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>

Ursolic acid isolated from Uncaria rhynchophylla activates human dendritic cells via TLR2 and/or TLR4 and induces the production of IFN-γ by CD4+ naive T cells

Jung, T.Y.,Pham, T.N.N.,Umeyama, A.,Shoji, N.,Hashimoto, T.,Lee, J.J.,Takei, M. North-Holland ; Elsevier Science Ltd 2010 european journal of pharmacology Vol.643 No.2

Ursolic acid is triterpene isolated from Uncaria rhynchophylla and is a pharmacologically active substance. The induction of dendritic cell maturation is critical for the induction of Ag-specific T-lymphocyte response and may be essential for the development of human vaccine relying on T cell immunity. In this study, we investigated that the effect of Ursolic acid on the phenotypic and functional maturation of human monocyte-derived dendritic cells in vitro. Dendritic cells harvested on day 8 were examined using functional assay. The expression levels of CD1a, CD80, CD83, CD86, HLA-DR and CCR7 on Ursolic acid-primed dendritic cells was slightly enhanced. Ursolic acid dose-dependently enhanced the T cell stimulatory capacity in an allogeneic mixed lymphocyte reaction, as measured by T cell proliferation. The production of IL-12p70 induced by Ursolic acid-primed dendritic cells was inhibited by the anti-Toll-like receptor-2 (TLR2) mAb and anti-TLR4 mAb. Moreover, Ursolic acid-primed dendritic cells expressed levels of mRNA coding for both TLR2 and TLR4. The majority of cells produced considerable interferon-gamma (IFN-γ), but also small amounts of interleukin (IL-4)-4. Ursolic acid-primed dendritic cells have an intermediate migratory capacity towards CCL19 and CCL21. These results suggest that Ursolic acid modulates human dendritic cells function in a fashion that favors Th1 polarization via the activation of IL-12p70 dependent on TLR2 and/or TLR4, and may be used on dendritic cells-based vaccines for cancer immunotherapy.

Gambogic acid induces apoptotic cell death in T98G glioma cells

Thida, M.,Kim, D.W.,Tran, T.T.T.,Pham, M.Q.,Lee, H.,Kim, I.,Lee, J.W. Pergamon Press 2016 Bioorganic & medicinal chemistry letters Vol.26 No.3

Gambogic acid (GA), a natural product with a xanthone structure, has a broad range of anti-proliferative effects on cancer cell lines. We evaluated GA for its cytotoxic effects on T98G glioblastoma cells. GA exhibited potent anti-proliferative activity and induced apoptosis in T98G glioblastoma cells in a dose-dependent manner. Incubation of cells with GA revealed apoptotic features including increased Bax and AIF expression, cytochrome c release, and cleavage of caspase-3, -8, -9, and PARP, while Bcl-2 expression was downregulated. Furthermore, GA induced reactive oxygen species (ROS) generation in T98G cells. Our results indicate that GA increases Bax- and AIF-associated apoptotic signaling in glioblastoma cells.

Evogliptin, a DPP-4 inhibitor, prevents diabetic cardiomyopathy by alleviating cardiac lipotoxicity in db/db mice

Pham Trong Kha,Nguyen To Hoai T.,Yi Joo Mi,Kim Gwang Sil,Yun Hyeong Rok,Kim Hyoung Kyu,Won Jong Chul 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Dipeptidyl peptidase-4 (DPP-4) inhibitors are glucose-lowering drugs for type 2 diabetes mellitus (T2DM). We investigated whether evogliptin® (EVO), a DPP-4 inhibitor, could protect against diabetic cardiomyopathy (DCM) and the underlying mechanisms. Eight-week-old diabetic and obese db/db mice were administered EVO (100 mg/kg/day) daily by oral gavage for 12 weeks. db/db control mice and C57BLKS/J as wild-type (WT) mice received equal amounts of the vehicle. In addition to the hypoglycemic effect, we examined the improvement in cardiac contraction/relaxation ability, cardiac fibrosis, and myocardial hypertrophy by EVO treatment. To identify the mechanisms underlying the improvement in diabetic cardiomyopathy by EVO treatment, its effect on lipotoxicity and the mitochondrial damage caused by lipid droplet accumulation in the myocardium were analyzed. EVO lowered the blood glucose and HbA1c levels and improved insulin sensitivity but did not affect the body weight or blood lipid profile. Cardiac systolic/diastolic function, hypertrophy, and fibrosis were improved in the EVO-treated group. EVO prevented cardiac lipotoxicity by reducing the accumulation of lipid droplets in the myocardium through suppression of CD36, ACSL1, FABP3, PPARgamma, and DGAT1 and enhancement of the phosphorylation of FOXO1, indicating its inhibition. The EVO-mediated improvement in mitochondrial function and reduction in damage were achieved through activation of PGC1a/NRF1/TFAM, which activates mitochondrial biogenesis. RNA-seq results for the whole heart confirmed that EVO treatment mainly affected the differentially expressed genes (DEGs) related to lipid metabolism. Collectively, these findings demonstrate that EVO improves cardiac function by reducing lipotoxicity and mitochondrial injury and provides a potential therapeutic option for DCM.

The Vietnam Osteoporosis Study: Rationale and design

Lan T. Ho-Pham,Tuan V. Nguyen 대한골다공증학회 2017 Osteoporosis and Sarcopenia Vol.3 No.2

Objectives: Osteoporosis and fracture impose a significant health care burden on the contemporary populations in developing countries. The Vietnam Osteoporosis Study (VOS) sought to assess the burden of osteoporosis and its comorbidities in men and women. Methods: The study was designed as a population-based family investigation in which families were randomly recruited from Ho Chi Minh City, Vietnam. Individuals were assessed for bone health, including bone mineral density (BMD) and body composition and trabecular and cortical bone properties by pQCT (peripheral quantitative computed tomography). Fasting blood samples were obtained for the analysis of plasma glucose, glycosylated hemoglobin, and bone turnover markers. Genomic DNA extraction from whole blood samples for further genetic and genomic analyses. Results: We have recruited more than 4157 individuals from 817 families. The average age of participants was 51, with approximately 45% of the individuals aged 50 years and older. Approximately 3% of participants were obese (body mass index ? 30 kg/m2), and 21% were overweight. Notably, 11% of participants aged 40 years and older were diabetic. Among those aged 50 years and older, approximately 14% of women and 5% of men had osteoporosis (i.e., femoral neck BMD T-scores ? ?2.5). There were modest correlations between volumetric BMD and areal BMD. Conclusions: VOS is a major bone research project in Vietnam aimed at comprehensively documenting the burden osteoporosis, its co-occurrence of chronic diseases, and their underlying etiologies. The Study will make important contributions to the literature of bone health worldwide.

Effect of Grafting Position, Water Content in Substrate on the Survival Rate and Quality of Grafted Tomato Seedlings

박혜선 ( N. T. Vu ),허재윤 ( S. H. Kim ),박영식 ( T. D. Pham ),박성민 ( I. S. Kim ) 강원대학교 농업생명과학연구원(구 농업과학연구소) 2015 강원 농업생명환경연구 Vol.27 No.2

The objective of this study was conducted to determine effects of grafting position and water content in the substrate on the survival rate and quality of grafted tomato seedlings. Two grafting positions including above and below the rootstock cotyledons were examined. In addition, three water content levels (mid (control), high and low) in thesubstrate were set up during healing and acclimatization processes. There was no difference in survival rate between two grafting positions, but grafting positions effected on growth of grafted seedlings. The growth parameters and root morphology of seedlings grafted above the rootstock cotyledons were higher than that in seedlings grafted below the rootstock cotyledons, except leaf chlorophyll value and T/R ratio. The maximum survival rate (100%) was observed in mid (control) and high water treatments, but the survival rate (95.3%) decreased in low water treatment. The tallest plant height and largest leaf area were obtained in high water treatment. Leaf chlorophyll content significantly increased in low water treatment. No significant difference was detected among different water treatment with stem diameter, number of leaves. Grafted seedling in low water treatment significantly decreased fresh and dry weight of shoot and root. T/R ratio increased in low water treatment, but it was similar in mid and high water treatments. The high compactness value was observed in mid water treatment. The high values of total root surface area, total root length, and number of root tips were observed in high water treatment. However, there was no significant difference between mid (control) and low water treatments on total root surface area, total root length, and number of toot tips.

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>

Discordance between quantitative ultrasound and dual-energy X-ray absorptiometry in bone mineral density: The Vietnam Osteoporosis Study

Huy G. Nguyen,Khanh B. Lieu,Thao P. Ho-Le,Lan T. Ho-Pham,Tuan V. Nguyen 대한골다공증학회 2021 Osteoporosis and Sarcopenia Vol.7 No.1

Objectives: Calcaneal quantitative ultrasound measurement (QUS) has been considered an alternative to dual-energy X-ray absorptiometry (DXA) based bone mineral density (BMD) for assessing bone health. This study sought to examine the utility of QUS as an osteoporosis screening tool by evaluating the correlation between QUS and DXA. Methods: The study was a part of the Vietnam Osteoporosis Study that involved 1270 women and 773 men aged 18 years and older. BMD at the femoral neck, total hip and lumbar spine was measured using DXA. Osteoporosis was diagnosed based on the femoral neck T-score using World Health Organization criteria. Broadband ultrasound attenuation (BUA) at the calcaneus was measured by QUS. The concordance between BUA and BMD was analyzed by the linear regression model. Results: In all individuals, BUA modestly correlated with femoral neck BMD (r ¼ 0.35; P < 0.0001) and lumbar spine BMD (r ¼ 0.34; P < 0.0001) in both men and women. In individuals aged 50 years and older, approximately 16% (n ¼ 92/575) of women and 3.2% (n ¼ 10/314) of men were diagnosed to have osteoporosis. Only 0.9% (n ¼ 5/575) women and 1.0% (n ¼ 3/314) men were classified as “Low BUA”. The kappa coefficient of concordance between BMD and BUA classification was 0.09 (95% CI, 0.04 to 0.15) for women and 0.12 (95% CI, 0.03 to 0.22) for men. Conclusions: In this population-based study, QUS BUA modestly correlated with DXA BMD, suggesting that BUA is not a reliable method for screening of osteoporosis

Brevundimonas albigilva sp. nov., isolated from forest soil

Pham, V. H. T.,Jeong, S.,Chung, S.,Kim, J. Microbiology Society 2016 International journal of systematic and evolutiona Vol.66 No.-

<P>Strain NHI-13(T), a Gram-stain-negative, aerobic and short rod-shaped bacterium, was isolated from forest soil at Kyonggi University in Suwon, South Korea. It grew optimally in R2A medium, at 20-30 degrees C, in the presence of 0-4 % NaCl. Colonies resulting from incubation of the strain on agar plates for 2 days were circular, raised, translucent, viscous and whitish-yellow, with entire margins. This strain exhibited high catalase activity but was negative for oxidase. 16S rRNA gene sequence analysis showed that strain NHI-13(T) formed a coherent cluster with members of the genus Brevundimonas. Its similarities were 98.0 % with Brevundimonas aurantiaca DSM 4731(T), 97.9 % with Brevundimonas vesicularis LMG 2350(T), 97.6 % with Brevundimonas intermedia ATCC 15262(T), 97.5 % with Brevundimonas nasdae GTC 1043(T), 97.1 % with 'Brevundimonas olei ' MJ15, 97.1 % with Brevundimonas mediterranea V4.BO.10(T) and 97.0 % with Brevundimonas poindexterae FWC40(T). The major cellular fatty acids were summed feature 8 (C-18 : 1 omega 7c/C-18 : 1 omega 6c), C-16 : 0 and 11-methyl C-18 : 1 omega 7c. The DNA G+C content was 63 mol%. The predominant quinone was ubiquinone Q-10. The polar lipid profile contained 1,2-di-O-acyl-3-O-alpha-D-glycopyranuronosyl glycerol, 1,2-di-O-acyl-3-O-alpha-D-glycopyranosyl glycerol, 1,2-di-O-acyl-3-O-[D-glycopyranosyl (1 -> 4)-alpha-D-glucopyranuronosyl] glycerols, phosphatidylglycerol, 1,2-diacyl-3-O-(6'-phosphatidyl-alpha-D-glucopyranosyl) glycerol and other unknown lipids. The DNA relatedness of strain NHI-13(T) with its reference strains was in the range of 43-56 %. On the basis of its phenotypic, genotypic, chemotaxonomic and phylogenetic distinctiveness, strain NHI-13(T) is suggested to be a representative of a novel species, belonging to the genus Brevundimonas. Therefore, the name Brevundimonas albigilva. sp. nov. is proposed, with the type strain being NHI-13(T) (=KEME 9005-016(T)=KACC 18249(T)=JCM 30385(T)).</P>

EXPLICIT ITERATIVE METHODS FOR MAXIMAL MONOTONE OPERATORS IN HILBERT SPACES

Nguyen T. T. Thuy,Pham T. T. Hoai,Nguyen T. T. Hoa 경남대학교 기초과학연구소 2020 Nonlinear Functional Analysis and Applications Vol.25 No.4

In this paper, we introduce new explicit iterative methods for solving a variationalinequality problem over the set of zeros for a maximal monotone operator in Hilbertspaces. By using two resolvents of the monotone operator at each iterate, we prove strongconvergence of the methods under a general condition on resolvent parameter. As specialcases, new contraction and generalized proximal point methods are obtained. An exampleis given for illustration and comparison.