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  • Authors: Ho, Nang X.; Vu, Truong V.; Nguyen, Vinh T.; Nguyen, Cuong T.; Vu, Hung V.;  Advisor: -;  Co-Author: - (2021)

    Droplets resulting from liquid filament contraction have been widely used in industrial processes. However, detailed investigations of liquid compound filament contraction processes are lacking in the literature. Therefore, this study provides a numerical investigation of the contraction of a two-layered compound filament. The simulations are based on an axisymmetric front-tracking method. It is found that because of the interfacial tension force, the initially long cylindrical filament contracts to a compound droplet without any breakup or breaks up into smaller droplets during contraction. Unlike simple filaments, the presence of the inner filament inside the compound filament results in a more complicated compound filament breakup process with various droplet types, e.g., simple ...

  • Authors: Das, Raja;  Advisor: Kalappattil, Vijaysankar; Phan, Manh-Huong; Srikanth, Hariharan;  Co-Author: - (2021)

    Magnetite has fascinated researchers for decades, due to its wide range of applications from spintronics to biomedicine. Despite a large body of works aimed at its magnetic properties, no consensus has been reached on the physical origin of the low temperature magnetic anomalies observed in magnetite. Although, a lot of work has been done in studying magnetite nanoparticles, but studies on the low temperature anomalies in those nanoparticles still remains unresearched. We report on the observation of the low temperature magnetic anomalies in highly crystalline, stoichiometric Fe3O4 nanorods and relate them to the coupled electron hopping relaxation process and domain wall motion. Both DC and AC susceptibility show the presence of a hump around 35 K, which is associated with the rela...

  • Authors: Nguyen, Hoe D.; Vu*, Truong V.; Nguyen, Phan H.; Pham, Binh D.; Ho, Nang X.; Nguyen, Cuong T.; Nguyen, Vinh T.;  Advisor: -;  Co-Author: - (2021)

    A compound droplet deforming in a constricted tube widely appears in drug delivery and microfluidic devices. In such a constriction, an indentation can present at the trailing surface of the droplet. However, this aspect has not been fully investigated and understood so far. This study focuses on the effects of some dimensionless parameters on the negative curvature, i.e., indentation, at the trailing surface of a compound droplet moving through a constricted tube. The presence of the constriction at the middle of the tube length enhances the droplet indentation. Numerical results were obtained for the capillary number Ca (varied in range of 0.1–1.0), the inner-to-outer droplet radius ratio R21 (varied in range of 0.2–0.9), the droplet-to-tube radius ratio R10 (varied in range of 0....

  • Authors: Tran, Vu Diem Ngoc; Le, Van Vinh; Vu, Lai Hoang; Nguyen, Ba Hung; Dinh, Thi Hinh; Pham, Ky Nam;  Advisor: -;  Co-Author: - (2021)

    This study investigated the structure evolution, surface morphology, dielectric properties, ferroelectric properties, piezoelectric properties, and electromechanical strain properties of lead-free (Bi0.5−xLax)(Na0.41K0.09)TiO3 piezoelectric ceramics. All samples were fabricated by a traditional solid-state synthesis. The effects of La3+-isovalent substituted on Bi3+-site of the Bi0.5Na0.41K0.09TiO3 system were examined. The addition of La doping in the Bi0.5Na0.41K0.09TiO3 ceramics induced the second phase of K4Ti3O8 and a crystal structural change from the rhombohedral and tetragonal phase to a pseudocubic phase. All samples show similar grain morphology and dense microstructure with the average grain size around 1.33 to 1.61 μm. The dielectric curves and field-induced polarization...

  • Authors: Phung, Cao Dai; Tran, Tuan Hiep; Choi, Ju-Yeon; Jeong, Jee-Heon; Ku, Sae Kwang; Yong, Chul Soon; Kim, Jong Oh;  Advisor: -;  Co-Author: - (2021)

    Cellular FLIP (cFLIP) is a crucial player of apoptosis-regulated pathways that is frequently overexpressed in solid cancers. To inhibit c-FLIP, pre- and post-transcriptionally, a multifunctional nanoparticle (NP) was created to deliver cFLIP-specific small interfering RNA (siRNA) into cancer cells. Specifically, Vorinostat (Vor)-loaded mesoporous silica nanoparticles (MSN) were conjugated with polyethylenimine-biotin (PB), followed by electrostatically binding with cFLIP siRNA (Vor/siR@MSN-PB). To stabilize and prolong the circulation time of nanoparticles, a bialdehyde-modified poly(ethylene glycol) (PEG) was cross-linked onto the polyethylenimine (PEI) backbone via the formation of the imine linkage (Schiff base) (Vor/siR@MSN-PB-PEG). The Schiff base is highly stable at physiologi...

  • Authors: Nguyen, Thuong T.H.;  Advisor: Nguyen, Thu-Thao; Tran, Thuan Van; Tan Lam; Danh, Luu Thai; Than, Van Thai;  Co-Author: - (2021)

    This study aims to introduce the antibacterial and antioxidant activities of the Piper betle Linn oil (PBLO) into chitosan film (pCS), named as pCS-PBLO film. The morphology, structure, and properties of the pCS-PBLO film, along with the PBLO concentration between 0.4% and 1.2% (v/v), were determined. The film surface became rough and heterogeneous with the addition of PBLO, which directly influenced on mechanical strength of the resultant film. The addition of the PBLO did not affect thermal stability but significant effect on flexibility and mobility of the film. Importantly, the film enhanced the UV-protective property and antioxidant activity as incorporated-PBLO. Moreover, the resulting film revealed the great inhibition efficiency against the negative-gram (E. coli, P. aerugin...

  • Authors: Thanh Tan Doan;  Advisor: Nathalie Bostel; Minh Hoàng Hà;  Co-Author: - (2021)

    The Vehicle Routing Problem (VRP) is one of the most studied topics in Operations Research. Among the numerous variants of the VRP, this research addresses the VRP with relaxed priority rules (VRP-RPR) in which customers are assigned to several priority groups and customers with the highest priorities typically need to be served before lower priority ones. Additional rules are used to control the trade-off between priority and cost efficiency. We propose a Mixed Integer Linear Programming (MILP) model to formulate the problem and to solve small-sized instances. A metaheuristic based on the Adaptive Large Neighborhood Search (ALNS) algorithm with problem-tailored components is then designed to handle the problem at larger scales. The experimental results demonstrate the performance o...

  • Authors: Minh-Hoang Nguyen;  Advisor: Huyen Thanh Thanh Nguyen; Tam-Tri Le; Anh-Phuong Luong; Quan-Hoang Vuong;  Co-Author: - (2021)

    Purpose The current review aims to examine the growth trajectory, most influential documents, intellectual and conceptual structure of the literature regarding gender issues in family business research. Design/methodology/approach The bibliometric analysis was performed using 224 documents from 1991 to 2020 extracted from the Web of Science database. Findings The review finds that this field's knowledge grew exponentially during the last three decades, mainly after 2003 and the last several years. Based on the co-citation analysis, three major research lines are identified: “Women's challenges and opportunities in the family business”, “Gender diversity in the family business corporate board”, and “Gender and family SMEs management.” The temporal co-word analysis reveals th...

  • Authors: Orfanoudaki, Maria;  Advisor: Hartmann, Anja; Alilou, Mostafa; Mehic, Naida; Kwiatkowski, Marcel; Jöhrer, Karin; Nguyen, Ngoc Hieu; Hensel, Andreas; Greil, Richard; Ganzera, Markus;  Co-Author: - (2021)

    The class of demosponges is the biggest and most diverse of all described sponge species and it is reported to produce a plethora of chemically different metabolites with interesting biological activities. The focus of the present study was to investigate the chemical composition of two Mediterranean demosponges, targeting their brominated compounds and prenylated hydroquinones, compounds with interesting cytotoxic and anti-microbial properties. In order to gain a deeper insight into the chemical diversity of their metabolites and their activities, 20 pure secondary metabolites including new natural products were isolated from two different species (Aplysina aerophoba and Spongia sp.) using various chromatographic techniques. Their structures were confirmed by NMR and HRMS, revealin...

  • Authors: Vuong, Quan-Hoang;  Advisor: La, Viet-Phuong; Ho, Manh-Toan; Pham, Thanh-Hang; Vuong, Thu-Trang; Vuong, Ha-My; Nguyen, Minh-Hoang;  Co-Author: - (2021)

    Science, technology, engineering, and mathematics (STEM) education has become a critical factor in promoting sustainable development. Meanwhile, book reading is still an essential method for cognitive development and knowledge acquisition. In developing countries where STEM teaching and learning resources are limited, book reading is an important educational tool to promote STEM. Nevertheless, public data sets about STEM education and book reading behaviors in emerging countries are scarce. This article, therefore, aims to present a data set of 4,966 secondary school students from a school-based data collection in Vietnam. The data set comprises of five major categories: 1) students' personal information (including STEM performance), 2) family-related information, 3) book reading pr...