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Dong Van VU1,Tai Van PHAM2,Ghi Nha TRAN3,Anh Phuong Thi NGUYEN4,Cong Van NGUYEN5 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6
This study seeks to examine the relationship between business resources (through VRIN: Valuable - valuable, Rare - scarce; Inimitable - difficult to adapt, Irreplaceable - hard to replace), dynamic capability, external cooperation, and efficiency of startups operating in the seafood export sector. Research data was collected randomly and conveniently from 250 enterprises in Ba Ria-Vung Tau province, Vietnam, from October 2020 to December 2020. After excluding those ineligible, the remaining 204 enterprises meet the research conditions. With the support of SPSS-AMOS 22 dedicated software, using the 5-step Likert scale and Structural Equation Modeling (SEM), the study conducted analysis steps such as verifying convergence, discriminant value, unidirectional and scale reliability when giving the components correlated freely in the critical model by Confirmatory Factor Analysis (CFA) analysis. Results of the study have shown that the enterprise resource factor - VRIN has a positive impact on dynamic capability, and outside cooperation. However, in contrast to previous studies, we found that the relationship between enterprise resources - VRIN and performance as well as the relationship between dynamics capacity and performance is not clear. This shows that seafood exporters need to promote, exploit and effectively use this precious resource to improve business efficiency.
Alpha-Glucosidase Inhibitory Activity of Saponins Isolated from Vernonia gratiosa Hance
Cong Pham Van,Anh Hoang Le Tuan,Vinh Le Ba,Han Yoo Kyong,Trung Nguyen Quang,Minh Bui Quang,Duc Ngo Viet,Ngoc Tran Minh,Hien Nguyen Thi Thu,Manh Hoang Duc,Lien Le Thi,Lee Ki Yong 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.6
Species belonging to the Vernonia (Asteraceae), the largest genus in the tribe Vernonieae (consisting of about 1,000 species), are widely used in food and medicine. These plants are rich sources of bioactive sesquiterpene lactones and steroid saponins, likely including many as yet undiscovered chemical components. A phytochemical investigation resulted in the separation of three new stigmastane-type steroidal saponins (1 – 3), designated as vernogratiosides A–C, from whole plants of V. gratiosa. Their structures were elucidated based on infrared spectroscopy (IR), one-dimensional (1D) and two-dimensional nuclear magnetic resonance (2D NMR), high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and electronic circular dichroism analyses (ECD), as well as chemical reactivity. Molecular docking analysis of representative saponins with αglucosidase inhibitory activity was performed. Additionally, the intended substances were tested for their ability to inhibit α-glucosidase activity in a laboratory setting. The results suggested that stigmastane-type steroidal saponins from V. gratiosa are promising candidate antidiabetic agents.
Pham-Cong, De,Kim, Su Jae,Jeong, Se Young,Kim, Jong-Pil,Kim, Hyun Gyu,Braun, Paul V.,Cho, Chae-Ryong Elsevier 2018 Carbon Vol.129 No.-
<P><B>Abstract</B></P> <P>Nitrogen-doped carbon-coated and graphene oxide-wrapped Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles were prepared using the electrostatic force between polyethyleneimine-functionalized Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles and graphene oxide layers, followed by annealing in an N<SUB>2</SUB> atmosphere (Fe<SUB>3</SUB>O<SUB>4</SUB>@NCG). The electrochemical performance of Fe<SUB>3</SUB>O<SUB>4</SUB>@NCG was superior to that of graphene oxide- or reduced graphene oxide-wrapped Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles and carbon-coated Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles. Fe<SUB>3</SUB>O<SUB>4</SUB>@NCG exhibited stable specific capacity of ∼895 mAh g<SUP>−1</SUP> after 350 cycles over the voltage range 0.001–3.0 V vs. Li/Li<SUP>+</SUP>. The superior performance of Fe<SUB>3</SUB>O<SUB>4</SUB>@NCG was attributed to the presence of a nitrogen-doped carbon layer and networks of reduced graphene oxide. The chemical route-derived Fe<SUB>3</SUB>O<SUB>4</SUB>@NCG may be a promising anode material for high-performance lithium-ion batteries.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Pham-Cong, D.,Ahn, K.,Hong, S.W.,Jeong, S.Y.,Choi, J.H.,Doh, C.H.,Jin, J.S.,Jeong, E.D.,Cho, C.R. Elsevier 2014 CURRENT APPLIED PHYSICS Vol.14 No.2
In this study, vanadium pentoxide (V<SUB>2</SUB>O<SUB>5</SUB>) nanowires (NWs) with a diameter of 100-200 nm and a length of up to several micrometers as cathode for lithium ion batteries are synthesize using an electrospinning method. The reduced graphene oxide (rGO) and V<SUB>2</SUB>O<SUB>5</SUB> NWs (GVO) composites are form by wet mixing the electrospun V<SUB>2</SUB>O<SUB>5</SUB> NWs and rGO. Surface morphologies, microstructure and elemental mapping, and chemical bonding states of the composites are characterize. The initial and 60 cycles discharge capacities of GVO composite composed of 1 wt% rGO show up to 225 mAh g<SUP>-1</SUP> and 125 mAh g<SUP>-1</SUP>, even higher than pure V<SUB>2</SUB>O<SUB>5</SUB> NWs, when the lithium ion battery cycled between 2.0 and 4.0 V with a rate of 0.2 C, because of highly conductive rGO. The GVO composite could be promising as a high performance cathode for lithium ion batteries.
Pham-Cong, De,Choi, Jun Hee,Yun, Jeongsik,Bandarenka, Aliaksandr S.,Kim, Jinwoo,Braun, Paul V.,Jeong, Se Young,Cho, Chae Ryong American Chemical Society 2017 ACS NANO Vol.11 No.1
<P>As potential high-performance anodes for Li-ion batteries (LIBs), hierarchical heteronanostructures consisting of TiNb2O7 nanofibers and ultrathin MoS2 nanosheets (TNO@MS HRs) were synthesized by simple electrospinning/hydrothermal processes. With their growth mechanism revealed, the TNO@MS HRs exhibited an entangled structure both for their ionic and electronic conducting pathways, which enabled the synergetic combination of one-and two-dimensional structures to be realized. In the potential range of 0.001-3 V vs Li/Li+, the TNO@MS HR-based LIBs exhibited high capacities of 872 and 740 mAh g(-1) after 42 and 200 cycles at a current density of 1 A g(-1), respectively, and excellent rate performance of 611 mAh g(-1) at 4 A g(-1). We believe that the fabrication route of TNO@MS HRs will find visibility for the use of anode electrodes for high capacity LIBs at low cost.</P>
Pham-Cong, De,Park, Jung Soo,Kim, Jae Hyun,Kim, Jinwoo,Braun, Paul V.,Choi, Jun Hee,Kim, Su Jae,Jeong, Se Young,Cho, Chae Ryong Elsevier 2017 Carbon Vol.111 No.-
<P>SnO2 hollow nanofibers (SnO2 hNFs) are prepared through electrospinning and annealing processes. The polypyrrole layers coated onto the surface of the SnO2 hNFs are annealed in a nitrogen atmosphere. The nitrogen-doped carbon-coated SnO2 hNFs (SnO2/NC hNFs) are composed of SnO2 hNFs with a wall thickness of 60-80 nm and a nitrogen-doped carbon layer similar to 10 nm thick. The nitrogen content in the carbon layer is approximately 7.95%. Owing to the nitrogen-doped carbon shell layers, the specific reversible capacity of SnO2/NC hNFs at a current density of 0.2 A g(-1) after 100 cycles is 1648 mAh g(-1) which is 427% higher than that of (386 mAh g(-1)) SnO2 hNFs. This strategy may open new avenues for the design of other composite architectures as electrode materials in order to achieve high-performance lithium ion batteries. (C) 2016 Elsevier Ltd. All rights reserved.</P>
Pham-Cong, De,Kim, Jinwoo,Tran, Van Tan,Kim, Su Jae,Jeong, Se-Young,Choi, Jun-Hee,Cho, Chae Ryong Elsevier 2017 ELECTROCHIMICA ACTA Vol.236 No.-
<P><B>Abstract</B></P> <P>We synthesized polycrystalline Ti<SUB>2</SUB>Nb<SUB>10</SUB>O<SUB>29</SUB> nanofibers (NFs) via a simple post-annealing process of as-electrospun polymeric NFs as an anode material for Li-ion batteries (LIBs). During the first discharge/charge process, the Ti<SUB>2</SUB>Nb<SUB>10</SUB>O<SUB>29</SUB> NFs annealed at 900°C exhibited insertion/extraction capacities of up to 344 and 304mAhg<SUP>−1</SUP>, corresponding to 19.1 and 16.7mol Li<SUP>+</SUP> per formula unit, respectively. This material exhibited excellent rate capability (93mAhg<SUP>−1</SUP> at 15Ag<SUP>−1</SUP>) and a higher average diffusion coefficient (D<SUB>Li</SUB> =∼1.5×10<SUP>−12</SUP> cm<SUP>2</SUP> s<SUP>−1</SUP>) than Ti<SUB>2</SUB>Nb<SUB>10</SUB>O<SUB>29</SUB> powder (∼6.9×10<SUP>−13</SUP> cm<SUP>2</SUP> s<SUP>−1</SUP>). This performance can be attributed to the unique nanostructure of firmly interconnected, highly crystalline Ti<SUB>2</SUB>Nb<SUB>10</SUB>O<SUB>29</SUB> nano-grains, which facilitates the Li<SUP>+</SUP> and electron transport. The kinetics obtained from current-voltage curves indicate a mixture of diffusion-limited and capacitive processes. The suggested electro-spinning/post annealing approach can effectively provide a simple route towards high-quality Ti<SUB>2</SUB>Nb<SUB>10</SUB>O<SUB>29</SUB> NF-based anodes for high-performance LIBs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ti<SUB>2</SUB>Nb<SUB>10</SUB>O<SUB>29</SUB> nanofibers and powders are fabricated by electrospinning and solid-state reaction process. </LI> <LI> Linearly connected single crystal nanofibers are formed. </LI> <LI> Rate capability and cycle stability of the nanofibers are enhanced compared to the powders. </LI> <LI> Diffusion behaviors of Li ion through the Ti<SUB>2</SUB>Nb<SUB>10</SUB>O<SUB>29</SUB> single crystallite are better than other samples. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
D. Pham-Cong,K. Ahn,홍석원,정세영,J.H. Choi,C.H. Doh,J. S. Jin,정의덕,조채용 한국물리학회 2014 Current Applied Physics Vol.14 No.2
In this study, vanadium pentoxide (V2O5) nanowires (NWs) with a diameter of 100e200 nm and a length of up to several micrometers as cathode for lithium ion batteries are synthesize using an electrospinning method. The reduced graphene oxide (rGO) and V2O5 NWs (GVO) composites are form by wet mixing the electrospun V2O5 NWs and rGO. Surface morphologies, microstructure and elemental mapping, and chemical bonding states of the composites are characterize. The initial and 60 cycles discharge capacities of GVO composite composed of 1 wt% rGO show up to 225 mAh g1 and 125 mAh g1, even higher than pure V2O5 NWs, when the lithium ion battery cycled between 2.0 and 4.0 V with a rate of 0.2 C, because of highly conductive rGO. The GVO composite could be promising as a high performance cathode for lithium ion batteries.