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Results 51-60 of 144 (Search time: 0.002 seconds).
  • Authors: Ngoc Khanh Pham; Huu Tai Bui; Thu Huong Tran; Thi Ngoc Anh Hoang; Thi Ha Vu; Dinh Tung Do; Young Ho Kim; Seok Bean Song; Dao CuongTo; Manh Cuong Nguyen;  Advisor: -;  Co-Author: - (2021)

    Dysoxylum tpongense Pierre (local name ‘Huynh Dan Bap’) belonging to family Meliaceae, is a tree (3–10 m height), distributed in the mountainous areas (ca. 1000 m a.s.l.) in North Vietnam. From the dichloromethane fraction of the methanol extract of the leaves and stems of this plant, six dammarane triterpenes, one furanoid diterpene together with three sterols were isolated. Evaluation of biological activities of isolated compounds showed that cabraleahydroxylactone (5), cabraleahydroxylactone 3-acetate (6), and stigmast-4-en-3-one (10) possessed an anti-inflammatory effect against Liver X receptor (LXR) activation in HepG2 cell line model with IC50 values of 20.29 ± 3.69, 24.32 ± 2.99, and 7.09 ± 0.97 (μM), respectively. While three other triterpenoid compounds aglinin C 3- acetat...

  • Authors: Phong Thanh Vo; Huu The Nguyen; Hai Thi Trinh; Viet Minh Nguyen; Anh-Tuan Le; Huy QuangTran; Thuy Thi Thu Nguyen;  Advisor: -;  Co-Author: - (2021)

    For mitigating environmental pollution caused by excess usage of urea fertilizer, this paper reports a new fertilizer formulation, based on urea incorporating chitosan (CS) and poly (vinyl alcohol) (PVA) blend, for the slow release of urea. The urea/CS/PVA formulations were prepared by cross-linking CS and PVA blend in the presence of urea with glutaraldehyde as a cross-linker. The results indicated an interaction between urea and the functional groups of CS and PVA through hydrogen bonding, which has significant effects on the thermal properties of urea/CS/PVA formulation. The surface morphology of urea/CS/PVA formulations showed that the quantity of urea crystals anchored on the surface increased with the contents of urea and the cross-linking agent. Urea/CS/PVA formulations with ...

  • Authors: Vu Huu Nhu;  Advisor: -;  Co-Author: - (2021)

    This work is concerned with second-order necessary and sufficient optimality conditions for optimal control of a non-smooth semilinear elliptic partial differential equation, where the nonlinearity is the non-smooth max-function and thus the associated control-to-state operator is, in general, not Gâteaux-differentiable. In addition to standing assumptions, two main hypotheses are imposed. The first one is the Gâteaux-differentiability at the considered control of the objective functional and it is precisely characterized by the vanishing of an adjoint state on the set of all zeros of the corresponding state. The second one is a structural assumption on the sets of all points at which the values of the interested state are ‘close’ to the non-differentiability point of the max-functi...

  • Authors: Tapanainen, Tommi;  Advisor: Dao, Trung Kien; Nguyen, Thi Thanh Hai;  Co-Author: - (2021)

    Electronic word of mouth (eWOM), enabled by social media, has been widely recognized as an influential marketing tool. It has been suggested that personality influences how people accept information originating in eWOM, but most research has not connected personalities with behavioral intention or information use. This study aimed to assess the link between eWOM and personalities on intention to choose a tourism destination. The research model was developed from the Big Five personality model and the information adoption model (IAM). An analysis of 647 participants in Vietnam confirmed that IAM can predict behavioral intention for tourism destinations, thereby adding to the literature, which so far has mainly utilized the technology adoption model. The result also shows that persona...

  • Authors: Viet ThongLe; HanjunRyu; Sang A.Han; HaoVan Bui; Viet HuongNguyen; NguyenVan Hieu; Ju-HyuckLee; Sang-WooKim; Young HeeLee;  Advisor: -;  Co-Author: - (2021)

    Despite their high power density, aqueous-based electric double-layer capacitors (EDLCs) possess relatively low energy density due to the limitation of potential window (~1.0 V) and low specific capacitance of active materials. To increase the energy density without sacrificing the power density, it is highly desired to achieve a simultaneous improvement of both specific capacitance and potential window of EDLCs. However, this remains a major challenge that is not been solved up to date. This work demonstrates that by inserting a polarized-polyvinylidene fluoride (PVDF) ferroelectric layer underneath the graphene, a simultaneous enhancement of both areal capacitance and potential window is achieved, in which the areal capacitance increases from 5.5 to 7.5 μF/cm2 (i.e., 36%) (or 55 F...

  • Authors: Tuan Nguyen Van; Phong Dinh Van; Hung Nguyen Chi; Hoang Tran Viet;  Advisor: -;  Co-Author: - (2021)

    Autonomous Underwater Vehicle (AUV) has become the main tool for exploring the oceans in the fields of science, the military and the marine economy... However, the energy problem for AUV has always been of interest to many researchers. AUV’s missions are time-limited by constraints of onboard vehicle power. Most missions are therefore short, from 4 to 15 hours duration. Solar energy is an effective renewable energy source and has increasingly been used in many fields. We can see that if the Solar Autonomous Underwater Vehicles (S-AUV) has the little surface area then the efficiency of solar collector is low. Hence, we need to optimize the structure of S-AUV. When designing a SAUV in particular and an AUV in general, one of the first concerns is structural shapes, energy and propulsi...

  • Authors: Kee Young Hwang; Valery Ortiz Jimenez; Baleeswaraiah Muchharla; Tatiana Eggers; Anh-Tuan Le; Vu Dinh Lam; Manh-Huong Phan;  Advisor: -;  Co-Author: - (2021)

    Breathing is vital to life. Therefore, the real-time monitoring of a patient′s breathing pattern is crucial to respiratory rehabilitation therapies, such as magnetic resonance exams for respiratory-triggered imaging, chronic pulmonary disease treatment, a

  • Authors: Nguyen, Huu Tuan;  Advisor: Ryu, Shinyoung; Duong, Anh Tuan; Lee, Soonil;  Co-Author: - (2021)

    We report a five-fold luminance increase of green-light-emitting CdSe@ZnS quantum-dot LEDs (QLEDs) in response to treatment with a 2-ethoxyethanol solution of cesium carbonate (Cs2CO3). The maximum luminous yield of Cs2CO3-treated QLED is as high as 3.41 cd A−1 at 6.4 V. To elucidate device-performance improvement, we model measured currents as the sum of radiative and non-radiative recombination components, which are respectively represented by modified Shockley equations. Variations in model parameters show that a shift in Fermi level, reduction of barrier heights, and passivation of mid-gap defect states are the main results of Cs2CO3 treatment. In spite of a large luminance difference, light-extraction efficiency remains the same at 9% regardless of Cs2CO3 treatment because of t...

  • Authors: Tran Dinh Cuong; Anh D.Phan;  Advisor: -;  Co-Author: - (2021)

    Iron represents the principal constituent of the Earth's core, but its high-pressure melting diagram remains ambiguous. Here we present a simple analytical approach to predict the melting properties of iron under deep-Earth conditions. In our model, anharmonic free energies of the solid phase are directly determined by the moment expansion technique in quantum statistical mechanics. This basis associated with the Lindemann criterion for a vibrational instability can deduce the melting temperature. Moreover, we correlate the thermal expansion process with the shear response to explain a discontinuity of atomic volume, enthalpy, and entropy upon melting. Our numerical calculations are quantitatively consistent with recent experiments and simulations. The obtained results would improve...