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>

Conventional and inverse magnetocaloric effects, and critical behaviors in Ni₄₃Mn₄₆Sn₈In₃ alloy

Thanh, T.D.,Nan, W.Z.,Nam, G.,Van, H.T.,You, T.S.,Phan, T.L.,Yu, S.C. Elsevier 2015 CURRENT APPLIED PHYSICS Vol.15 No.10

A systematic study of the conventional and inverse magnetocaloric effects, and critical behaviors in an alloy ingot of Ni<SUB>43</SUB>Mn<SUB>46</SUB>Sn<SUB>8</SUB>In<SUB>3</SUB> has been performed. Our results reveal the sample exhibiting structural and magnetic phase transitions at temperatures T<SUB>C</SUB><SUP>M</SUP> = 166 K (T<SUB>C</SUB> of the martensitic phase), T<SUB>M-A</SUB> = 260 K (the martensitic-to-austenitic phase transformation) and T<SUB>C</SUB><SUP>A</SUP> = 296 K (T<SUB>C</SUB> of the austenitic phase). The large values of refrigerant capacity (RC) around T<SUB>M-A</SUB> and T<SUB>C</SUB><SUP>A</SUP> are found to be RC<SUB>M-A</SUB> = 172.6 and RC<SUB>A</SUB> = 155.9 J kg<SUP>-1</SUP>, respectively, under an applied field change of 30 kOe. Our critical analyses near the T<SUB>C</SUB><SUP>M</SUP> and T<SUB>C</SUB><SUP>A</SUP> reveal that a coexistence of the long- and short-range ferromagnetic order in the martensitic phase, while the long-range ferromagnetic order exists in the austenitic phase. Interestingly, at around T<SUB>C</SUB><SUP>A</SUP>, the maximum magnetic entropy change (|ΔS<SUB>max</SUB>|) versus magnetic field H obeys a power law, |ΔS<SUB>max</SUB>| = a.H<SUP>n</SUP>, where the exponent n is found to be about 0.66.

Unusual Critical Behavior in La_1.2Sr_1.8Mn₂O₇ Single Crystal

Thanh, Tran Dang,Xuan Hau, Kieu,Huyen Yen, Pham Duc,Manh, T. V.,Yu, S. C.,Phan, T. L.,Telegin, A.,Telegin, S.,Naumov, S. IEEE 2018 IEEE transactions on magnetics Vol.54 No.11

<P>In this paper, we present a detailed analysis on the critical behavior of La<SUB>1.2</SUB>Sr<SUB>1.8</SUB>Mn<SUB>2</SUB>O<SUB>7</SUB> single crystal via isothermal magnetization measured at different temperatures around the paramagnetic–ferromagnetic phase transition at <TEX>$T_{C} = 85$</TEX> K. Using the Landau–Lifshitz coefficients, the Arrott plots ( <TEX>$H/M = a(T) + b(T)M^{2}$</TEX>) of sample have been analyzed. It showed that a(T) changed from positive to negative values at different temperatures in the field ranges of <TEX>$H = 0$</TEX>–10, 10–30, and 30–50 kOe, indicating that the critical behavior could not be described with a single model under different applied fields. Through the modified Arrott plots method, the Kouvel–Fisher method, and the critical isotherm analysis, we determined the values of the critical exponents for La<SUB>1.2</SUB>Sr<SUB>1.8</SUB>Mn<SUB>2</SUB>O<SUB>7</SUB> around its magnetic phase transition over different magnetic field ranges. The critical exponent <TEX>$\beta $</TEX> value is found to be 0.501, 0.417, and 0.371 under field ranges of <TEX>$H = 0$</TEX>–10, 10–30, and 30–50 kOe, respectively. This means that the <TEX>$\beta $</TEX> value depends strongly on the strength of the applied field, shifting from the value approaching that of the mean field model ( <TEX>$\beta = 0.5$</TEX>) to the 3-D-Heisenbeg model ( <TEX>$\beta = 0.365$</TEX>). Meanwhile, its <TEX>$\gamma $</TEX> value is quite stable ( <TEX>$\gamma =0.973$</TEX>–1.074), almost independent on the choice of field fitting range. In addition, using the reduced temperature <TEX>$\varepsilon = (T-T_{C}$</TEX>)/ <TEX>$T_{C}$</TEX> and the obtained critical exponents, almost <TEX>$M(H, T$</TEX>) data measured near <TEX>$T_{C}$</TEX> obey the scaling equation <TEX>$M(H, \varepsilon) = \varepsilon ^{\boldsymbol {\beta }}f_{\pm }(H/\varepsilon ^{\boldsymbol {\beta +\gamma }}$</TEX>), where <TEX>$f_{+}$</TEX> and <TEX>$f_{-}$</TEX> are regular analytic functions corresponding to data at <TEX>$T > T_{C}$</TEX> and <TEX>$T < T_{C}$</TEX>, respectively.</P>

Magnetic and magnetocaloric properties in La_0.7Ca_0.3-xNa_xMnO₃ exhibiting first-order and second-order magnetic phase transitions

Ho, T.A.,Dang, N.T.,Phan, T.L.,Yang, D.S.,Lee, B.W.,Yu, S.C. Elsevier Sequoia 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.676 No.-

Polycrystalline orthorhombic samples La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Na<SUB>x</SUB>MnO<SUB>3</SUB> (x = 0-0.09) were prepared by solid-state reaction. The study of magnetic properties revealed that the ferromagnetic-paramagnetic (FM-PM) transition temperature (T<SUB>C</SUB>) increases from 255 to about 271 K with increasing Na-doping content (x) from 0 to 0.09, respectively. Around the T<SUB>C</SUB>, we have found the samples showing a large magnetocaloric (MC) effect with maximum values of magnetic entropy change (|ΔS<SUB>max</SUB>|) of 7-8 J kg<SUP>-1</SUP> K<SUP>-1</SUP> and relative cooling power RCP = 232-236 J/kg for the samples x = 0.03-0.09 in a magnetic-field interval ΔH = 40 kOe. Detailed analyses of isothermal magnetization data M(T, H) based on Banerjee's criteria indicated a first-to-second-order magnetic-phase transformation taking place at a threshold Na-doping concentration x<SUB>c</SUB> ~ 0.06. This could also be observed clearly from the feature of entropy universal curves. An assessment of the magnetic-ordering exponent N = dLn|ΔS<SUB>m</SUB>|/dLnH demonstrates an existence of short-range magnetic order in the samples. We believe that the changes of the magnetic properties and MC effect in La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Na<SUB>x</SUB>MnO<SUB>3</SUB> caused by Na doping are related to the changes in the structural parameters and Mn<SUP>4+</SUP>/Mn<SUP>3+</SUP> ratio, which are confirmed by the geometrical and electronic analyses based on X-ray diffraction and X-ray absorption fine structure.

First-to-second-order magnetic-phase transformation in La_0.7Ca_0.3-xBa_xMnO₃ exhibiting large magnetocaloric effect

Phan, T.L.,Dang, N.T.,Ho, T.A.,Manh, T.V.,Thanh, T.D.,Jung, C.U.,Lee, B.W.,Le, A.T.,Phan, A.D.,Yu, S.C. Elsevier Sequoia 2016 Journal of alloys and compounds Vol.657 No.-

We have prepared polycrystalline samples La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Ba<SUB>x</SUB>MnO<SUB>3</SUB> (x = 0, 0.025, 0.05, 0.075 and 0.1) by solid-state reaction, and then studied their magnetic properties and magnetocaloric (MC) effect based on magnetization versus temperature and magnetic-field (M-H-T) measurements. Experimental results reveal the easiness in tuning the Curie temperature (T<SUB>C</SUB>) from 260 to about 300 K by increasing Ba-doping concentration (x) from 0 to 0.1. Under an applied field H = 50 kOe, maximum magnetic-entropy changes around T<SUB>C</SUB> of the samples can be tuned in the range between 6 and 11 J kg<SUP>-1</SUP> K<SUP>-1</SUP>, corresponding to refrigerant-capacity values ranging from 190 to 250 J kg<SUP>-1</SUP>. These values are comparable to those of some conventional MC materials, and reveal the applicability of La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Ba<SUB>x</SUB>MnO<SUB>3</SUB> materials in magnetic refrigeration. Analyses of the critical behavior based on the Banerjee criteria, Arrott plots and scaling hypothesis for M-H-T data prove a magnetic-phase separation when Ba-doping concentration changes. In the doping region x = 0.05-0.075, the samples exhibits the crossover of first- and second-order phase transitions with the values of critical exponents β and γ close to those expected for the tricritical mean-field theory. The samples with x < 0.05 and x > 0.075 exhibit first- and second-order transitions, respectively. More detailed analyses related to the Griffiths singularity, the critical behavior for different magnetic-field intervals started from 10 kOe, and the magnetic-ordering parameter n = dLn|ΔS<SUB>m</SUB>|/dLnH (where ΔS<SUB>m</SUB> is the magnetic-entropy change) demonstrate magnetic inhomogeneities and multicritical phenomena existing in the samples.

Levels of 4-1BB transcripts and soluble 4-1BB protein are elevated in the adipose tissue of human obese subjects and are associated with inflammatory and metabolic parameters

Tu, T H,Kim, C-S,Kang, J-H,Nam-Goong, I S,Nam, C W,Kim, E S,Kim, Y I,Choi, J I,Kawada, T,Goto, T,Park, T,Yoon Park, J H,Choi, M-S,Yu, R Macmillan Publishers Limited 2014 International journal of obesity Vol.38 No.8

Background:4-1BB, a member of the TNF receptor superfamily, has a role in various inflammatory pathologies through its interaction with 4-1BB ligand. We previously demonstrated that it participates in initiating and promoting obesity-induced adipose inflammation in a rodent model.Objective:In this study, we examined whether 4-1BB is related to obesity-induced adipose inflammation and metabolic parameters in humans.Methods:A total of 50 subjects, 25 obese (body mass index (BMI)⩾25 kg m<SUP>−2</SUP>) and 25 lean (BMI<23 kg m<SUP>−2</SUP>) participated in the study. The levels of 4-1BB transcripts and soluble 4-1BB protein (s4-1BB) in subcutaneous adipose tissue were measured by quantitative real-time PCR and enzyme-linked immunosorbent assay, respectively. Inflammatory and metabolic parameters were measured by enzymatic analysis and immunoassay.Results:Obese subjects had higher levels of both 4-1BB transcripts and s4-1BB protein in subcutaneous adipose tissue than lean controls, and the levels were correlated with BMI and the expression of inflammatory markers, as well as with serum metabolic parameters. Moreover, s4-1BB was released from human adipocytes, and elicited chemotactic responses from human monocytes/T cells as well as enhancing their inflammatory activity, indicating that it may promote human adipose inflammation.Discussion:Our data demonstrate that elevated levels of 4-1BB transcripts and s4-1BB in adipose tissue are closely associated with obesity-induced inflammation and metabolic dysregulation. They suggest that both 4-1BB transcripts and s4-1BB could serve as novel biomarkers and/or therapeutic targets for obesity-induced inflammation and metabolic syndrome in humans.

ESR study of La_1–xPb_xMnO₃ (0.1 ≤ x ≤ 0.5) perovskites

Phan, T. L.,Min, S. G.,Phan, M. H.,Ha, N. D.,Chau, N.,Yu, S. C. Wiley - VCH Verlag GmbH & Co. KGaA 2007 Physica status solidi. B Vol. No.

<P>Electron spin resonance (ESR) spectra of La<SUB>1–x </SUB>Pb<SUB>x </SUB>MnO<SUB>3</SUB> (0.1 ≤ x ≤ 0.5) compounds were recorded at different temperatures. Asymmetrical and distored resonance signals due to ferromagnetic correlations at temperatures T < T<SUB>min</SUB> became Lorentzian at T > T<SUB>min</SUB>, where T<SUB>min</SUB> is the temperature corresponding to the narrowest ESR linewidth. The ESR linewidth with respect to temperature, ΔH (T), for the samples was fitted to the one-phonon process, ΔH (T) = A + BT. We found that B decreased from 5.45 Oe/K for x = 0.1 to 4.61 Oe/K for x = 0.5, indicating the decrease of lattice distortions with the Pb addition. The tem- perature dependence of the ESR intensity, I (T), for the samples was described well to an expression of I (T) = I<SUB>0</SUB> exp (E<SUB>a</SUB>/k<SUB>B</SUB>T). In the high-temperature region, 1/I (T) obeyed the Curie–Weiss law. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>

Influence of Ti Doping on the Critical Behavior and Magnetocaloric Effect in Disordered Ferromagnets La0.7Ba0.3Mn1−x Ti x O3

Ho, T. A.,Phan, M. H.,Phuc, N. X.,Lam, V. D.,Phan, T. L.,Yu, S. C. Springer Science + Business Media 2016 Journal of electronic materials Vol.45 No.5

<P>The Ti-substitution influence on the magnetic and magnetocaloric properties of La0.7Ba0.3Mn1-x Ti (x) O-3 (x = 0.05 and 0.1) was investigated. Based on Banerjee's criteria and Franco's universal curves, we proved the existence of a second-order magnetic phase transition in the samples. Using the modified Arrott plot method, we determined the critical parameters T (C) a parts per thousand 245 K, beta = 0.374 +/- A 0.013, gamma = 1.228 +/- A 0.045, and delta = 4.26 +/- A 0.03 for x = 0.05, and T (C) a parts per thousand 169 K, beta = 0.339 +/- A 0.001, gamma = 1.307 +/- A 0.003, and delta = 4.78 +/- A 0.02 for x = 0.1. With these critical values, the predictable scaling behavior of the M(H) data above and below T (C) proves that the calculated exponents are unambiguous and intrinsic. The values beta = 0.374 for x = 0.05 and beta = 0.339 for x = 0.1 suggest that the magnetic phase transition of the samples falls into the three-dimensional (3D) Heisenberg and 3D Ising universality classes, respectively, corresponding to short-range ferromagnetic (FM) order due to FM clusters in a wide temperature range even above T (C), as confirmed by electron spin resonance studies. In reference to the magnetocaloric effect around T (C), the magnetic entropy change reaches maximum values (|Delta S-max|) of about 4 and 3 J kg(-1) K-1 for x = 0.05 and 0.1, respectively, for a magnetic field change 50 kOe. Magnetic field dependencies of |Delta S-max| obey a power function |Delta S-max(H)| ae H (n) , where exponent values n = 0.59 and 0.61 for x = 0.05 and 0.1, respectively, were determined from the relation n = 1 + (beta-1)/(beta + gamma). The difference between the experimental n values and the theoretical value n = 2/3 of the mean field model is due to the presence of short-range FM order in the samples.</P>

Characterization of T-DNA insertion mutants with decreased virulence in the entomopathogenic fungus Beauveria bassiana JEF-007

Kim, S.,Lee, S. J.,Nai, Y. S.,Yu, J. S.,Lee, M. R.,Yang, Y. T.,Kim, J. S. Springer International 2016 Applied Microbiology and Biotechnology Vol. No.

<P>The bean bug, Riptortus pedestris, is a major agricultural pest that reduces crop quality and value. Chemical pesticides have contributed to pest management, but resistance to these chemicals has significantly limited their use. Alternative strategies with different modes of action, such as entomopathogenic fungi, are therefore of great interest. Herein, we explored how entomopathogenic fungi can potentially be used to control the bean bug and focused on identifying virulence-related genes. Beauveria bassiana (JEF isolates) were assayed against bean bugs under laboratory conditions. One isolate, JEF-007, showed > 80 % virulence by both spray and contact exposure methods. Agrobacterium tumefaciens-mediated transformation (AtMT) of JEF-007 generated 249 random transformants, two of which (B1-06 and C1-49) showed significantly reduced virulence against Tenebrio molitor and R. pedestris immatures. Both species were used for rapid screening of virulence-reduced mutants. The two transformants had different morphologies, conidial production, and thermotolerance than the wild type. To determine the localization of the randomly inserted T-DNA, thermal asymmetric interlaced (TAIL) PCR was conducted and analysis of the two clones found multiple T-DNA insertions (two in B1-06 and three in C1-49). Genes encoding complex I intermediate-associated protein 30 (CIA30) and the autophagy protein (Atg22) were possibly disrupted by the T-DNA insertion and might be involved in the virulence. This work provides a strong platform for future functional genetic studies of bean bug-pathogenic B. bassiana. The genes putatively involved in fungal virulence should be experimentally validated by knockdown in future studies.</P>

Complete chloroplast genome sequences of Solanum commersonii and its application to chloroplast genotype in somatic hybrids with Solanum tuberosum

Cho, K. S.,Cheon, K. S.,Hong, S. Y.,Cho, J. H.,Im, J. S.,Mekapogu, M.,Yu, Y. S.,Park, T. H. Springer International 2016 Plant cell reports Vol. No.

<P>Chloroplast genome of Solanum commersonii and S olanum tuberosum were completely sequenced, and Indel markers were successfully applied to distinguish chlorotypes demonstrating the chloroplast genome was randomly distributed during protoplast fusion. Somatic hybridization has been widely employed for the introgression of resistance to several diseases from wild Solanum species to overcome sexual barriers in potato breeding. Solanum commersonii is a major resource used as a parent line in somatic hybridization to improve bacterial wilt resistance in interspecies transfer to cultivated potato (S. tuberosum). Here, we sequenced the complete chloroplast genomes of Lz3.2 (S. commersonii) and S. tuberosum (PT56), which were used to develop fusion products, then compared them with those of five members of the Solanaceae family, S. tuberosum, Capsicum annum, S. lycopersicum, S. bulbocastanum and S. nigrum and Coffea arabica as an out-group. We then developed Indel markers for application in chloroplast genotyping. The complete chloroplast genome of Lz3.2 is composed of 155,525 bp, which is larger than the PT56 genome with 155,296 bp. Gene content, order and orientation of the S. commersonii chloroplast genome were highly conserved with those of other Solanaceae species, and the phylogenetic tree revealed that S. commersonii is located within the same node of S. tuberosum. However, sequence alignment revealed nine Indels between S. commersonii and S. tuberosum in their chloroplast genomes, allowing two Indel markers to be developed. The markers could distinguish the two species and were successfully applied to chloroplast genotyping (chlorotype) in somatic hybrids and their progenies. The results obtained in this study confirmed the random distribution of the chloroplast genome during protoplast fusion and its maternal inheritance and can be applied to select proper plastid genotypes in potato breeding program.</P>