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Artocarpus nigrifolius: Cytotoxic and Antibacterial Constituents
Tran Minh Hoi,김영호,Ha Van Anh,Nguyen Thi Thanh Huong,Nguyen Van Tuyen,Le Thi Tu Anh,Nguyen Thanh Tra,Ba Thi Cham,Nguyen Thi Thu Ha,Pham Thuy Linh,Doan Duy Tien,Phan Van Kiem,Ninh Khac Ban,Lidziya Kukha 한국응용생명화학회 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.6
Six known compounds including α-amyrin 3-acetate (1), β-sitosterol (2), betulinic acid (3), friedelan-3-one (4),artochamin B (5), and 2-C-methyl-D-erythritol 4-O-α-D-glucopyranoside (6) were isolated from the stem barks and leaves of Artocarpus nigrifolius (Moraceae) for the first time. Their structures were identified by spectroscopic methods as well as comparison with literatures. Cytotoxicity and antibacterial activity of 1-6 were evaluated. Results showed that artochamin B (5)possessed the highest cytotoxicity towards MCF7, Lu, HepG2,and KB cell lines with IC50 values of 4.59, 20.00, 3.60, and 1.18μg/mL, respectively. It also inhibited the growth of Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus), whereas inactive on the growth of both Gram-negative bacteria and yeast.
Unipolar Resistance Switching Characteristics in a Thick ZnO/Cu/ZnO Multilayer Structure
Tran Le,Hoang Cao Son Tran,Van Hieu Le,Tuan Tran,Cao Vinh Tran,Thanh Tan Vo,Mau Chien Dang,김상섭,이재찬,Bach Thang Phan 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7
The resistance switching mechanism and the electrical conduction of thick Cu/ZnO/Cu/ZnO/Cu structures were investigated for various ZnO thicknesses (40, 80, 160, and 320 nm) when the thickness of the middle Cu layer was 2 nm. The ZnO films had a microstructure with columnar grains normal to the substrate. The switching voltages (VSET and VRESET) varied with the thickness of the ZnO layer. A symmetric electrode structure exhibited a unipolar resistance switching. The electrical transport of both high-resistance state (HRS) and low-resistance state (LRS) was Ohmic conduction, and the resistance switching mechanism was driven by the formation and the rupture of Cu conducting paths.
Dielectric resonance effect with negative permittivity in a La1.5Sr0.5NiO4+δ ceramic
Tran Dang Thanh,Nguyen Van Dang,Le Van Hong,The-Long Phan,Seong-Cho Yu 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.10
A polycrystalline sample of La1.5Sr0.5NiO4+δ was prepared by using a solid-state reaction. Xraydiffraction proved the sample to be a single phase with a tetragonal structure (space group:I4/mmm). By using an iodometric titration method to determine the non-stoichiometric oxygenconcentration (δ) in La1.5Sr0.5NiO4+δ, we found δ = −0.017, which corresponds to a doping level ofnh = x + 2δ = 0.466. Also, a strong increase of the magnetization in theM(T) curve at temperaturesbelow the spin-ordering temperature (TSO 100 K) was observed. The M(H) curves show verysmall magnetic moments, which proves the weak ferromagnetic nature of La1.5Sr0.5NiO4+δ. Thedependences of the dielectric constant on the frequency and the temperature, "(!, T) = "0(!, T) +i"00(!, T), was investigated in the frequency range of 1 − 13 MHz. At temperatures around roomtemperature, the maximum of the real part ("0) was higher than 105. Particularly, an abnormaldependence of the permittivity on frequency was observed. Depending on temperature, a dielectricresonance was observed at about 500 kHz or 8 MHz. Interestingly, we observed the dielectricresonanceeffect with a negative permittivity. Such a feature is very similar to that observed inleft-handed materials. The fitting of the experimental data for the dielectric constant at frequenciesaround the resonance frequency to the equations associated with an equivalent RLC series circuitproves that La1.5Sr0.5NiO4+δ belongs to the class of multiferroic materials.
Conventional and inverse magnetocaloric effects, and critical behaviors in Ni43Mn46Sn8In3 alloy
Tran Dang Thanh,W.Z. Nan,Gnu Nam,Hoang Thanh Van,유태수,판더롱,S. C. Yu 한국물리학회 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 Ni43Mn46Sn8In3 has been performed. Our results reveal the sample exhibiting structural and magnetic phase transitions at temperatures TC M = 166 K (TC of the martensitic phase), TM-A =260 K (the martensitic-to-austenitic phase transformation) and TC A = 296 K (TC of the austenitic phase). The large values of refrigerant capacity (RC) around TMeA and TC A are found to be RCM-A = 172.6 and RCA = 155.9 J kg-1, respectively, under an applied field change of 30 kOe. Our critical analyses near the TC M and TC A 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 TC A, the maximum magnetic entropy change (|ΔSmax|) versus magnetic field H obeys a power law, |ΔSmax| = a·Hn, where the exponent n is found to be about 0.66.
Magnetoresistance Effect in La1.5Sr0.5NiO4-Doped La0.7Ca0.3MnO3 Nanocomposites
Thanh, Tran Dang,Van, Hoang Thanh,Lee, Jong Suk,Yu, Seong-Cho Springer-Verlag 2017 Journal of superconductivity and novel magnetism Vol.30 No.3
<P>Our experimental results point out that most La1.5Sr0.5NiO4 nanoparticles were distributed at the grain boundaries and on the surfaces of the La0.7Ca0.3MnO3 nanoparticles. The nanocomposite samples exhibit a ferromagnetic-paramagnetic and a metal-insulator phase transitions at T (C) and T (MI), respectively. With increasing La1.5Sr0.5NiO4-doped content, T (C) value is almost unchanged while T (MI) value decreases from 251 K for an undoped sample to 65 K for 20 % La1.5Sr0.5NiO4-doped one. Particularly, the La1.5Sr0.5NiO4-doped samples higher than 20 % exhibit the insulating properties in the whole temperature range. Magnetoresistance effect at low field (H= 3 kOe) of all the samples is observed. In order to explore the nature of their magnetoresistance effect at low field according to temperature and magnetic field change, we analyzed carefully the obtained data based on the phenomenological model related to the spinpolarized transport of conduction electrons at grain boundaries. With this, the temperature dependences of magnetoresistances (including the intrinsic magnetoresistances and spinpolarized transport magnetoresistances) can be described well by an expression of the Curie-Weiss law-like behavior, a + b/(c + T). We also have been able to observe the percolation threshold in this system for 25 % of La1.5Sr0.5NiO4 component, and around this critical point a great increase of magnetoresistances has been detected.</P>
Effect of hydrothermal time on the structure and property of graphene oxide membrane
Tran Van Khai,Pham Thuy Trang,Le Ngoc Long,Le Van Thang,Tran Duc Chau,Vuong Vinh Dat,Mai Thanh Phong 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4
Two dimensional graphene oxide (GO) has potential application in membrane separation owing to its unique structure andphysicochemical properties. In this study, the reduced graphene oxide (rGO) was synthesized from GO via hydrothermaltreatment at 160 oC for 1, 2, 3 and 4 h, and the rGO membranes were prepared on cellulose nitrate supporting membranesby vacuum filtration. The structural change and chemical composition of GO were investigated using X-ray diffraction (XRD),Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM),atomic force microscopy (AFM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) andcontact angle measurements. The result shows that uniformly intact rGO membranes with good hydrophobicity could beachieved by adjusting the reduction degree of GO through changing the hydrothermal reaction time. The huge improvementof the hydrophobic property of rGO could be attributed to the removal of the most the hydrophilic oxygen-containingfunctional groups on the surface of GO. Additionally, the structure, chemical composition, and d-spacing of the GO can alsobe controlled by adjusting the reduction time. This method holds great potential because it can be prepared in large quantitiesat low cost, and suitable for applications in membrane technologies.
A dense, pinholes-free pure cubic phase CsPbBr3 nanocrystals film for high-performance photodetector
Thanh-Tung Duong,Phuong-Nam Tran,Tuan-Pham Van,Duy-Hung Nguyen,Van-Dang Tran 대한금속·재료학회 2024 ELECTRONIC MATERIALS LETTERS Vol.20 No.2
This study demonstrates a simple centrifugal coating method to prepare high-quality pure cubic phase CsPbBr 3 nanocrystalfi lm. The resultant perovskite layers possess a uniform and dense 500 nm-thick, with a bandgap of 2.38 eV, a low trap-statedensity of 6.9 × 10 − 15 cm − 3 , and carrier mobility of approximately 19.8 cm 2 V − 1 s − 1 . Furthermore, CsPbBr 3 NCs-basedself-powered photodetectors with high charge carriers’ charge transfer are fabricated. The device shows a low dark currentdensity of 1.93 × 10 − 7 A/cm 2 at room temperature. Such photodetectors show the highest responsivity of 3.0 AW − 1 ,specifi c detectivity of 1.2 × 10 13 Jones, and external quantum effi ciency (EQE) of 920% at zero bias voltage. The proposedmethod shows signifi cant promise for use in the lab fabrication of optoelectronic devices based on thin fi lms of nanocrystalperovskite materials.