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AbstractThis study aimed to understand the impact of computer-mediated communication (CMC) tools on journalism in Vietnam by employing a quantitative-methods approach influenced by Social Presence Theory, Media Richness Theory, and Uses and Gratifications Theory. A quantitative survey was conducted with 335 journalists and other stakeholders in newsrooms. The results indicated that social presence significantly affects the adoption and efficacy of CMC tools in this unique cultural context. The study extended the Media Richness Theory by adding a cross-cultural dimension, and the Uses and Gratifications Theory sheds light on the motivations behind tool adoption. This research contributed to theory by adapting established frameworks to a new cultural environment and offers practical guidelines for media organizations in Vietnam undergoing digital transformation. Future research should explore interdisciplinary frameworks incorporating cultural, technological, and psychological factors.

AbstractConstruction of industrial enterprises has become more necessary in recent years. It is critical for project managers to estimate the entire cost of a building project at this early stage. Existing approaches that use operator experience as a mathematical formula. Initial estimates are inaccurate due to the lack of available data points, which leads to overruns in project costs. This research utilizes different machine learning techniques to predict preliminary factory construction cost. Five popular numeric predictive techniques: support vector machine (SVM), artificial neural network (ANN), generalized linear regression (GENLIN), classification and regression-based techniques (CART), exhaustive chi-squared automatic interaction detection (CHAID) are used for baseline and ensemble models. A deep learning neural network (DLNN) is also utilized in this study. The machine learning model is trained and tested on actual data gathered in the southern part of Vietnam. Deep learning outperforms all other machine learning algorithms in this comparison, while the ensemble model of artificial neural networks and generalised linear regression also fared well. Cost estimators can quickly pick the best model for projecting the cost of constructing a preliminary factory by having access to a variety of estimate methodologies.

As initial endeavors, this paper presents an in-depth study to investigate the influence of nanoscale parameters on bending and free vibration responses of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) nanoshells with double curvature. Carbon nanotubes (CNTs) are considered as reinforcements that are distributed across the shell thickness with two different distributions, namely the UD and FG-X. First of all, the mathematical formulas are built on the nonlocal strain gradient theory which, as a critical point of this study, considers both nonlocal and strain gradient parameters simultaneously. Additionally, toward using the Navier solution, the simply supported boundary condition is established to obtain the deflection and natural frequency of FG-CNTRC nanoshells. Furthermore, some specific numerical results are shown and compared with the results reported in the literature. Most importantly, the new findings are given and discussed deeply to show the effect of nanoscale parameters and material property and shape of shells on the deflection and fundamental frequency parameters of the FG-CNTRC nanoshells. From the obtained results, it is shown that the small length-scale has a significant effect on frequencies and deflection of FG-CNTRC nanoshells.

One‐pot reactions of pyridine‐ or catechol‐scaffolding aroylbis(N,N‐diethylthioureas), H2L1or H2L2, with methanolic solutions of FeCl3and NH4Cl bring about novel cationic ammonium‐inclusion complexes {NH4⊂ [Fe2(L)3]}+(L = L1or L2), which could be separated as PF6–salts. The inclusion compounds have been characterized by elemental analyses and spectroscopic methods such as HRMS, IR and SCXRD. Ammonium ions are captured in the intramolecular voids of {2}‐metallacryptands {[Fe2(L)3]} (L = L1or L2) resulting from the octahedral coordination of Fe3+ions with aroylthiourea moieties of the ligands. Hydrogen bonds are established between the NH4+ions and the donor atoms of the cages.

The new ligand N‐methylanthraniloyl(4‐ethylthiosemicarbazide) H2L was synthesized by the treatment of anthranilic acid hydrazide and ethyl isothiocyanate in absolute ethanol. The composition and structure of H2L were characterized by spectroscopic methods such as ESI MS, IR, 1H and 13C{1H} NMR spectroscopy as well as SCXRD. Reaction of H2L and mixture of [Cu(MeCN)4](PF6) and o‐phenanthroline in methanol gave rise to a cationic Cu(II) trinuclear complex, which could be separated as PF6–salt with the composition of [Cu3(L)2(o‐phen)2](PF6)2. The spectroscopic and X‐ray crystallographic data analyses demonstrated that H2L deprotonates hydrazide protons and the resulting dianion {L2–} acts as bridging ligand of which most potential donor atoms form stable chelates with Cu(II) ions. In particular, the central Cu(II) ion coordinates with two dianions {L2–} via (O, N2) donor sets, thereby adopting a distorted square planar coordination mode with transconfiguration. While each of two terminal Cu(II) ions is five‐coordinate with the coordination sphere composed of (S, N1, Namine) and (N,N) donor sets belonging {L2–} and o‐phenanthroline, respectively.

The study and manufacture of functionally graded (FG) shallow shells with the variable thickness are essential for the actual application of these types of structures. Previously, many researchers have developed different approaches to analyzing the mechanical behaviors of the FG structures, in which the thickness parameter has been assumed to be constant. Moreover, studies on these types of structures with the variable thickness are still quite limited. For this reason, this paper provides an effective and simple approach via mathematical formulations for analyzing the free vibrational responses of FG shallow shells with the variable thickness. Also, the presence of porosities that can occur during the fabrication of FG materials is considered. One of the highlights here is to consider the influence of the physical neutral surface. Before conducting the analysis of these FG structures, firstly, it is important to establish governing equations based on the classical shell theory. These essential equations are used for the FG shallow shells. Then, by setting the Navier solution with the help of simply supported boundary conditions, the natural frequencies are obtained. Finally, the numerical examples will be given to illustrate the effects of porosity coefficient, material and geometry parameters as well as the physical neutral surface on the natural frequencies. In addition, two numerical examples for verification will also be performed and thereby show the accuracy of the current method and model. It is hoped that the main results of this study can be useful not only to designers and researchers but also to be extended to more complex problems.

This paper deals with geometrically nonlinear buckling analysis of functionally graded carbon nanotube reinforced (FG-CNTR) cylindrical panels. The FG-CNTR cylindrical panel is assumed to be rested on the Winkler–Pasternak elastic foundation and subjected to uniform pressure. In the FG-CNTR cylindrical panel model, uniform and three distributions of carbon nanotubes, which are graded in the thickness direction of the panel, are considered. Effective properties of materials of the panels reinforced by single-walled carbon nanotubes are estimated through a micromechanical model based on the extended rule of mixtures. Governing equilibrium equations of the FG-CNTRC cylindrical panel are obtained based on the classical shell theory and considering the von Karman geometrically nonlinearity and initial geometric imperfection. A closed form of the resulting stability equations is established via the Galekin procedure to obtain the buckling load–deflection relations in case of simply supported boundary condition. In the numerical results section, the exactness of formulation is validated by comparing the obtained results with those reported in the open database. Then, a comprehensive investigation into the influence of carbon nanotube volume fraction, carbon nanotube distribution rule, imperfection parameter, elastic foundation as well as the geometry parameters on the nonlinear buckling behaviors of the FG-CNTRC cylindrical panels is discussed in detail.

The Shubnikov – de Haas magnetoresistance oscillations in the Quantum well (QW) under the influence of confined acoustic phonons, The theoretical results show that the conductivity tensor, the complex magnetic impedance of the magnetic field, the frequency, the amplitude of the laser radiation, the QW width, the temperature of the system and especially the quantum index m characterizes the confinement of the phonon. The amplitude of the oscillations of the Shubnikov-de Haas impedance decreases with the increase of the influence of the confined acoustic phonons. The results for bulk phonons in a QW could be achieved, when m goes to zero. We has been compared with other studies when perform the numerical calculations are also achieved for the GaAs/AlGaAs in the QW. Results show that The Shubnikov-de Haas magnetoresistance oscillations amplitude decrease when phonon confinement effect increasing and when width L of the QW increases to a certain value, The Shubnikov – de Haas magnetoresistance oscillations amplitude completely disappears can not be observed.

Macaranga balansaeGagnep., locally known as “Ba soi lông tơ” or “Mã rạng balansa”, is a tree endemic to Vietnam, found at central provinces. Its ethyl acetate extract was showed cytotoxic activity against TG1 cancer cell line. In this paper, we report the preliminary study on the chemical constituents of the leaves of M. balansae. Seven known compounds including lupeol (1), phytol (2), isophytol (3), sitostenone (4), sitoindoside I (5), gallic acid (6) and methyl gallate (7) were isolated from the ethyl acetate extract of the leaves of M. balansae. Their chemical structures were identified by NMR, MS spectra and in comparison with the reported literatures.

The genus Macaranga, one of the largest genera of the Euphorbiaceae family has approximately 300 species distributed in the tropical regions. Plants of this genus displayed various bioactivities such as antioxidant, antitumor and antimicrobial effects. Macaranga balansaeGagnep. is an endemic plant in Vietnam, that ethyl acetate extract showed cytotoxicity to cancer cell line. In this article, we report the isolation and structural elucidation of six known compounds from the ethyl acetate extract including (‐)‐dehydroxycubebin (1), trans‐coniferyl aldehyde (2), 3,3',4'‐tri‐O‐methyl ellagic acid (3), stigmastane 3β,5α,6β‐triol (4), 2,3‐dihydroxy‐1‐(4’‐hydroxy‐3’‐methoxyphenyl) propan‐1‐one (5), and protocatechuic acid (6). To the best of our knowledge, compounds 1‐5were isolated from Macarangagenus for the first time.

In this study, the metallic-Ag@ferromagnetic-Fe3O4nanoparticles has been used as a promising spintronics material to gain deeper insights into spintronics-related electrochemical reactions under the influence of an applied external magnetic field (MF) including spin polarization, spin transport, and spin selectivity. Ferrocyanide/ferricyanide ([Fe(CN)6]3‒/4‒), paracetamol (PCM), and chloramphenicol (CAP) were chosen as the suitable reactants for one-electron transfer reversible redox reaction, two-electron transfer quasireversible redox reaction, and four-electron transfer irreversible reaction at Ag@Fe3O4modified electrodes, respectively. By using an external MF-assisted electrochemical platform and magneto-plasmonic Ag@Fe3O4electrode to trigger spin polarizing, spin transporting, and spin selectivity effects in electrode reactions, the selective enhancement of the electro-reduction reaction in comparison with electro-oxidation reaction has been elucidated. The obtained experimental data along with calculated electrochemical kinetic parameters indicate that an applied external MF affects the electrochemical kinetics (electron transfer kinetics, electrocatalytic activity, and adsorption/diffusion capacity) of the one-, two-, and four-electron transfer processes in different ways. Considering the pronounced effects of magnetic field on overall electrochemical performance and intrinsic advantages of spintronics enhanced the electro-reduction reaction, these developed techniques could provide innovative strategies for the development of novel spin-dependent electrochemical sensing approaches.

In this study, the preparation of core/shell Ag@Fe3O4nanoparticles (NPs) and its potential application toward highly sensitive electrochemical detection of furazolidone (FZD) have been reported. UV–visible spectroscopy, X-ray diffraction, scanning electron microscopy, and Zeta sizer are systematically carried out to confirm the formation, size distribution, and composition of Ag@Fe3O4NPs. By computing the electrochemical characteristic parameters such as electrochemically active surface area (ECSA), electron-transfer resistance (Rct), standard heterogeneous rate constant (k0), adsorption capacity (Γ), and electron transfer rate constant (ks), the Ag@Fe3O4-modified electrode possessed remarkably enhanced electrochemical sensing performance for FZD determination compared to the unmodified screen-printed electrode (SPE). This enhancement of electrochemical activity can be attributed to the fast electron transfer kinetics and great adsorption capacity that arise from the synergistic coupling between the good electrical conductivity of the core AgNPs and the porosity of the protective Fe3O4shell. Under optimum conditions, the Ag@Fe3O4-based electrochemical nanosensor exhibited not only high sensitivity toward FZD detection of 1.36 μA μM−1cm−2in the linear ranges from 0.5–15 μM and 15–100 μM, and low detection limit of 0.24 μM but also long-term stability, repeatability, and anti-interference ability. The applicability of the proposed sensing platform in honey and milk samples was also investigated.

The recent advancement in designing novel spinel nanostructures has opened virtually infinite possibilities for the development of high-performance electrochemical sensors to detect target species. The electrocatalytic activity of spinel structures can be enhanced by tuning the cation distribution; however, the role of cation distribution at tetrahedral ions on the electrochemical sensing responses has rarely been considered. Herein, the effect of cation distribution at tetrahedral sites (Td) in the spinel nanostructure ZnCo2O4on the electrochemical sensing performance toward carbaryl (CBR) was first investigated. The ZnCo2O4nanoflake samples with different cation ratios of Zn/Co at tetrahedral sites were designed by using a facile solvothermal method. We found that a higher Zn ion content at tetrahedral sites significantly enhanced the electron transfer ability through the electrolyte/electrode interface. More interestingly, a higher Co ion ratio between octahedral sites and tetrahedral (CoOh/CoTd) promoted the electrochemical oxidation process of CBR with a higher catalytic rate constant (kcat). Under optimized conditions, the ZnCo2O4-NF-based electrochemical nanosensor showed a linear response from 0.15 to 100 μM with a limit of detection of 0.05 μM and a high electrochemical sensitivity of 2.04 μA μM–1cm–2. The designed nanosensor also exhibited good repeatability, long-time stability, high anti-interference ability, and excellent recovery with fruit and vegetable samples. Furthermore, this study offers insights into the cation distribution-dependent electrocatalytic activities of spinel nanostructures, which is helpful to the design of advanced spinel nanostructure-based electrocatalysts for improving the electrochemical sensing performance.

In this study, graphene-carbon nanotube (CNT) hybrid films were directly synthesized on polycrystalline copper (Cu) substrates by thermal chemical vapor deposition (CVD) method. Graphene films were synthesized on Cu substrate at 1000 °C in mixture of gases: argon (Ar), hydrogen (H 2 ), and methane (CH 4 ). Then, carbon nanotubes (CNTs) were grown uniformly on the surface of graphene/Cu films at 750 °C in mixture of Ar, H 2 , and acetylene (C 2 H 2 ) gases. Ferric salt FeCl 3 solution deposited onto the surface of graphene/Cu substrate by spin coating method was used as precursor for the growth of the CNTs. The density and quality of the CNTs on the surface of graphene/Cu films can be controlled by varying the concentration of FeCl 3 salt catalyst. [ABSTRACT FROM AUTHOR]

In this work, we investigated the effect of morphology on the analytical performance of α-Fe2O3nanostructures-based electrochemical sensors toward chloramphenicol (CAP) antibiotic using three designed morphologies including α-Fe2O3nano-tube (α-Fe2O3-T), α-Fe2O3nano-rice (α-Fe2O3-R), and α-Fe2O3nano-plate (α-Fe2O3-P). Among these morphologies, α-Fe2O3-T displayed an outstanding electrochemical activity owing to the unique hollow structure and large specific surface area. However, due to the small pores size, α-Fe2O3-T showed the high steric hindrance (SD) effect towards an antibiotic with complex molecular structure, as CAP, leading to a significant decrease of their CAP electrochemical sensing performance. The CAP analytical performance of α-Fe2O3-R was highest in investigated morphologies owing to a high density of exposed Fe3+as well as less SD effect towards CAP molecules. Under optimized conditions, α-Fe2O3-R-based CAP electrochemical sensor reached an electrochemical sensitivity of 0.92 μA μM−1cm−2with a LOD of 0.11 μM in the detection range from 2.5–50 μM. In addition, all these α-Fe2O3nanostructures-based electrochemical sensors had excellent stability and high anti-interference ability for CAP analysis in a complex food matrix, as shrimp sample. This study provides valuable insights into the morphology-dependent sensing properties of α-Fe2O3nanostructures towards antibiotics, which is helpful to the design of novel α-Fe2O3-based electrochemical nanosensors.

In this work, we study the magnetic properties of a CoFe/NiFe/PZT heterostructured nanocomposite that is affected by the strain in the PZT substrate when a voltage in the range from −250 to 250 V is applied. An interesting electric-voltage-controlled magnetic anisotropy, with a relative increase in magnetization up to above 100%, is observed. This brings a new challenge to operate a low-power-consuming spin electronic device. We also utilize a theoretical model based on interfacecharge-mediated and strain-mediated magnetic-electric coupling to understand the change in the magnetic properties of the investigated material.

Decreased memory B-cell maintenance during HIV-1 infection has been associated with the viraemia-induced accumulation of activated memory B cells, sensitive to Fas-mediated apoptosis. We aimed at clarifying whether other B-cell subsets might also be affected by an increased Fas expression in HIV-1-infected patients, and we studied the possible contribution of viraemia, lymphopenia or T-cell activation in Fas upregulation on B cells. We analysed whether Fas upregulation might have collaborative effects with the dysregulation of other B-cell modulatory molecules, leukocyte-associated immunoglobulin-like receptor 1 (LAIR1) and programmed cell death protein 1 (PD-1), on B-cell homeostasis.

Background In countries where antiretroviral therapy has been available or is being rapidly expanded, the World Health Organization (WHO) recommends surveillance for transmitted HIV drug resistance (HIVDR) by threshold surveillance methods using specimens from antenatal clinics or voluntary counselling and testing (VCT) sites. The aim of this study was to implement the HIVDR threshold survey in VCT sites in Vietnam, where HIV prevalence is high. Estimating transmitted resistance in the infected population will enable the appropriateness of current antiretroviral drug regimens to be assessed and will inform plans for future HIVDR surveillance.Methods Consecutive blood specimens were collected from 70 newly diagnosed HIV-positive clients 18–24 years of age at two sites in Hanoi, Vietnam. Informed consent and serum specimens were obtained from each eligible client, with serum frozen at -70°C until shipping to Thailand for resistance testing using the TruGene system.Results From February until August 2006, 559 clients were eligible to participate in this survey. Of the 535 clients (95.7%) who agreed to participate, 70 (13%) were HIV-positive and were included in the survey. Of the 70 specimens sent for genotyping, 52 consecutive samples were amplified, 49 of which could be genotyped. Only 1 of 49 genotyped specimens had mutations associated with drug resistance (L74V and Y181C) in the reverse transcriptase gene, indicating that the prevalence of transmitted HIVDR to all drugs and drug classes evaluated was <5%.Conclusion The prevalence of transmitted HIVDR was low in Hanoi as determined using threshold surveillance methods. The Ministry of Health plans to repeat this survey methodology in one more province and to confirm these findings by expanded HIVDR surveillance.

To investigate the nature of recent HIV outbreaks among injecting drug users (IDUs) near the Vietnam-China border, we genetically analyzed 24 HIV-positive blood specimens from 2 northern provinces of Vietnam (Lang Son and quang Ninh) adjacent to the China border, where HIV outbreaks among IDUs were first detected in late 1996. Genetic subtyping based on gag (p17) and env (C2/V3) sequences revealed that CRF01_AE is a principal strain circulating throughout Vietnam, including the provinces near the China border. The majority of CRF01_AE sequences among IDUs in Quang Ninh and Lang Son showed significant clustering with those found in nearby Pingxiang City of China's Guangxi Province, sharing a unique valine substitution 12 amino acids downstream of the V3 loop. This particular subtype E variant, uniquely found among IDUs in northern Vietnam and southeastern China, is designated Ev. The genetic diversity of CRF01_AE distributed in Quang Ninh (1.5 ± 0.6%) and Pingxiang City (1.9 ± 1.2%) was remarkably low, indicating the emerging nature of HIV spread in these areas. It is also noted that the genetic diversity of CRF01_AE among IDUs was consistently lower than that in persons infected sexually, suggesting that fewer closely related CRF01_AE variants were introduced into IDUs and, conversely, that multiple strains of CRF01_AE had been introduced via the sexual route. The data in the present study provide additional evidence that HIV outbreaks among IDUs in northern Vietnam were caused by the recent introduction of a highly homogeneous CRF01_AE variant (Ev) closely related to that prevailing in nearby southern China.

Based on the variational principle, equations and boundary conditions for transverse steady vibrations of a bimorph consisting of a piezoelectric and piezomagnetic layers are obtained. The results of calculations of natural frequencies are compared with the finite element model of the device in ACELAN.

A study of the chemical constituents of a methanolic extract of the roots of Livistona halongensis(Arecaceae) led to the isolation of two new flavanes, 2S,3S-3,5,7,3'-tetrahydroxy-5'-methoxyflavane (1) and 3,7,3'-trihydroxy-5'-methoxyflavane 5-O-β-glucopyranoside (2), together with trans-3,5,3',5'-tetrahydroxy-4-methoxystilbene, saccharose and β-sitosterol-3-O-β-glucopyranoside. The structures of these compounds were elucidated on the basis of spectroscopic data.

Recently, the electric field induced manipulation of magnetic properties has become one of the most interesting research topics because of its promising applications in magnetoelectronics, such as future logic elements and electric-magnetic memories. In this paper, the NiFe/CoFe ferromagnetic nanostructured thin films were directly deposited on the ferroelectric PZT substrate, which was polarized parallel to the thickness or along the surface. In these samples, the stress originating from the piezoelectric layer is transferred into the magnetostrictive layer, which induces an elastic strain and results in a change in magnetization, thanks to the converse magnetoelectric effect. By analyzing the magnetization of the nanocomposite under a fixed magnetic field up to 5×103?Oe at different voltages applied to the ferromagnetic substrate, we can investigate the voltage-controllable magnetization in this composite. The obtained results show that the magnetization of the NiFe/CoFe film changes around 6% at the low voltage of 60?V and up to two times larger at 800?V in an external magnetic field of 50?Oe. The use of voltage also allows the reversible adjustment of the magnetization orientation in ferromagnetic layers.