Influence of Cr Doping on the Critical Behavior of Amorphous Alloy Ribbons Fe_{78–<i>x</i>}Cr_<i>x</i>Si₄Nb₅B₁₂Cu₁

Phan, T. L.,Thanh, P. Q.,Chau, N.,Huu, C. X.,Ngo, D.-T,Ho, T. A.,Thanh, T. D.,Yu, S. C. IEEE 2014 IEEE transactions on magnetics Vol.50 No.11

<P>Though many previous works focused on studying Cr-doped Fe-Si-Nb-B-Cu amorphous alloys, magnetic-interaction mechanisms in these materials have not been carefully investigated yet. Dealing with these issues, we have prepared the amorphous alloy ribbons Fe<SUB>78-x</SUB>Cr<SUB>x</SUB>Si<SUB>4</SUB>Nb<SUB>5</SUB>B<SUB>12</SUB>Cu<SUB>1</SUB> with x= 1, 3, and 6, and then studied their magnetic and critical properties. Magnetization versus temperature and magnetic-field measurements, MHT, performed on a vibrating sample magnetometer reveal that the Cr-content increase in Fe<SUB>78-x</SUB>Cr<SUB>x</SUB>Si<SUB>4</SUB>Nb<SUB>5</SUB>B<SUB>12</SUB>Cu<SUB>1</SUB> reduces the T<SUB>C</SUB> from 430 K for x= 1 to about 322 K (for x= 6). This indicates the decline of ferromagnetic (FM) exchange interactions between Fe atoms when there is the presence of Cr atoms. We have also analyzed the M(H) data at the temperatures in the vicinity of the T<SUB>C</SUB> using the modified Arrott plot method and the scaling hypothesis, and determined the values of the critical exponents β = 0.367-0.376 and γ = 1.315-1.338. These values are close to those expected for the 3-D Heisenberg model with β = 0.365 and γ = 1.336, proving the existence of short-range FM order in the amorphous alloy ribbons.</P>

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>

FOXO protects against age‐progressive axonal degeneration

Hwang, Inah,Oh, Hwanhee,Santo, Evan,Kim, Do&#x2010,Yeon,Chen, John W.,Bronson, Roderick T.,Locasale, Jason W.,Na, Yoonmi,Lee, Jaclyn,Reed, Stewart,Toth, Miklos,Yu, Wai H.,Muller, Florian L.,Paik, Jihy John Wiley and Sons Inc. 2018 AGING CELL Vol.17 No.1

<P><B>Summary</B></P><P>Neurodegeneration resulting in cognitive and motor impairment is an inevitable consequence of aging. Little is known about the genetic regulation of this process despite its overriding importance in normal aging. Here, we identify the Forkhead Box O (FOXO) transcription factor 1, 3, and 4 isoforms as a guardian of neuronal integrity by inhibiting age‐progressive axonal degeneration in mammals. FOXO expression progressively increased in aging human and mouse brains. The nervous system‐specific deletion of <I>Foxo</I> transcription factors in mice accelerates aging‐related axonal tract degeneration, which is followed by motor dysfunction. This accelerated neurodegeneration is accompanied by levels of white matter astrogliosis and microgliosis in middle‐aged <I>Foxo</I> knockout mice that are typically only observed in very old wild‐type mice and other aged mammals, including humans. Mechanistically, axonal degeneration in nerve‐specific <I>Foxo</I> knockout mice is associated with elevated mTORC1 activity and accompanying proteotoxic stress due to decreased Sestrin3 expression. Inhibition of mTORC1 by rapamycin treatment mimics FOXO action and prevented axonal degeneration in <I>Foxo</I> knockout mice with accelerated nervous system aging. Defining this central role for FOXO in neuroprotection during mammalian aging offers an invaluable window into the aging process itself.</P>

Heat Treatment Influence on Tribological Properties of AlCoCrCuFeNi High‑Entropy Alloy in Hydrogen Peroxide‑Solution

X. S. Luo,J. Li,Y. L. Jin,C. P. Hu,D. Jia,S. P. Zhan,Y. Yu,M. Hua,H. T. Duan 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.8

Tribological properties of AlCoCrCuFeNi high-entropy alloy were studied after annealing at various temperatures. X-raydiffraction, scanning electron microscopy, energy dispersive spectroscopy, microhardness tester and pin-on-disc tribometeranalyses were performed to reveal the microstructure, composition, microhardness and tribological behavior variations. Withthe heat treatment temperature increasing, time taken for friction coefficient going through the rapidly dropping down andthen into the stable period increases, the white sheets structures and their size in dendrite area of the AlCoCrCuFeNi alloybecomes bigger, however BCC content declined dramatically. Then, the average friction coefficient of the AlCoCrCuFeNi/Si3N4 sliding friction pair increase from 0.037 to 0.115, and the pin wear loss increase from 3 to 11 μm.

Evaluation of sintering behavior of ash particles from coal and rice straw using optical heating stage microscope at high temperature fouling conditions

Namkung, H.,Hu, X.,Kim, H.T.,Wang, F.,Yu, G. Elsevier Scientific Pub. Co 2016 Fuel processing technology Vol.149 No.-

Ash adhesion and elimination in the gasification process is one of the main challenges in maintaining a continuous operation of the plant. The properties of ash adhesion and elimination are mainly related to particle sintering behavior. Different sintering behaviors of Shenhua coal ash (SCA) and rice straw ash (RSA) below the inherent initial deformation temperature (IDT) were observed by using optical heating stage microscope (OHSM) under CO<SUB>2</SUB> and Ar environments. The particle interaction of the RSA, the IDT of which was lower than that of SCA, was higher than that of SCA at the same temperature. Adding RSA to the SCA was an effective means of increasing particle sintering of SCA. The sintering reaction rate of ash particles highly increased at beginning of sintering stage. The effects of inorganic chemicals in the sintering process were evaluated by using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and typical fouling indices. The Ca and K were predominant contributors to the increase in sintering. The degree of sintering through the experiments was compared to a modified Frenkel sintering model, which accurately simulated the sintering tendency under isothermal conditions.

Paricalcitol attenuates lipopolysaccharide-induced myocardial inflammation by regulating the NF-κB signaling pathway

LEE, AE SIN,JUNG, YU JIN,THANH, TÙ,NG NGUY&#x1ec4,N,LEE, SIK,KIM, WON,KANG, KYUNG PYO,PARK, SUNG KWANG UNKNOWN 2016 INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE Vol.37 No.4

<P>Vitamin D deficiency is associated with an increased risk of cardiovascular disease, diabetes, colon and breast cancer, infectious diseases and allergies. Vascular alterations are an important pathophysiological mechanism of sepsis. Experimental data suggest that paricalcitol, a vitamin D2 analogue, exerts beneficial effects on renal inflammation and fibrosis. In the present study, we aimed to investigate the effects of paricalcitol on lipopolysaccharide (LPS)-induced myocardial inflammation and to elucidate the underlying mechanisms. We used primary cultured human umbilical vein endothelial cells for <I>in vitro</I> experiments, in which stimulation with tumor necrosis factor (TNF)-α was used to induce endothelial cell inflammation. For <I>in vivo</I> experiments, myocardial inflammation was induced by an intraperitoneal injection of 15 mg/kg LPS into C57BL6 mice pre-treated with or without 0.2 <I>µ</I>g/kg paricalcitol. Treatment with paricalcitol suppressed the TNF-α-induced increase in the protein expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and fractalkine in endothelial cells. Treatment with paricalcitol also decreased the TNF-α-induced nuclear factor (NF)-κB binding activity. In a mouse model of LPS-induced myocardial inflammation, pre-treatment with paricalcitol prevented the LPS-induced increase in the expression of myocardial ICAM-1, phosphorylated p65 and myocardial TNF-α. Pre-treatment with paricalcitol also alleviated endotoxemia-induced microvascular leakage in the myocardium. The findings of our study suggest that paricalcitol exerts a protective effect against LPS-induced myocardial inflammation by regulating the expression of cell adhesion molecules and TNF-α, and by improving myocardial permeability.</P>

γ-Glutamyl transpeptidase (GgtA) of Aspergillus nidulans is not necessary for bulk degradation of glutathione

Spitzmü,ller, Zsolt,Kwon, Nak-Jung,Szilá,gyi, Melinda,Keser&#x171,, Judit,Tó,th, Viktó,ria,Yu, Jae-Hyuk,Pó,csi, Istvá,n,Emri, Tamá,s Springer-Verlag 2015 Archives of microbiology Vol.197 No.2

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>

Exchange coupling in ferromagnetic/antiferromagnetic/ferromagnetic [Pd/Co]_<i>n</i>/NiO/Co trilayers with different [Pd/Co] anisotropy

Yu, T.,Ning, X.K.,Liu, W.,Feng, J.N.,Kim, D.,Choi, C.J.,Zhang, Z.D. Elsevier 2015 Journal of magnetism and magnetic materials Vol.385 No.-

<P><B>Abstract</B></P> <P>Exchange coupling in NiO/Co bilayers and [Pd/Co(<I>t</I> <SUB> <I>Co</I> </SUB>)]<SUB> <I>n</I> </SUB>/NiO/Co trilayers prepared by magnetron sputtering has been investigated. With decreasing thickness (<I>t</I> <SUB> <I>Co</I> </SUB>) of the Co layers in [Pd/Co] multilayers (MLs) and increasing number of [Pd/Co] repeats (<I>n</I>), the ferromagnetic easy axis of the [Pd/Co] MLs switches from in-plane to out-of-plane direction. Ferromagnetic and non-collinear interlayer couplings between the [Pd/Co] MLs and the Co layer across the antiferromagnetic NiO spacer are found in trilayers. After cooling at in-plane and out-of-plane remanent state, respectively, for <I>t</I> <SUB> <I>Co</I> </SUB>=1nm and <I>n</I>=2, a larger in-plane exchange bias field of 724Oe is observed which vanishes at temperatures above 90K which is the same as the in-plane blocking temperature observed in the NiO/Co bilayer. For <I>t</I> <SUB> <I>Co</I> </SUB>=0.3nm and <I>n</I>=7, the in-plane blocking temperature in the trilayer enhances up to 210K, which strongly depends on orientation and strength of the ferromagnetic [Pd/Co] ML anisotropy axis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The easy axis of the [Pd/Co] MLs switches from in-plane to out-of-plane direction. </LI> <LI> Ferromagnetic and non-collinear interlayer couplings are found in the trilayers. </LI> <LI> A larger in-plane <I>H</I> <SUB> <I>E</I> </SUB> of 724Oe is observed for the trilayers <I>t</I> <SUB> <I>Co</I> </SUB>=1nm and <I>n</I>=2. </LI> <LI> The in-plane blocking temperature <I>T</I> <SUB> <I>B</I> </SUB> increases up to 210K for <I>t</I> <SUB> <I>Co</I> </SUB>=0.3nm and <I>n</I>=7. </LI> </UL> </P>

Critical behavior of Y-doped Nd_0.7Sr_0.3MnO₃ manganites exhibiting the tricritical point and large magnetocaloric effect

Phan, The-Long,Ho, T.A.,Thang, P.D.,Tran, Q.T.,Thanh, T.D.,Phuc, N.X.,Phan, M.H.,Huy, B.T.,Yu, S.C. Elsevier 2014 JOURNAL OF ALLOYS AND COMPOUNDS Vol.615 No.-

<P><B>Abstract</B></P> <P>We have determined the values of critical exponents of two polycrystalline samples (Nd<SUB>1−</SUB> <I> <SUB>x</SUB> </I>Y<I> <SUB>x</SUB> </I>)<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB> (<I>x </I>=0 and 0.07) from the magnetization data versus temperature and magnetic field, <I>M</I>(<I>H</I>, <I>T</I>), to learn about their magnetic and magnetocaloric (MC) properties. The results reveal the samples exhibiting the crossover of first-order and second-order phase transitions, where the exponent values <I>β </I>=0.271 and <I>γ </I>=0.922 for <I>x </I>=0, and <I>β </I>=0.234–0.236 and <I>γ </I>=1.044–1.063 for <I>x </I>=0.07 determined by using modified Arrott plots and static-scaling hypothesis are close to those expected for the tricritical mean-field theory (<I>β </I>=0.25 and <I>γ </I>=1.0). Particularly, the <I>T</I> <SUB>C</SUB> of <I>x </I>=0 and 0.07 can be any value in the temperature ranges of 240–255K and 170–278K, respectively, depending on the magnitude of applied magnetic field and determination techniques. Around the <I>T</I> <SUB>C</SUB>, studying the MC effect of the samples has revealed a large magnetic-entropy change (Δ<I>S</I> <SUB>m</SUB>) up to ∼8J/kgK for the applied field interval Δ<I>H </I>=50kOe, corresponding to refrigerant capacity values of 200–245J/kg. These phenomena are related to the crossover nature and the persisting of FM/anti-FM interactions even above the <I>T</I> <SUB>C</SUB>, as further confirmed by electron-spin-resonance data, Curie–Weiss law-based analyses, and an exponential parameter characteristic of magnetic order <I>n </I>=dLn|Δ<I>S</I> <SUB>m</SUB>|/dLn<I>H</I>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Tricritical point in Y-doped Nd<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB> manganites. </LI> <LI> A large magnetic-entropy change. </LI> <LI> Magnetic inhomogeneity and phase separation. </LI> </UL> </P>