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.

Two-stage partial melting and contrasting cooling history within the Higher Himalayan Crystalline Sequence in the far-eastern Nepal Himalaya

Imayama, T.,Takeshita, T.,Yi, K.,Cho, D.L.,Kitajima, K.,Tsutsumi, Y.,Kayama, M.,Nishido, H.,Okumura, T.,Yagi, K.,Itaya, T.,Sano, Y. Universitetsforlaget ; Elsevier Science Ltd 2012 Lithos Vol.134 No.-

The timing of partial melting and the pressure-temperature (P-T) paths in the High Himalayan Crystalline Sequence (HHCS) in far-eastern Nepal has been investigated using zircon chronology, rare earth element (REE) compositions, and P-T pseudosection analysis. Zircon from migmatites formed during Himalayan thermal events displays inherited magmatic core overgrown by two generations of metamorphic rims. The new rims are distinguished on the basis of their Tertiary ages, low MREE contents, and low Th/U ratios. The inner zircon rims from Sil+Grt+Bt+Kfs+Pl+Qtz and Ky+Sil+Grt+Bt+Ms+Pl+Qtz migmatites at different structural level of the HHCS display ages of c. 33-28Ma (Early Oligocene) and c. 21-18Ma (Early Miocene): these rims are characterized by flat MREE to HREE patterns and were overgrown by partial melt through muscovite dehydration melting under the stability of garnet, which occurred at P=c. 7-10kbar and T=c. 730-780<SUP>o</SUP>C, and at P=c. 8-14kbar and T=c. 720-770<SUP>o</SUP>C, respectively. The outer zircon rims are relatively enriched in HREE with respect to the inner rims and were overgrown at c. 27-23Ma (Late Oligocene) and at c. 18-16Ma (Early Miocene) during melt crystallization accompanying breakdown of garnet at P=c. 4-7kbar and T=c. 650-725<SUP>o</SUP>C. Early Miocene Ms-Bt leucogranites with two successively overgrown zircon rims at c. 18.3+/-0.3Ma and c. 16.3+/-0.2Ma were intruded into Early Oligocene migmatite hosts. Microstructural observations and the corresponding P-T conditions associated with the two generations of zircon rims indicate that the Early Oligocene and Early Miocene migmatites show relatively isobaric and nearly isothermal P-T paths during exhumation, respectively. The inferences are consistent with higher average cooling rates for the Early Miocene (c. 30-40<SUP>o</SUP>C/My) than the Early Oligocene (c. 15-25<SUP>o</SUP>C/My) migmatites, inferred from peak-T conditions and FT (c. 6Ma for both migmatites) and U-Pb zircon ages. The P-T-t paths of the two migmatites indicate that burial of the Early Miocene migmatites has been coeval with exhumation of the Early Oligocene migmatites, implying the formation of large-scale thrust within the HHCS.

Cellulomonas chitinilytica sp. nov., a chitinolytic bacterium isolated from cattle-farm compost

Yoon, M.-H.,Ten, L. N.,Im, W.-T.,Lee, S.-T. Microbiology Society 2008 International journal of systematic and evolutiona Vol.58 No.8

<P>A bacterial strain, designated X.bu-b T, with chitin-, xylan-, cellulose- and starch-degrading activities, was isolated from compost at a cattle farm near Daejeon, Republic of Korea. The strain comprised Gram-positive, aerobic or facultatively anaerobic, non-motile, rod-shaped bacteria. On the basis of an analysis of 16S rRNA gene sequences, the phylogenetic position of X.bu-b T was within the genus Cellulomonas, and the strain exhibited relatively high sequence similarities with respect to Cellulomonas biazotea DSM 20112T (98.1 %), C. cellasea DSM 20118T (98.1 %), C. fimi DSM 20113T (98.0 %), C. terrae DB5T (97.9 %), C. humilata ATCC 25174T (97.7 %), C. xylanilytica XIL11 T (97.5 %), C. uda DSM 20107T (97.4 %), C. gelida DSM 20111 T (97.3 %), C. iranensis OT (97.3 %) and C. flavigena DSM 20109T (97.0 %). The phylogenetic distance from other Cellulomonas species with validly published names was greater than 3 % (i.e. less than 97.0 % sequence similarity). Chemotaxonomic data also supported the classification of strain X.bu-b T within the genus Cellulomonas: L-ornithine was the cell-wall diamino acid, anteiso-C15:0 and anteiso-C17:0 were the major fatty acids, rhamnose, galactose, xylose and ribose were the cell-wall sugars, MK-9(H4) was the predominant menaquinone and diphosphatidylglycerol and phosphatidylglycerol were present in the polar lipids. The G+C content of the genomic DNA was 73.6 mol%. DNA-DNA hybridization experiments showed that the values for DNA-DNA relatedness between strain X.bu-b T and the phylogenetically closest neighbours were below 23 %. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain X.bu-b T represents a novel species of the genus Cellulomonas, for which the name Cellulomonas chitinilytica sp. nov. is proposed. The type strain is X.bu-b T (=KCTC 19133T =DSM 17922T).</P>

Electrical and Magnetotransport Properties of <inline-formula> <tex-math notation='TeX'> <tex> ${\rm La}_{{0.7}}{\rm Ca}_{{0.3}}{\rm Mn}_{{1-x}}{\rm Co}_{{x}}{\rm O}_{3}$ </tex> </tex-math></inline-formula>

Tran Dang Thanh,Phan, T. L.,Phung Quoc Thanh,Hoang Nam Nhat,Duong Anh Tuan,Yu, S. C. IEEE 2014 IEEE transactions on magnetics Vol.50 No.6

<P>This paper presents a detailed study on the Co-doping influence on the electrical and magnetotransport properties of La0.7Ca0.3Mn1-xCoxO3(x = 0.09-0.17) prepared by solid-state reaction. Magnetic measurements versus temperature revealed a gradual decrease of the magnetization (M) and Curie temperature (T-C) with increasing Co concentration (x). The T-C values vary from 194 to 159 K as changing x from 0.09 to 0.17, respectively. H/M versus M-2 performances around T-C prove the x = 0.09 sample undergoing a first-order magnetic phase transition (FOMT) while the samples with x >= 0.11 undergo a second-order magnetic phase transition (SOMT). The other with x = 0.10 is considered as a threshold concentration of the FOMT-SOMT transformation. Considering temperature dependences of resistivity, rho(T), in the presence and absence of the magnetic field, the samples (excepting for x = 0.17) exhibit a metal-insulator transition at T (P) = 60-160 K, which shifts toward lower temperatures with increasing x. In the metallic-ferromagnetic region, the rho(T) data are well fitted to a power function rho(T) = rho(0) + rho(2) T-2 + rho(4.5) T-4.5. This indicates electron-electron and electron-magnon scattering processes are dominant at temperatures T < T (P). In addition, the conduction data at temperatures T > theta(D)/2 (theta(D) is the Debye temperature) and T (P) < T < theta(D)/2 obey the small-polaron and variable-range hopping models, respectively. The values of activation energy E-p, and density of states at the Fermi level N(E-F) were accordingly determined. Here, N(E-F) increases while E-p decreases when an external magnetic field is applied. We also have found that N(E-F) increases when materials transfer from the FOMT to the SOMT, and N(E-F) value becomes smallest for the sample having the coexistence of the FOMT and SOMT (i.e., x = 0.10).</P>

Seroprevalence of Toxoplasma gondii and Trichinella spiralis infections in wild boars (Sus scrofa) in Korea

Kang, S.W.,Doan, H.T.T.,Noh, J.H.,Choe, S.E.,Yoo, M.S.,Kim, Y.H.,Reddy, K.E.,Nguyen, T.T.D.,Van Quyen, D.,Nguyen, L.T.K.,Kweon, C.H.,Jung, S.C. Elsevier 2013 Parasitology international Vol.62 No.6

Toxoplasma gondii and Trichinella spiralis are important zoonotic pathogens with worldwide distributions. In Korea, several outbreaks of human toxoplasmosis and trichinellosis due to the consumption of infected wild animals have been reported. The purpose of this study was to determine the seroprevalence of T. gondii and T. spiralis infections in wild boars killed in Korea from December 2009 to October 2011. A total of 521 wild boars hunted in eight provinces were examined for antibodies to T. gondii and T. spiralis by using commercial ELISA kits. Overall, 25.1% of serum samples from individual boars were seropositive for T. gondii and 1.7% were seropositive for T. spiralis. Seropositive for T. gondii was found in the boars in all the eight provinces investigated and for T. spiralis in four provinces. This is the first report on the seroprevalence of T. gondii and T. spiralis infections in wild boars in Korea. The consumption of undercooked wild boar meat may expose humans to a high risk of infection.

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>

STAR FORMATION LAWS IN BOTH GALACTIC MASSIVE CLUMPS AND EXTERNAL GALAXIES: EXTENSIVE STUDY WITH DUST CONINUUM, HCN (4-3), AND CS (7-6)

Liu, Tie,Kim, Kee-Tae,Yoo, Hyunju,Liu, Sheng-yuan,Tatematsu, Ken’ichi,Qin, Sheng-Li,Zhang, Qizhou,Wu, Yuefang,Wang, Ke,Goldsmith, Paul F.,Juvela, Mika,Lee, Jeong-Eun,Tó,th, L. Viktor,Mardones, D American Astronomical Society 2016 The Astrophysical journal Vol.829 No.2

<P>We observed 146 Galactic clumps in HCN (4-3) and CS (7-6) with the Atacama Submillimeter Telescope Experiment 10 m telescope. A tight linear relationship between star formation rate and gas mass traced by dust continuum emission was found for both Galactic clumps and the high redshift (z > 1) star forming galaxies (SFGs), indicating a constant gas depletion time of similar to 100 Myr for molecular gas in both Galactic clumps and high z SFGs. However, low z galaxies do not follow this relation and seem to have a longer global gas depletion time. The correlations between total infrared luminosities (L-TIR) and molecular line luminosities (L-mol') of HCN (4-3) and CS (7-6) are tight and sublinear extending down to clumps with L-TIR similar to 10(3) L-circle dot. These correlations become linear when extended to external galaxies. A bimodal behavior in the L-TIR-L-mol' correlations was found for clumps with different dust temperature, luminosity-to-mass ratio, and sigma(line)/sigma(vir). Such bimodal behavior may be due to evolutionary effects. The slopes of L-TIR-L-mol' correlations become more shallow as clumps evolve. We compared our results with lower J transition lines in Wu et al. (2010). The correlations between clump masses and line luminosities are close to linear for low effective excitation density tracers but become sublinear for high effective excitation density tracers for clumps with L-TIR larger than L-TIR similar to 10(4.5) L-circle dot. High effective excitation density tracers cannot linearly trace the total clump masses, leading to a sublinear correlations for both M-clump-L-mol' and L-TIR-L-mol' relations.</P>

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>

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.