Vinh University

The study aims to examine the factors affecting the satisfaction and loyalty of foreign investors in a locality through ‘hard’ infrastructure and ‘soft’ infrastructure factors. The author used Cronbach’s Alpha, EFA, and SEM to analyze primary data and test the hypothesis. The findings indicate that factors such as Infrastructure, Human Resources, Investment Policy, Living Environment, Local Brand, Quality of Public Services, and Local Advantages impact FDI investors’ satisfaction. Meanwhile, Competitive input costs are the only factor affecting the loyalty of FDI investors which differs from previous research. These results serve as a crucial foundation for Vietnamese municipalities to implement various strategies to enhance satisfaction and bolster the loyalty of FDI investors, ultimately amplifying the draw of foreign direct investment into the area.

Eight furostanol glycosides including five undescribed compounds, named tribufurostanosides A‐E (1‐5), and three known ones (6‐8) were isolated from the fruits of Tribulus terrestris L. Their chemical structures were determined by the IR, HR‐ESI‐MS, 1D‐, and 2D‐NMR spectra. Furostanols 1‐8 significantly inhibited nitric oxide production in LPS activated RAW 264.7 cells with IC50 values ranging from 14.2 to 64.7 µM, compared to that of the positive control compound, dexamethazone (IC50 13.6 µM).

This article is to provide the findings of a study on the optimization of plasma nitriding technology parameters for a hypoid gear working surface made of SAE 5120 material. The experiment of the nitriding was conducted in an Eltropuls H045 × 080 plasma nitriding device. The second-order planning with 27 experiments was implemented, varying the permeation time (h), the permeation temperature (TL), and the gas permeation concentration (G1). From the experiment, the set of optimized input parameters was derived: permeation time: 6.14 h; permeation time: 533.8 h; and gas permeation concentration: 5.7 l/h. The finding revealed that the temperature has a positive influence on all three parameters: hardness, thermal deformation, and roughness, but the roughness tends to slightly decrease. The concentration (flow rate) of the gas mixture has the weakest impact on the parameters, except for thermal deformation. This process is recommended for heat treating the gear box made of SAE 5120 steel.

A multifunction forest firefighting automotive is a piece of specialized equipment manufactured to solve the problem of a lack of firefighting automotives in Vietnam. When installing specialized equipment for firefighting, the load on the automotive increases, affecting the durability of the details. Meanwhile, the axle housing is an important part of the powertrain, storing all the main parts for transmission, such as the differential and semi-axle. Simultaneously, the axle housing performs the function of a beam, which bears the weight of the body and must be affected by loads from the relationship between the automotive’s wheels and the pavement. When the automotive is operating under the impact of the road surface, it will generate a dynamic bead impact on the axle housing. This paper gives findings from studies that examined the impact of automotive speed on the dynamic beam impact on the drive axle housing cover of a multifunction forest firefighting automotive. In this paper, the author establishes a system of vehicle dynamics equations utilizing the multi-body system and Newton–Euler methods. The dynamic load of vehicles on a straight road with road surface profiles is surveyed using Matlab-Simulink software in accordance with ISO 8608:2016. The research results have determined the greatest load acting on the axle housing as the automotive is in motion on a bumpy road and the dynamic load over time in accordance with ISO 8608:2016 while the automotive is in motion on the road. In accordance with ISO 8608:2016 specifications, the dynamic load factor of a vehicle traveling along an uneven road has not surpassed the permissible threshold. However, in the presence of road obstacles measuring 0.3 m or more in height, the vehicle’s speed must not exceed 15 km/h, this has an effect on the efficacy of forest firefighting in Vietnam due to the extremely irregular forest terrain.

The discovery and development of novel contrast agents for CT imaging could address the current limitations of this non-invasive testing technique, thus improving diagnostic efficiency. Although this approach is significant to clinical research, finding a highly potent and biocompatible contrast agent is challenging. In our study, the homogeneous and monodisperse Au nanospheres were successfully synthesized using chemical reduction. The influence of surfactants, oleylamine (OLA) and sodium oleate (SOA); solvent; and reaction time on the materials’ formation, size, and properties was examined to find the optimal conditions. Investigation showed that using OLA and SOA as surfactants resulted in materials with similar morphology and uniformity. The solvent 1-octadecene (ODE) and reaction time in the 30–60-min range facilitated the formation of uniform and monodisperse gold nanoparticles (GNPs). Characterization indicated that the fabricated Au materials were crystalline and spherical with a face-centered cubic (fcc) structure and an average size of 8.4–20.7 nm. Their maximum surface plasmon resonance (SPR) absorbance varied in the range of 516–531 nm. After surface modification by the poly(maleic anhydride-alt-1-octadecene) (PMAO), the Au NPs were highly stable in a aqueous solution with a zeta potential ranging from − 45.6 to − 42 mV, dynamic light scattering (DLS) size of 17.7 and 26.8 corresponding to the sample size of 8.4 nm and 15.5 nm, respectively. In vitro CT imaging results show that the material Au@PMAO enhanced the CT image contrast signals. Particularly, the smaller GNPs exhibited higher X-ray attenuation than the large ones. At the same investigated concentration, the image contrast performance of the Au@PMAO NPs outweighed that of the commercial product Xenetix, which contained iodine. These outstanding properties prove that the Au@PMAO material is a promising alternative for CT imaging techniques.

Objective/Background: In Chinese, Vietnamese, and Thai traditional medicine of Southeast Asian countries, Stemonaceae plants have long been employed. Various studies have proved that these herbal plants contain Stemona alkaloids with valuable medicinal value. Although some review articles on Stemona alkaloids have appeared in the literature, they are quite outdated. The current study offers a comprehensive review of the isolation and bioactivities of Stemona alkaloids. The article might be useful for chemists who work in alkaloid chemistry as well as pharmaceutical areas. Methods: “Stemona alkaloids” was the most useful keyword to search for literature data. References have been collected from various resources such as Google Scholar, SciFinder, and PubMed. More than 120 electronic publications were obtained from these resources. Results: More than 250 Stemona alkaloids from 8 groups have been isolated and structurally elucidated from Stemonaceae plants. Extracts from these plants as well as isolated compounds possess a wide range of bioactivities, such as antituberculosis, antibacterial, antifungal, and antihelmintic properties activities. Conclusion: In this review article, we have summarized 116 studies on the isolation and bioactivities of Stemona alkaloids in the literature. More than 250 Stemona alkaloid compounds have been isolated and identified. In addition, the article also gives an overview of the bioactivities of Stemona alkaloids.

Scientists from a variety of disciplines have recognized social capital as a valuable resource in Vietnam since the early 2000s; nevertheless, this kind of capital can only exist when it is observable and the benefits of social capital can be quantified (Uphoff & Wijayaratna, 2000). As seen by the poor engagement in social activities and social media networks, social capital is actually very restricted in Vietnam’s state general education schools. This makes it difficult to raise the standard of instruction and learning objectives. This study aims to investigate the influence of social capital on the advancement of public general education. By analyzing the structural equation model (SEM), the study’s survey method uses a questionnaire with a scale of 488 teachers and employees in public general education. As shown in the result, social capital impacts not only directly and positively but also indirectly on the development of public general education through intermediary factors such as in-school knowledge transfer, school brand, and training service quality. The study makes several recommendations to increase social capital in order to set the groundwork for the growth of public general education in Vietnamese schools, based on these findings.

Objective/Background: Zingiber monophyllum Gagnep., a member of the Zingiberaceae family, is known for its significant biological activities. The current study aimed to determine the volatile components of the ethyl acetate (EtOAc) fractionated extract found in the rhizomes of this species. This is the first report on the chemical composition and bioactivities of Z. monophyllum rhizomes fractionated extract. Methods: The chemical constituents were analyzed and determined using gas chromatography-mass spectrometry (GC-MS). Antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays using ascorbic acid as a positive control. Antibacterial and antifungal properties of the EtOAc fractionated extract of Z. monophyllum rhizomes were assessed against Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, and Candida albicans. Density functional theory (DFT) and molecular docking were also employed to illustrate antioxidant and antimicrobial activities. Results: Nine components were identified by GC-MS analysis from the EtOAc fractionated extract of Z. monophyllum rhizomes. (E)-labda-8(17),12-diene-15,16-dial (9), spathulenol (2), and neointermedeol (5) were the major components (21.8%, 16.8%, and 11.9%, respectively). Moderate antioxidant activities of the EtOAc fractionated extract were observed via both the DPPH assay and the FRAP assay using ascorbic acid as the standard compound. The extract demonstrated remarkable antimicrobial activity against all examined microbial strains, except for P. aeruginosa. The DFT study analyzed the antioxidant potential of each component in the fractionated extract. Molecular docking study chose E. faecalis DNA gyrase B, E. coli DNA gyrase B, S. aureus biotin protein ligase, E. faecalis Alanine racemase, and C. albicans N-myristoyltransferase as potential target proteins for antimicrobial activity. Conclusion: In this study, the chemical composition of the EtOAc fractionated extract of Z monophyllum rhizomes was demonstrated through GC-MS analysis for the first time. Nine components, including alloaromadendrene, spathulenol, globulol, τ-cadinol, neointermedeol, aromadendrene oxide-(2), ambrial, (E)-15,16-dinorlabda-8(17),11-dien-13-one, and (E)-lambda-8 (17),12-diene-15,16-dial along with relative content were identified in this fractionated extract. The bioassays revealed that the fractionated extract showed moderate antioxidant activities and significant antimicrobial activities. The antioxidant and antimicrobial potential of each component was also theoretically examined by the DFT study and molecular docking study, respectively.

This study investigates the buckling and free vibration behavior of functionally graded saturated porous (FGSP) using a refined quasi-3D theory that ensures zero transverse shear stress at the top and bottom surfaces of the plate. The material properties depend on the porosity coefficient according to three patterns. Hamilton's principle and Biot's poroelasticity theory are employed to derive the equations of motion, which are then solved using Navier's technique. After examining the accuracy of the suggested approach, the effect of fluid compressibility on natural frequency and critical buckling load is investigated in the undrained condition. Also, the effect of porosity, geometrical parameters, and elastic foundation on the vibration and buckling response of FGSP plates are examined. The study reveals that saturating the pores with fluid leads to increased plate stiffness. This translates to higher critical buckling loads and fundamental frequencies.

In this work, the CdS/CdSe multi-layers were coated on the ZnS:Cu²⁺ passivation layer to reduce the dark current density and enhance the photon absorption intensity. The passivation layer was fabricated using the SILAR method with different Cu/Zn atom ratios of 0%, 0.1%, 0.3%, 0.5%, 0.7%, and 1.0%, respectively. The photoanode was structurally characterized by XRD and FESEM equipment. It was also studied for optical properties by UV–Vis spectroscopy and electrochemical properties by J-V curves, and electrochemical impedance spectra. As a result, there is a shift peak in the absorption spectrum in the visible light region of films when Cu²⁺ ions were doped on the pure ZnS film. Furthermore, this result was also demonstrated when quantum dot-sensitized solar cells were recorded using the J-V curves. The performance of all cells containing ZnS:Cu²⁺ has a higher current density (JSC ~ 18.11 mA cm⁻²–22.05 mA cm⁻²) than the photoanode with pure ZnS (JSC ~ 16.85 mA cm⁻²). The results show an increase in the conversion efficiency of the cell because of reducing excited electrons from CdS/CdSe quantum dots to the polysulfide electrolyte, the appearance of Cu²⁺ energy levels in the band gap of ZnS causes an increase in photon absorption. In addition, the values of dynamic resistance Rct1 and Rct2 were determined from the electrochemical impedance spectrum are the smallest (11.88 Ω, and 115.56 Ω) at a doping concentration of 0.5%. It shows that excited electrons move easily and reduce recombination processes in the photoanode.

Chemical compositions in the leaf essential oils of four Syzygium species were first identified by the GC-FID/MS analysis. Monoterpene hydrocarbons (39.6-51.1%), and sesquiterpene hydrocarbons (27.0-37.8%) were the main chemical classes in S. formosum and S. syzygioides leaf oils, whereas sesquiterpene hydrocarbons (83.0-83.8%) were predominant in S. Megacarpum and S. chantara-nothaianum leaf essential oils. Bicyclogermacrene (9.1-37.0%) was the principal compounds in these essential oils. All the tested essential oils with the MIC values of 16-128 µg/mL were comparable to the positive control streptomycin against Gram-positive bacteria Staphylococcus aureus and Bacillus cereus, and Gram-negative bacterium Pseudomonas aeruginosa. The leaf essential oils of S. formosum, S. syzygioides, and S. chantaranothaianum with the MIC values of 16-128 µg/ mL were comparable to the positive control cycloheximide against the yeast Candida albicans. Four samples also exhibited good larvicidal activity against the mosquito Aedes aegypti with the 24-h and 28-h LC 50 values of 25-40 µg/mL ARTICLE HISTORY

The investigation of Nida Valley water aimed to assess fluctuations in physicochemical properties. In this study, environmental monitoring method was utilized to evaluate the changes in physicochemical properties of water. Over a 24-month period, from June 2021 to May 2023, a total of 228 water samples were collected from 10 sampling sites, with a monthly sampling frequency. Statistical analyses were utilized including the Shapiro–Wilk test (α = 0.05), Kruskal–Wallis test and Wilcoxon (Mann–Whitney) rank sum test (α = 0.05), Pearson correlation analysis (α = 0.001) and principal component analysis (PCA). Statistical analyses revealed significant differences between months in GW samples for for temperature, dissolved oxygen, pH, total nitrogen, total phosphorus, chloride, manganese, and zinc in GW samples and for T and DO in SW samples. Pearson correlation coefficient analysis (α = 0.001) identified strong positive correlations within the SW dataset. Similarly, significant positive correlations were observed among the GW dataset. Noteworthy positive correlations were also detected between the GW and SW datasets. Principal component analysis (PCA) revealed a substantial dissimilarity between GW2 samples compared to others, characterized by elevated manganese, iron, and Sulfate content. Two distinct groups emerged: Group 1 included samples at GW1, GW2, GW3, GW5, and SW2, while Group 2 comprised all other samples. This study demonstrated the stability in the physicochemical properties of SW and underscore a discernible correlation between the hydrochemical compositions of both SW and GW in the riparian area. Outstanding characteristics in hydrochemical component of sample waters have been indicated.

Thermophoresis and diffusiophoresis or the directional motion of particles in liquids and gases driven by a temperature and concentration gradients. These phenomena are of both fundamental interest and practical use. So far, thermophoresis, diffusiophoresis along with their dynamics have been investigated and applied. In this paper, a type of thermodynamic force is studied and applied to explain the thermophoresis processes in gases. This force is known as the general thermophoretic force driven by both the temperature and the concentration gradients. It is caused by elastic collision between gas molecules and particles suspended in the gases. The results show that: (i) Based on the kinetic theory of gases, the equation describes the general thermophoretic force can be derived. (ii) Both the thermophoretic force (which is driven solely by a temperature gradient) and the diffusiophoretic force (which is driven solely by a concentration gradient) are special cases of the general thermophoretic force. (iii) Both the thermophoretic and the diffusiophoretic forces depend on the size of gas molecules and particles. (iv) The general thermophoretic force can be applied to explain the thermophoresis: the negative thermophoresis (negative Soret effect) can occur when the diffusiophoretic force opposes the thermophoretic force. (v) The Soret coefficient can be determined by the balanced state of the general thermophoretic force. (vi) The thermophoretic force and diffusiophoretic force of the gases exerted on gas molecules are not depended on the size of molecules. (vii) Under the normal condition (temperature is 20 °C and the pressure is 1 atm), the thermophoretic force and the diffusiophoretic force exerted on gas molecules are approximately 2.45 × 10–24 N and 1.74 × 10–24 N respectively.

The effectiveness of an organization is significantly influenced by the leadership styles used (Almahasneh et al., 2023). This study aims to investigate how the emotional intelligence (EI) of managers affects transformational leadership styles in North Central Vietnamese enterprises. With data from 632 samples — managers — exploratory factor analysis (EFA) and structural equation modeling (SEM) were used to define the study problem using the quantitative approach. The findings demonstrate that through the intermediary components of employee knowledge sharing at work and corporate social responsibility, managers’ EI has both direct and indirect impacts on transformational leadership style. Furthermore, information sharing has been shown to have a positive impact on corporate social responsibility toward employees and a negative impact on opportunistic behavior. Based on the findings, several recommendations are proposed to enhance and promote the effectiveness of transformational leadership styles for managers. Considering the social implications and the practicality of the research, stakeholders should push for solutions that would ensure transformational leadership styles for managers. The study’s findings contribute to our understanding of leadership and are particularly useful for teams working in Vietnamese and other Asian firms.

Objective/Background: Camellia L., belonging to the Theaceae family, is a diverse group of plant species native to various regions of Asia. Methods: Chlorophyll and carotenoid contents in leaves of three Camellia species, namely Camellia quephongensis, Camellia yokdonensis, and Camellia longii, were determined using a spectrophotometric method. Phenolic compounds of the leaf extracts were quantified using high-performance liquid chromatography. Additionally, antioxidant activity, anti-α-amylase and in vitro antiinflammatory properties of the extracts were evaluated. Results: The total carotenoid content in C. longii was the highest, whereas the total chlorophyll content in this species was the lowest. Most of the phenolic compounds in C. quephongensis were found at the greatest concentrations compared to the other species. The extract from C. quephongensis exhibited the strongest antioxidant properties estimated by ABTS and DPPH free radical scavenging assays. This activity was shown to be comparable with that of ascorbic acid. All the Camellia extracts may possess a much less potent anti-α-amylase activity in comparison with acarbose. They could also be weaker than diclofenac with respect to in vitro anti-inflammatory activity evaluated by albumin denaturation inhibition assay. Conclusions: The findings of this investigation provide the initial insights into pigments and phenolics present in the various Camellia species and pave the way for the development of functional foods that could potentially offer a range of health benefits.

This study attempted to improve the photocatalytic activity of zinc oxide (ZnO) semiconductors in the visible light region by introducing the co-doping of carbon (C) and tantalum (Ta) to ZnO (ZTC) using a simple hydrothermal method with the respective precursors. The obtained uniform ZTC nanoparticles with an average crystal size of 29.30 nm (according to Scherrer's equation) revealed a redshift with a decrease in bandgap (Eg) from 3.04 eV to 2.88 eV, allowing the obtained photocatalyst to absorb the energy of the visible light for photocatalysis. Furthermore, the Zn 2p and Ta 4f core level spectra confirmed the presence of Zn²⁺ and Ta⁵⁺ in the ZTC sample. In addition, the infrared spectra identified hydrogen-related defects (HRDs), while the O 1s spectra indicated the existence of oxygen vacancies (VO). Electrochemical tests revealed improvement in the electron conductivity and charge separation of the obtained materials. To follow, the photocatalytic performance assessment was conducted by varying the C/Zn²⁺ ratios (5, 10, and 15 mol%) in ZTC samples, the initial RhB concentration (7, 15, and 30 ppm), and the pH of the RhB solution (3.0–10.0). The photodegradation on ZTC samples showed the most effectiveness for a 7 ppm RhB solution with a C/Zn²⁺ ratio of 10 mol% in the slightly alkaline medium (pH 9.0). Additionally, ZTC also exhibited commendable durability after being reused several times. The nature of RhB photodegradation was proposed and discussed via a mechanism at the end of this work.

In this correspondence, we establish mean convergence theorems for the maximum of normed double sums of Banach space valued random elements. Most of the results pertain to random elements which are M-dependent. We expand and improve a number of particular cases in the literature on mean convergence of random elements in Banach spaces. One of the main contributions of the paper is to simplify and improve a recent result of Li, Presnell, and Rosalsky [Journal of Mathematical Inequalities, 16, 117–126 (2022)]. A new maximal inequality for double sums of M-dependent random elements is proved which may be of independent interest. The sharpness of the results is illustrated by four examples.