all functions u in L n n−1 (R n) such that Du is a finite vector-valued measure. We also show that BV n n−1 (R n) * and BV (R n) * are isometrically isomorphic, where BV (R n) is defined as the space of all functions u in L 1 (R n) such that Du is a finite vector-valued measure. As a consequence of our characterizations, an old issue raised in Meyers-Ziemer [16] is resolved by constructing a locally integrable function f such that f belongs to BV (R n) * but |f | does not. Moreover, we show that the measures in BV n n−1 (R n) * coincide with the measures inẆ 1,1 (R n) * , the dual of the homogeneous Sobolev spaceẆ 1,1 (R n), in the sense of isometric isomorphism. For a bounded open set Ω with Lipschitz boundary, we characterize the measures in the dual space BV 0 (Ω) *. One of the goals of this paper is to make precise the definition of BV 0 (Ω), which is the space of functions of bounded variation with zero trace on the boundary of Ω. We show that the measures in BV 0 (Ω) * coincide with the measures in W 1,1 0 (Ω) *. Finally, the class of finite measures in BV (Ω) * is also characterized.

Research paper thumbnail of Optimal Income Taxation with Uncertain Factors

Research paper thumbnail of Dimer Hóa Protein Dung Hợp Với Rhau Bởi Cấu Trúc G-Quadruplex Song Song

Research paper thumbnail of Weighted estimates for nonhomogeneous quasilinear equations with discontinuous coefficients

ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE, 2011

We obtain local and global W 1, q estimates on weighted Lebesgue spaces with certain Muckenhoupt ... more We obtain local and global W 1, q estimates on weighted Lebesgue spaces with certain Muckenhoupt weights for solutions to a nonhomogeneous p-Laplace type equation with V M O coefficients in a C 1 domain. These estimates can be viewed as weighted norm inequalities for certain nonlinear singular operators (without any explicit kernel) arising from the p-Laplacian, and are applicable to a quasilinear Riccati type equation.

Research paper thumbnail of The Role of Anisotropy in Distinguishing Domination of Néel or Brownian Relaxation Contribution to Magnetic Inductive Heating: Orientations for Biomedical Applications

Materials, 2021

Magnetic inductive heating (MIH) has been a topic of great interest because of its potential appl... more Magnetic inductive heating (MIH) has been a topic of great interest because of its potential applications, especially in biomedicine. In this paper, the parameters characteristic for magnetic inductive heating power including maximum specific loss power (SLPmax), optimal nanoparticle diameter (Dc) and its width (ΔDc) are considered as being dependent on magnetic nanoparticle anisotropy (K). The calculated results suggest 3 different Néel-domination (N), overlapped Néel/Brownian (NB), and Brownian-domination (B) regions. The transition from NB- to B-region changes abruptly around critical anisotropy Kc. For magnetic nanoparticles with low K (K < Kc), the feature of SLP peaks is determined by a high value of Dc and small ΔDc while those of the high K (K > Kc) are opposite. The decreases of the SLPmax when increasing polydispersity and viscosity are characterized by different rates of d(SLPmax)/dσ and d(SLPmax)/dη depending on each domination region. The critical anisotropy Kc va...

Research paper thumbnail of Variation of Dissolved Oxygen in the Flooding Water of the Paddy Fields

Journal of the Faculty of Agriculture, Kyushu University, 1975

The experimental measurements were carried out of DO (dissolved oxygen) in the flooding water of ... more The experimental measurements were carried out of DO (dissolved oxygen) in the flooding water of lysimeters, paddy fields and creeks during the rice planting seasons in 1973 and 1974. The DO diurnal curves were obtained under various conditions of the water bodies. Accordingly, the DO variation in the flooding water of the paddy fields is mostly attributable to the source and sink due to the metabolic activities of aquatic organisms in the water. It is noted that in the day time, the DO increases with the intensity of diurnal solar radiation and the maximum values of DO can attain more than 200 percent to the saturation index. On the other hand, after sun set, the DO steeply falls toward the values about 50 percent or less to the saturation index. The DO change rate f(t) and its components p(t), h(t) and e(t) can be evaluated, where p(t) is the DO production rate, h(t) is the DO consumption rate and e(t) is the DO-O2 exchange rate between atmosphere and water. As understanding these factors, it is possible to recognize that p(t) is dependent on the photosynthetic activity of green algae and h(t) is ascribable to the chemical and biological absorptions. It is clear to obtain that the daily DO production P and daily DO consumption H increase under the condition of large density of green algae at raised intensity of solar radiation, whereas both P and H decrease provided that small density of green algae in the flooding water of paddy fields.

Research paper thumbnail of Mathematical Analysis on the Miscible Displacement and Diffusion of Dissolved Oxygen in the Submerged Soils

Journal of the Faculty of Agriculture, Kyushu University, 1976

The submerged paddy soils are characterized by the very small oxygen concentration throughout the... more The submerged paddy soils are characterized by the very small oxygen concentration throughout the soil profile. The oxidized zone below the ground surface has the thickness which depends on the chemical and biological circumstances of the soil medium. In the paddy field, dissolved oxygen in the overlying ffooding water can be transferred into the submerged soil by miscible displacement and diffusion. The phenomenon of miscible displacement takes place when dissolved oxygen in the percolating water is transferred through the soil medium by mass transport and by diffusion. The mathematical models of miscible displacement and diffusion are used to elucidate the mechanism of dissolved oxygen in the submerged soils. AS for the various acceptable models, three are concerned. For model (1) and model (Z), the results are very fitting between the calculations from the theoretical solutions and the experiments by using the long column of submerged sand in the laboratory. For model (3), the calculated results bring again a very meaningful interpretation for the vertical distribution of DO in the submerged media, when DO in the overlying flooding water is the indefinite function of time, Particularly, for the submerged clayey paddy soil, in which, the percolating velocity is very small and the consumption rate of oxygen is very large. Since the growth of horizontal roots of rice plants may rely on dissolved oxygen, the present of which in the surface flooding water and in the oxidized zone of submerged soil is essential.

Research paper thumbnail of Regulation of aspartokinase III synthesis in Escherichia coli: isolation of mutants containing lysC-lac fusions

Journal of Bacteriology, 1980

Mutants containing fusions of the lac gene to the lysC gene were isolated. In these, the expressi... more Mutants containing fusions of the lac gene to the lysC gene were isolated. In these, the expression of ,B-galactosidase was regulated by lysine (and arginine), as previously described for aspartokinase III.

Research paper thumbnail of Towards efficient extraction of La(III) from spent FCC catalysts by alkaline pre-treatment

Minerals Engineering, 2018

In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFC... more In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFCC) catalysts per year. The recovery of rare earth metals (La(III), Ce(III),…) contained in SFCC catalysts using acid leaching process has attracted much attention of scientific community. In this study, the effect of alkaline pre-treatment of spent catalysts prior to the acid leaching process on the leaching yield of La(III) was investigated. The results showed that alkaline pre-treatment caused zeolite destruction, which had a positive effect on the leaching of La (III). High leaching yields of La(III), 80% and 86%, were achieved when the SFCC catalysts were pre-treated with NaOH and NH 3 , respectively, before leaching with 2 M HNO 3 solution at 50°C. These results were comparable with the one obtained from the sample that was leached by 7 M HNO 3 at 50°C without the initial alkaline pretreatment. NH 3 pre-treatment significantly enhanced the zeolite destruction in the SFCC catalysts and increased La(III) leaching yield compared to the NaOH pre-treatment. It is likely due to NH 3 interactions with contaminant metals (e.g. Ni, V, and Fe), which were deposited on catalysts during cracking process.

Research paper thumbnail of Firm’s Strategic Responses in Standardization

Journal on Innovation and Sustainability. RISUS ISSN 2179-3565, 2014

From the perspective of game theory, this paper examines 1) Why do companiesparticipate in standa... more From the perspective of game theory, this paper examines 1) Why do companiesparticipate in standardization activities and patent pools, even if the activities benefit their rivalcompanies; 2) When there are multiple standards of similar products, under what conditionswill these multiple standards be replaced by a de facto standard, 3) When will these multiplestandards coexist together? 4) What are the strategic responses of the companies then?

Research paper thumbnail of Raman Observation of Silicomolybdic Acid Formation Derived from H2MoO4 and Excess Tetraethylorthosilicate Using Hydrothermal Sol-gel Method

Journal of the Japan Petroleum Institute, 2012

In order to develop the preparation procedure for silicomolybdic acid (H4SiMo12O40, SMA) on silic... more In order to develop the preparation procedure for silicomolybdic acid (H4SiMo12O40, SMA) on silica catalysts, H2MoO4 and excess tetraethylorthosilicate (TEOS) are employed as starting reagents and three catalysts with different loadings are prepared by a hydrothermal sol-gel method. From Raman measurements in the course of the preparation steps, Raman spectra imply the formation of beta type silicomolybdic acid (β-SMA) reported by M. A. Bañares et al.; Raman spectroscopy suggests that the SMA species are formed in the precursor solution and is stable on 14.6 and 20 wt% MoO3/SiO2 even in the drying process (110). When the loading is 7.9 wt%, Raman peaks of SMA disappear after the hydrothermal treatment at 100. The structural distortion of the SMA due to hydrogen interaction between OH groups and Mo=O bonds is also observed. Raman measurement indicates the transformation to βand α-MoO3 in 20 wt% MoO3/SiO2 after the calcination at 500 , but only surface molybdates are observed at the loadings of 7.9 and 14.6 wt%. The results indicate that H2MoO4 is also effective for the simple preparation of SMA. In addition, as no XRD patterns of all Mo species are observed, Raman spectroscopy is an effective method to structural analysis of Mo species, even in liquid and wet samples.

Research paper thumbnail of Individual nerve fibre selective blocking method and appliance

Research paper thumbnail of Magnetic anomalies of polycrystalline La2Col.7 compound in the temperature range 5-400 K

Journal of Magnetism and Magnetic Materials, 1998

Research paper thumbnail of Peak effect in NdBa 2Cu 3O 7- d superconductor and related Raman spectra

Research paper thumbnail of First-Order Quantum Phase Transition in Bose Gases

The Bogoliubov theory has proven to be an accurate and versatile tool in the study of weaklyinter... more The Bogoliubov theory has proven to be an accurate and versatile tool in the study of weaklyinteracting dilute Bose gases at low temperatures, yet there is one exception where it goes qualitatively wrong, i.e., near the first-order quantum phase transitions. By examining a phase transition in spinor Bose-Einstein condensates (BECs), we find that the energy spectrum given by the Bogoliubov theory is inconsistent with the fact that the phase transition is first order. We resolve this problem by calculating the spectrum based on the spinor version of the Beliaev theory. We also discuss the ground-state phase diagram of spin-2 BECs which is modified by quantum fluctuations and the possibility of macroscopic quantum tunneling near the cyclic-nematic phase boundary.

Research paper thumbnail of Concrete boundary of Thang Long castle under the le dynasty found in literary materials

Vietnam Social Sciences, 2005

Research paper thumbnail of Handicrafts of thang long

Vietnam Social Sciences, 2002

Research paper thumbnail of A reconsideration of the optimal income tax model from the asymmetric information aspect

Research paper thumbnail of The use of orthogonal polynomials in all-pole filter design

Research paper thumbnail of An end-point global gradient weighted estimate for quasilinear equations in non-smooth domains

Manuscripta Mathematica, 2015

A weighted norm inequality involving A1 weights is obtained at the natural exponent for gradients... more A weighted norm inequality involving A1 weights is obtained at the natural exponent for gradients of solutions to quasilinear elliptic equations in Reifenberg flat domains. Certain gradient estimates in Lorentz-Morrey spaces below the natural exponent are also obtained as a consequence of our analysis.

Research paper thumbnail of Characterizations of signed measures in the dual of BV and related isometric isomorphisms

ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE

We characterize all (signed) measures in BV n n−1 (R n) * , where BV n n−1 (R n) is defined as th... more We characterize all (signed) measures in BV n n−1 (R n) * , where BV n n−1 (R n) is defined as the space of all functions u in L n n−1 (R n) such that Du is a finite vector-valued measure. We also show that BV n n−1 (R n) * and BV (R n) * are isometrically isomorphic, where BV (R n) is defined as the space of all functions u in L 1 (R n) such that Du is a finite vector-valued measure. As a consequence of our characterizations, an old issue raised in Meyers-Ziemer [16] is resolved by constructing a locally integrable function f such that f belongs to BV (R n) * but |f | does not. Moreover, we show that the measures in BV n n−1 (R n) * coincide with the measures inẆ 1,1 (R n) * , the dual of the homogeneous Sobolev spaceẆ 1,1 (R n), in the sense of isometric isomorphism. For a bounded open set Ω with Lipschitz boundary, we characterize the measures in the dual space BV 0 (Ω) *. One of the goals of this paper is to make precise the definition of BV 0 (Ω), which is the space of functions of bounded variation with zero trace on the boundary of Ω. We show that the measures in BV 0 (Ω) * coincide with the measures in W 1,1 0 (Ω) *. Finally, the class of finite measures in BV (Ω) * is also characterized.

Research paper thumbnail of Optimal Income Taxation with Uncertain Factors

Research paper thumbnail of Dimer Hóa Protein Dung Hợp Với Rhau Bởi Cấu Trúc G-Quadruplex Song Song

Research paper thumbnail of Weighted estimates for nonhomogeneous quasilinear equations with discontinuous coefficients

ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE, 2011

We obtain local and global W 1, q estimates on weighted Lebesgue spaces with certain Muckenhoupt ... more We obtain local and global W 1, q estimates on weighted Lebesgue spaces with certain Muckenhoupt weights for solutions to a nonhomogeneous p-Laplace type equation with V M O coefficients in a C 1 domain. These estimates can be viewed as weighted norm inequalities for certain nonlinear singular operators (without any explicit kernel) arising from the p-Laplacian, and are applicable to a quasilinear Riccati type equation.

Research paper thumbnail of The Role of Anisotropy in Distinguishing Domination of Néel or Brownian Relaxation Contribution to Magnetic Inductive Heating: Orientations for Biomedical Applications

Materials, 2021

Magnetic inductive heating (MIH) has been a topic of great interest because of its potential appl... more Magnetic inductive heating (MIH) has been a topic of great interest because of its potential applications, especially in biomedicine. In this paper, the parameters characteristic for magnetic inductive heating power including maximum specific loss power (SLPmax), optimal nanoparticle diameter (Dc) and its width (ΔDc) are considered as being dependent on magnetic nanoparticle anisotropy (K). The calculated results suggest 3 different Néel-domination (N), overlapped Néel/Brownian (NB), and Brownian-domination (B) regions. The transition from NB- to B-region changes abruptly around critical anisotropy Kc. For magnetic nanoparticles with low K (K < Kc), the feature of SLP peaks is determined by a high value of Dc and small ΔDc while those of the high K (K > Kc) are opposite. The decreases of the SLPmax when increasing polydispersity and viscosity are characterized by different rates of d(SLPmax)/dσ and d(SLPmax)/dη depending on each domination region. The critical anisotropy Kc va...

Research paper thumbnail of Variation of Dissolved Oxygen in the Flooding Water of the Paddy Fields

Journal of the Faculty of Agriculture, Kyushu University, 1975

The experimental measurements were carried out of DO (dissolved oxygen) in the flooding water of ... more The experimental measurements were carried out of DO (dissolved oxygen) in the flooding water of lysimeters, paddy fields and creeks during the rice planting seasons in 1973 and 1974. The DO diurnal curves were obtained under various conditions of the water bodies. Accordingly, the DO variation in the flooding water of the paddy fields is mostly attributable to the source and sink due to the metabolic activities of aquatic organisms in the water. It is noted that in the day time, the DO increases with the intensity of diurnal solar radiation and the maximum values of DO can attain more than 200 percent to the saturation index. On the other hand, after sun set, the DO steeply falls toward the values about 50 percent or less to the saturation index. The DO change rate f(t) and its components p(t), h(t) and e(t) can be evaluated, where p(t) is the DO production rate, h(t) is the DO consumption rate and e(t) is the DO-O2 exchange rate between atmosphere and water. As understanding these factors, it is possible to recognize that p(t) is dependent on the photosynthetic activity of green algae and h(t) is ascribable to the chemical and biological absorptions. It is clear to obtain that the daily DO production P and daily DO consumption H increase under the condition of large density of green algae at raised intensity of solar radiation, whereas both P and H decrease provided that small density of green algae in the flooding water of paddy fields.

Research paper thumbnail of Mathematical Analysis on the Miscible Displacement and Diffusion of Dissolved Oxygen in the Submerged Soils

Journal of the Faculty of Agriculture, Kyushu University, 1976

The submerged paddy soils are characterized by the very small oxygen concentration throughout the... more The submerged paddy soils are characterized by the very small oxygen concentration throughout the soil profile. The oxidized zone below the ground surface has the thickness which depends on the chemical and biological circumstances of the soil medium. In the paddy field, dissolved oxygen in the overlying ffooding water can be transferred into the submerged soil by miscible displacement and diffusion. The phenomenon of miscible displacement takes place when dissolved oxygen in the percolating water is transferred through the soil medium by mass transport and by diffusion. The mathematical models of miscible displacement and diffusion are used to elucidate the mechanism of dissolved oxygen in the submerged soils. AS for the various acceptable models, three are concerned. For model (1) and model (Z), the results are very fitting between the calculations from the theoretical solutions and the experiments by using the long column of submerged sand in the laboratory. For model (3), the calculated results bring again a very meaningful interpretation for the vertical distribution of DO in the submerged media, when DO in the overlying flooding water is the indefinite function of time, Particularly, for the submerged clayey paddy soil, in which, the percolating velocity is very small and the consumption rate of oxygen is very large. Since the growth of horizontal roots of rice plants may rely on dissolved oxygen, the present of which in the surface flooding water and in the oxidized zone of submerged soil is essential.

Research paper thumbnail of Regulation of aspartokinase III synthesis in Escherichia coli: isolation of mutants containing lysC-lac fusions

Journal of Bacteriology, 1980

Mutants containing fusions of the lac gene to the lysC gene were isolated. In these, the expressi... more Mutants containing fusions of the lac gene to the lysC gene were isolated. In these, the expression of ,B-galactosidase was regulated by lysine (and arginine), as previously described for aspartokinase III.

Research paper thumbnail of Towards efficient extraction of La(III) from spent FCC catalysts by alkaline pre-treatment

Minerals Engineering, 2018

In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFC... more In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFCC) catalysts per year. The recovery of rare earth metals (La(III), Ce(III),…) contained in SFCC catalysts using acid leaching process has attracted much attention of scientific community. In this study, the effect of alkaline pre-treatment of spent catalysts prior to the acid leaching process on the leaching yield of La(III) was investigated. The results showed that alkaline pre-treatment caused zeolite destruction, which had a positive effect on the leaching of La (III). High leaching yields of La(III), 80% and 86%, were achieved when the SFCC catalysts were pre-treated with NaOH and NH 3 , respectively, before leaching with 2 M HNO 3 solution at 50°C. These results were comparable with the one obtained from the sample that was leached by 7 M HNO 3 at 50°C without the initial alkaline pretreatment. NH 3 pre-treatment significantly enhanced the zeolite destruction in the SFCC catalysts and increased La(III) leaching yield compared to the NaOH pre-treatment. It is likely due to NH 3 interactions with contaminant metals (e.g. Ni, V, and Fe), which were deposited on catalysts during cracking process.

Research paper thumbnail of Firm’s Strategic Responses in Standardization

Journal on Innovation and Sustainability. RISUS ISSN 2179-3565, 2014

From the perspective of game theory, this paper examines 1) Why do companiesparticipate in standa... more From the perspective of game theory, this paper examines 1) Why do companiesparticipate in standardization activities and patent pools, even if the activities benefit their rivalcompanies; 2) When there are multiple standards of similar products, under what conditionswill these multiple standards be replaced by a de facto standard, 3) When will these multiplestandards coexist together? 4) What are the strategic responses of the companies then?

Research paper thumbnail of Raman Observation of Silicomolybdic Acid Formation Derived from H2MoO4 and Excess Tetraethylorthosilicate Using Hydrothermal Sol-gel Method

Journal of the Japan Petroleum Institute, 2012

In order to develop the preparation procedure for silicomolybdic acid (H4SiMo12O40, SMA) on silic... more In order to develop the preparation procedure for silicomolybdic acid (H4SiMo12O40, SMA) on silica catalysts, H2MoO4 and excess tetraethylorthosilicate (TEOS) are employed as starting reagents and three catalysts with different loadings are prepared by a hydrothermal sol-gel method. From Raman measurements in the course of the preparation steps, Raman spectra imply the formation of beta type silicomolybdic acid (β-SMA) reported by M. A. Bañares et al.; Raman spectroscopy suggests that the SMA species are formed in the precursor solution and is stable on 14.6 and 20 wt% MoO3/SiO2 even in the drying process (110). When the loading is 7.9 wt%, Raman peaks of SMA disappear after the hydrothermal treatment at 100. The structural distortion of the SMA due to hydrogen interaction between OH groups and Mo=O bonds is also observed. Raman measurement indicates the transformation to βand α-MoO3 in 20 wt% MoO3/SiO2 after the calcination at 500 , but only surface molybdates are observed at the loadings of 7.9 and 14.6 wt%. The results indicate that H2MoO4 is also effective for the simple preparation of SMA. In addition, as no XRD patterns of all Mo species are observed, Raman spectroscopy is an effective method to structural analysis of Mo species, even in liquid and wet samples.

Research paper thumbnail of Individual nerve fibre selective blocking method and appliance

Research paper thumbnail of Magnetic anomalies of polycrystalline La2Col.7 compound in the temperature range 5-400 K

Journal of Magnetism and Magnetic Materials, 1998

Research paper thumbnail of Peak effect in NdBa 2Cu 3O 7- d superconductor and related Raman spectra

Research paper thumbnail of First-Order Quantum Phase Transition in Bose Gases

The Bogoliubov theory has proven to be an accurate and versatile tool in the study of weaklyinter... more The Bogoliubov theory has proven to be an accurate and versatile tool in the study of weaklyinteracting dilute Bose gases at low temperatures, yet there is one exception where it goes qualitatively wrong, i.e., near the first-order quantum phase transitions. By examining a phase transition in spinor Bose-Einstein condensates (BECs), we find that the energy spectrum given by the Bogoliubov theory is inconsistent with the fact that the phase transition is first order. We resolve this problem by calculating the spectrum based on the spinor version of the Beliaev theory. We also discuss the ground-state phase diagram of spin-2 BECs which is modified by quantum fluctuations and the possibility of macroscopic quantum tunneling near the cyclic-nematic phase boundary.

Research paper thumbnail of Concrete boundary of Thang Long castle under the le dynasty found in literary materials

Vietnam Social Sciences, 2005

Research paper thumbnail of Handicrafts of thang long

Vietnam Social Sciences, 2002

Research paper thumbnail of A reconsideration of the optimal income tax model from the asymmetric information aspect

Research paper thumbnail of The use of orthogonal polynomials in all-pole filter design

Research paper thumbnail of An end-point global gradient weighted estimate for quasilinear equations in non-smooth domains

Manuscripta Mathematica, 2015

A weighted norm inequality involving A1 weights is obtained at the natural exponent for gradients... more A weighted norm inequality involving A1 weights is obtained at the natural exponent for gradients of solutions to quasilinear elliptic equations in Reifenberg flat domains. Certain gradient estimates in Lorentz-Morrey spaces below the natural exponent are also obtained as a consequence of our analysis.