Inhomogeneous Ferromagnetism and Spin-Glass-Like Behavior in <inline-formula> <tex-math notation='TeX'> <tex> $({\rm Nd}_{1-x}{\rm Y}_{x})_{0.7}{\rm Sr}_{0.3}{\rm MnO}_{3}$ </tex> </tex-math></inline-formula> With <inline-formula> <tex-math notation='TeX

Phan, T. L.,Nguyen, V. D.,Ho, T. A.,Khiem, N. V.,Thanh, T. D.,Phuc, N. X.,Thang, P. D.,Yu, S. C. IEEE 2014 IEEE transactions on magnetics Vol.50 No.6

<P>The magnetic properties of polycrystalline ceramic samples (Nd1-xYx)(0.7)Sr0.3MnO3 with x = 0.21 - 0.35 were studied by means of dc magnetization and ac susceptibility measurements. Experimental results reveal a strong decrease of the ferromagnetic (FM)-paramagnetic phase-transition temperature (T-C) from 97 to 65 K as increasing x from 0.21 to 0.35, respectively. There is magnetic inhomogeneity associated with short-range FM order. Particularly, the samples undergo a spin-glass (SG) phase transition at the so-called blocking temperature (T-B) below T-C, which shifts toward lower temperatures with increasing the applied field, Hex; T-B -> T-g (the SG phase-transition temperature) as H-ex -> 0. The existence of the SG behavior in these samples was also confirmed by frequency (f) dependences of the ac susceptibility. For the in-phase/real component, chi' (T), it shows a frequency-dependent peak at the SG freezing temperature (T-f); T-f -> T-g as f -> 0. Dynamics of this process were analyzed by means of the slowing down scaling law, tau/tau(0) proportional to (T-f/T-g - 1)(-zv), where tau(0) and zv are the characteristic time and critical exponent, respectively. Fitting the experimental T-f(f) data to the scaling law gave the results of zv = 10.1-12.3 and tau(0) = 10(-21)-10(-15)s. These values are different from those expected for canonical SG systems with zv = 10 and tau(0) = 10(-13)s, revealing the cluster-SG behavior of (Nd1-xYx)(0.7)Sr0.3MnO3 samples. Notably, the increase in Y content leads to the shift of tau(0) and zv values toward those of canonical SG systems, which is ascribed to an expansion of SG clusters.</P>

Magnetocaloric Effect and Critical Behavior of <inline-formula> <tex-math notation='TeX'> <tex> ${\rm Ni}_{42}{\rm Ag}_{8}{\rm Mn}_{37}{\rm Sn}_{13}$ </tex> </tex-math></inline-formula> Alloys

Tran Dang Thanh,Phan, T. L.,Pham Thi Thanh,Nguyen Hai Yen,Nguyen Huy Dan,Yu, S. C. IEEE 2014 IEEE transactions on magnetics Vol.50 No.4

<P>This paper presents the magnetocaloric effect and critical behavior of alloy ingot and ribbon samples of Ni<SUB>50</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> doped with 8% Ag, which were prepared by an arc-melting and rapidly quenched melt-spinning methods, respectively. Experimental results reveal that a partial replacement of Ag for Ni leads to stamping out the antiferromagnetic martensitic phase. This means that there is only the austenitic phase with a ferromagnetic-paramagnetic (FM-PM) phase-transition temperature of T<SUB>C</SUB> ≈ 295 K. Detailed studies and analyses around the phase transition region prove both samples undergoing a second-order magnetic phase transition. Basing on magnetic field dependences of magnetization, we have determined the magnetic-entropy change (ΔS<SUB>m</SUB>) of the samples. Under a field change of 10 kOe, the maximum magnetic-entropy change (|ΔS<SUB>max</SUB>|) reaches values 0.54 and 0.69 J · kg<SUP>-1</SUP> · K<SUP>-1</SUP> for the alloy ingot and ribbon, respectively. Using Landau's phase-transition theory, and careful analyses of the magnetic data around the FM-PM transition region, we have determined the critical parameters (T<SUB>C</SUB>, β, γ, and δ) in the low field range (below 10 kOe) with T<SUB>C</SUB> = 294.8 K, β = 0.469 ± 0.011, γ = 1.149 ± 0.060, and δ = 3.4 ± 0.1 for the alloy ingot, and with T<SUB>C</SUB> = 294.4 K, β = 0.449 ± 0.005, γ = 1.319 ± 0.040, and δ = 3.9 ± 0.1 for the alloy ribbon. One can see that β values fall in between those expected for the 3-D Heisenberg model (β = 0.365) and mean-field theory (β = 0.5). This indicates a coexistence of short-range and long-range FM interactions in both the samples. The nature of changes in value related to the critical parameters and maximum ΔS<SUB>m</SUB> is thoroughly discussed by means of structural analyses.</P>

Second-Order Phase Transition and the Magnetocaloric Effect in <inline-formula> <tex-math notation='TeX'> <tex> ${\rm La}_{{0.7}}{\rm Ca}_{0.3-{x}}{\rm Sr}_{x}{\rm MnO}_{{3}}$ </tex> </tex-math></inline-formula> Nanoparticles

Tran Dang Thanh,Phan, T. L.,Nguyen Van Chien,Do Hung Manh,Yu, S. C. IEEE 2014 IEEE transactions on magnetics Vol.50 No.4

<P>In this paper, we present a detailed study of the magnetocaloric effect and critical properties around the ferromagnetic-paramagnetic (FM-PM) phase transition of La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Sr<SUB>x</SUB>MnO<SUB>3</SUB> nanoparticles with x = 0.10, 0.11, and 0.12. The samples were synthesized by a combination of reactive milling and thermal processing. The average crystallite size of nanoparticles estimated from the linewidth of X-ray diffraction peaks by using the Williamson-Hall method is about 50 nm. Under a magnetic field change of 10 kOe, the maximum magnetic entropy change (|ΔS<SUB>max</SUB>|) reaches values of 1.47, 1.42, and 1.38 J·kg<SUP>-1</SUP>·K<SUP>-1</SUP> for x = 0.10, 0.11, and 0.12, respectively, at around 300 K. The refrigerant capacity is thus in between 44 and 54 J·kg<SUP>-1</SUP>. Particularly, the M<SUP>2</SUP> versus H/M curves prove that all the samples exhibit a second-order magnetic phase transition. Based on Landau's phase-transition theory and careful analyses of the magnetic data around the FM-PM transition region, we have determined the critical exponents β, y, δ, and T<SUB>C</SUB>. Here, the β values obtained are 0.397, 0.453, and 0.456 for x = 0.10, 0.11, and 0.12, respectively, which are in between those expected on the basis of the mean-field theory (β = 0.5) and value of the 3-D Heisenberg model (β = 0.365). The result proves the coexistence of shortand long-range FM interactions in La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Sr<SUB>x</SUB>MnO<SUB>3</SUB> nanoparticles. The nature of this phenomenon is discussed thoroughly.</P>

The evolutionary dynamics of highly pathogenic avian influenza H5N1 in south-central Vietnam reveals multiple clades evolving from Chinese and Cambodian viruses

Nguyen, T.H.,Than, V.T.,Thanh, H.D.,Nguyen, V.Q.,Nguyen, K.H.,Nguyen, D.T.,Park, J.H.,Chung, I.S.,Jeong, D.G.,Chang, K.T.,Oh, T.K.,Kim, W. Pergamon Press 2015 Comparative immunology, microbiology and infectiou Vol.42 No.-

In Vietnam, highly pathogenic avian influenza (HPAI), such as that caused by H5N1 viruses, is the most highly contagious infectious disease that has been affecting domestic poultry in recent years. Vietnam might be an evolutionary hotspot and a potential source of globally pandemic strains. However, few studies have reported viruses circulating in the south-central region of Vietnam. In the present study, 47 H5N1-positive samples were collected from both vaccinated and unvaccinated poultry farms in the South Central Coast region of Vietnam during 2013-2014, and their genetic diversity was analyzed. A common sequence motif for HPAI virus was identified at HA-cleavage sites in all samples: either RERRRKR/G (clades 2.3.2.1c and 2.3.2.1a) or REGRRKKR/G (clade 1.1.2). Phylogenetic analysis of HA genes identified three clades of HPAI H5N1: 1.1.2 (n=1), 2.3.2.1a (n=1), and 2.3.2.1c (n=45). The phylogenetic analysis indicated that these Vietnamese clades may have evolved from Chinese and Cambodian virus clades isolated in 2012-2013 but are less closely related to the clades detected from the Tyva Republic, Bulgaria, Mongolia, Japan, and Korea in 2009-2011. Detection of the coexistence of virus clades 2.3.2.1 and the very virulent 1.1.2 in the south-central regions suggests their local importance and highlights concerns regarding their spread, both northwards and southwards, as well as the potential for reassortment. The obtained data highlight the importance of regular identification of viral evolution and the development and use of region-specific vaccines.

Prescription of nitrogen topdressing rate at panicle initiation stage based on fresh weight and SPAD value

Nguyen Hung T.,Nguyen Thanh D.,Nguyen Lan T.,Nguyen Anh T.,Lee Byun-Woo 한국작물학회 2005 한국작물학회 학술발표대회 논문집 Vol.2005 No.-

Structural Monitoring of a Defective Steel Beam Model Based on Image Changes in Power Spectral Density

Thanh Q. Nguyen,Tuan A. Nguyen,Thuy T. Nguyen 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.4

Using power-spectral density (PSD) analysis for structures, we evaluated defects following a widespread research trend. During the structure’s operation, PSD not only demonstrated its structural integrity at the time of surveying but also predicted future changes in the structure. The present research used changes in PSD as a key feature for monitoring a beam structure’s shearing patterns. Two shearing models—side shearing and shearing under the beam—revealed changes in the shape of PSD images that corresponded to degrees of defect in the diff erent shearing models. We applied these results to the monitoring of simple actual span structures over a long period of time. We monitored the structure’s operational status over time to examine the increased infl uence of structural defects based on signifi cant changes in the PSD regarding spectral amplitude and spectral width. The frequencies initially found in the high-frequency region of PSD tended to shift toward the lower-frequency regions before disappearing entirely. In the future, the results of this research may improve the evaluation of structural integrity through variations of PSD in vibrational spectral shapes.

Monsoonal sediment transport along the subaqueous Mekong Delta: An analysis of surface sediment grain-size changes

Thanh C., Nguyen,An T., Dang,Khuong N.T., Tran Techno-Press 2022 Ocean systems engineering Vol.12 No.4

Annually, about 48-60% of sediment discharge of the Mekong River is delivered near the mouths of the Mekong River branches which is mostly coinciding with the southwest (SW) monsoon. This sediment budget in turn will be southwestwardly transported along the coast of the Mekong Delta (MD) during the northeast (NE) monsoon. Analysis of monsoonal changes in grain-size distribution (GSD) of surface sediment contributes to a better understanding of erosion and deposition processes along the MD. This study aims to figure out changes in GSD and sediment textures along the MD between SW and NE monsoons based on 183 surficial sediment samples collected along the MD during two field surveys carried-out in October 2016 and February-March 2017. Compared to the GSD during the SW and NE monsoon, the GSD along the MD changed significantly, especially in the estuary areas and along the coast of Bac Lieu and Ganh Hao. Whereas, in the west coast of the MD, GSD seem no changes between the two seasons. These changes in seabed sediment suggest that sediment with grain-sizes ranging from silt to fine sand can be transported during only a NE season.

Mitochondria-associated programmed cell death as a therapeutic target for age-related disease

Nguyen Thanh T.,Wei Shibo,Nguyen Thu Ha,Jo Yunju,Zhang Yan,Park Wonyoung,Gariani Karim,Oh Chang-Myung,Kim Hyeon Ho,Ha Ki-Tae,Park Kyu-Sang,Park Raekil,Lee In-Kyu,Shong Minho,Houtkooper Riekelt H.,Ryu 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Mitochondria, ubiquitous double-membrane-bound organelles, regulate energy production, support cellular activities, harbor metabolic pathways, and, paradoxically, mediate cell fate. Evidence has shown mitochondria as points of convergence for diverse cell death-inducing pathways that trigger the various mechanisms underlying apoptotic and nonapoptotic programmed cell death. Thus, dysfunctional cellular pathways eventually lead or contribute to various age-related diseases, such as neurodegenerative, cardiovascular and metabolic diseases. Thus, mitochondrion-associated programmed cell death-based treatments show great therapeutic potential, providing novel insights in clinical trials. This review discusses mitochondrial quality control networks with activity triggered by stimuli and that maintain cellular homeostasis via mitohormesis, the mitochondrial unfolded protein response, and mitophagy. The review also presents details on various forms of mitochondria-associated programmed cell death, including apoptosis, necroptosis, ferroptosis, pyroptosis, parthanatos, and paraptosis, and highlights their involvement in age-related disease pathogenesis, collectively suggesting therapeutic directions for further research.

Magnetic and magnetocaloric properties of Ni-Ag-Mn-Sn ribbons and their composites

Thanh, Tran Dang,Duc, Nguyen Huu,Dan, Nguyen Huy,Mai, N.T.,Phan, T.L.,Oh, S.K.,Yu, Seong-Cho Elsevier 2017 Journal of Alloys and Compounds Vol.696 No.-

<P><B>Abstract</B></P> <P>In this work, we have investigated the influence of Ag-doping on the magnetic and magnetocaloric effect (MCE) of Ni<SUB>50-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons with <I>x</I> = 1, 2, and 4, which were prepared by a melt-spinning method. With increasing Ag concentration, a systematic decrease in the antiferromagnetic interaction and in the magnetic phase transition temperatures was observed. Analyses of the critical behavior based on the Banerjee criterion and scaling hypothesis for <I>M</I>(<I>H</I>, <I>T</I>) data near the ferromagnetic-paramagnetic transformation prove an increase of Ag favors establishing long-range ferromagnetic interactions in the austenitic phase. The temperature and magnetic field dependences of magnetic entropy change, Δ<I>S</I> <SUB>m</SUB>(<I>T</I>, <I>H</I>) were investigated via isothermal magnetization measurements. Interestingly, these samples exhibit a MCE at room-temperature with the Δ<I>S</I> <SUB>m</SUB>(<I>T</I>) curves distributed over a quite wide temperature range. To enhance the relative cooling power (RCP) value and to extend the magnetic phase transition region, we have prepared the composites in the form of the layered material samples based on ribbons obtained above. Under Δ<I>H</I> = 10 kOe, the maximum value of Δ<I>S</I> <SUB>m</SUB> (denoted as |Δ<I>S</I> <SUB>max</SUB>|) at around room-temperature is 1.08 J kg<SUP>−1</SUP> K<SUP>−1</SUP>, corresponding to RCP = 51.8 J kg<SUP>−1</SUP>, which is about 10% higher than that obtained from a separate sample. Additionally, we also pointed out that the dependences of |Δ<I>S</I> <SUB>max</SUB>| on Δ<I>H</I> at around room-temperature for samples obey a power law, |Δ<I>S</I> <SUB>max</SUB>| = <I>a</I> × Δ<I>H</I> <SUP>n</SUP>, and all the Δ<I>S</I> <SUB>m</SUB>(<I>T</I>, <I>H</I>) data obey completely a universal master curve.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An increase of Ag in Ni<SUB>1-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons favors establishing long-range FM order in the austenitic phase. </LI> <LI> High magnetic entropy change, wide operative temperature range, and high RCP value around room-temperature. </LI> <LI> The composite of Ni<SUB>1-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons exhibits higher RCP value and extends the magnetic phase transition region. </LI> <LI> Field dependence of |Δ<I>S</I> <SUB>max</SUB>| can be expressed by the power law. </LI> <LI> All the Δ<I>S</I> <SUB>m</SUB>(<I>T, H</I>) data around room temperature are followed a universal master curve. </LI> </UL> </P>

Reduced Graphene Oxide Field-effect Transistor as a Transducer for Ion Sensing Application

T. N. T. Nguyen,Nguyen Thanh Tien,Tran Quang Trung,N.-E. Lee 한국진공학회 2012 한국진공학회 학술발표회초록집 Vol.2012 No.2