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Dichloro-Diphenyl-Trichloroethane (DDTs) are potent organic toxins widely used in agriculture and malaria prevention. The extensive use of DDTs has raised concerns about their adverse impacts. This study aimed to evaluate the toxicity of DDTs on Pacific oyster (Crassostrea gigas) larvae and embryos in the lower Sai Gon-Dong Nai River. We exposed oyster larvae and embryos to sediment samples containing DDT concentrations of 0.01, 0.05, 0.1, 0.5, and 1 mg·k·g-1, as well as artificial seawater samples with DDT levels of 0, 0.1, 1, 10, and 100 µg·L-1. The analysis results revealed a significant adverse impact of DDTs on the survival ratio of larvae and the cell division of embryos in both water and sediment samples compared to control samples. The Effective Concentrations in embryo cell division capacity (EC50) after 2 and 24 h of exposure were 66.88 and 4.62 µg·L-1 in artificial seawater and 1.1 and 0.3 mg·kg-1 in sediment, respectively. Lethal Concentrations (LC50) were 4.62 µg·L-1 and 0.3 mg·kg-1, respectively. Transmission Electron Microscopy (TEM) and Scanning Electron Microscope (SEM) images further confirmed the significant morphological disruptions caused by DDTs after 24 h of exposure. These findings indicate that DDT toxicity poses a threat to oyster farming in coastal areas, where chronic pesticide exposure is likely. [ABSTRACT FROM AUTHOR]

The logistics industry has been as a significant contributor to carbon emissions. Within Vietnam's logistics sector, there is a notable contrast in terms of the quantity of foreign and Vietnamese companies and their respective market shares. This article used a structured survey and descriptive analysis to investigate the low-carbon-emission measures employed by domestic and foreign-invested logistics service providers (LSPs), comparing the results of these two groups, and in-depth interviews were applied for further discussion. The relevant literature was reviewed and expert insights were used to develop a comprehensive questionnaire, resulting in 166 completed responses, of which 159 were suitable for data analysis. The findings reveal variations in the degree to which low-carbon practices are adopted by foreign and domestic firms. In addition to changes in transport modes and the use of energy-saving lighting, the adoption levels of other low-carbon practices show that foreign LSPs exhibit higher engagement compared to their domestic counterparts. This can be attributed to their extensive global operations, greater access to capital resources, and a greater awareness of the importance of green initiatives in developed countries. In conclusion, this study conducts a comparative analysis between foreign-invested and domestic firms, which has not been previously investigated. [ABSTRACT FROM AUTHOR]

Respiratory syncytial virus (RSV) is one of the most interesting respiratory viruses in the world. This virus causes symptoms of illnesses like influenza and imposes a heavy burden on medical services and the economy. However, studies on RSV in Vietnam are limited, while most of the RSV research has primarily been done before 2015. We collected the clinical respiratory samples from severe acute respiratory infection (SARI) patients to screen for RSV by real-time RT-PCR and study their molecular characteristics. RSV-positive specimens with Ct value < 25 collected between 2017−2018 in north Vietnam were inoculated on the Hep2 cell line. The results showed that 25 (22.32%) RSV virus strains were harvested from the inoculation procedure with 18 RSV A and 7 RSV B. The whole genomes of four representative strains were sequenced with the Illumina iSeq 100. Phylogenetic trees analysis of each subtype were classified as two RSV A and two RSV B sequences as genotype ON1 lineage 1.2 and genotype BA9 respectively. These genotypes were identified as typical Vietnamese strains from 2009−2012. Nevertheless, the RSV strains before 2015 and those in this study had significant differences in the G gene, with 34–35 amino acids in RSV A and 4 amino acids in RSV B. Moreover, the first whole genome of Vietnamese RSV since 2016 may give more understanding of the molecular characteristics of RSVs in Vietnam. [ABSTRACT FROM AUTHOR]

Centrifugal force is what causes the vehicle to roll over. This force is generated when the vehicle suddenly changes direction when moving at high speed. The solution of using a stabilizer bar is suggested to minimize this phenomenon. There are currently three types of stabilizer bars in use: mechanical stabilizer bars, hydraulic stabilizer bars, and electronic stabilizer bars. The content of this article is aimed at introducing and reviewing the characteristics of the stabilizer bar. Besides, two oscillation simulation models of vehicles equipped with stabilizer bars are also analysed in this article. Additionally, the characteristics of the control algorithms for the stabilizer bar are clearly analysed. The half-dynamics model is suitable for algorithms that need to use oscillatory state matrices such as SMC, LQR, and LQG. The spatial dynamics model is suitable for some algorithms such as PID, fuzzy, and neural. The roll angle of the vehicle has been significantly improved when the stabilizer bar is fitted. In general, the stability and safety of the vehicle can be guaranteed if the vehicle uses a stabilizer bar. [ABSTRACT FROM AUTHOR]

Functionally graded materials (FGMs) are increasingly used in sandwich construction to improve mechanical performance of structures. The effective material properties used in modelling FGM structures, however, are dependent on a chosen homogenization scheme. For the first time, the influence of different homogenization schemes on large deflections of dual-phase FGM sandwich beams is studied in this paper by using a nonlinear finite element procedure. The material properties of the sandwich beams are considered to vary in the thickness direction by a power function. Four homogenization schemes, namely the schemes due to Voigt, Mori–Tanaka, Hashin–Shtrikman and Tamura–Tomota–Ozawa, are employed to estimate the effective elastic moduli of the beams. Based on the total Lagrange formulation, a first-order shear deformable nonlinear beam element is formulated and employed in the study. Newton–Raphson iterative method is used in combination with the arc-length technique to obtain the large deflection curves and stress distribution of the beams. Numerical results reveal that the material distribution indicated by the material grading index and the homogenization scheme have play an important role on the behaviour of the beams, and the influence of the material grading index on the large deflection response is dependent on the homogenization scheme. Among the four homogenization schemes studied, it is shown that the large deflection response obtained by the Voigt model is more conservative than that using the other schemes. [ABSTRACT FROM AUTHOR]

The phenomenon of vehicle rollover usually occurs when the driver suddenly steers at high speed. The centrifugal force will appear and cause the vehicle's body to tilt. To overcome this situation, the solution of using the stabilizer bar is proposed. The passive stabilizer bar has a simple structure, low cost, and long service life. As a result, it is now a standard on most vehicles. This paper has established a dynamic model to describe a vehicle's oscillation. As a result of the study, the maximum roll angle of the vehicle was reduced from 9.0° to 8.2° when the stabilizer bar was used. Besides, the minimum value of the vertical force at the wheel reached 485(N) and 1162(N), respectively, corresponding to the two survey cases. The movement trajectory of the vehicle when using the stabilizer bar does not have a big difference compared to the case when the vehicle does not use the stabilizer bar. So, the vehicle's stability and safety can be effectively improved. This is the basis for further developing complex stable bar patterns in the future. [ABSTRACT FROM AUTHOR]

Vietnam is one the most vulnerable region to climate change and extreme climatic events, such as flash floods and droughts. This present research aims to explore the farm households' beliefs, risk perception, adaptive attitude and climate change adaptation measures that they currently utilize in their farms to cope with climatic risks. Further, this study analyzed effect of climate change belief, awareness and adaptive attitudes on farmers' adaptive behavior. By using structured questionnaire, the data from 816 respondents were collected from seven provinces of Vietnam. We used ordinary least squares regression and logistic regression approach to analyze farmers' belief, perception of climatic change, and risk attitude towards climatic hazards. Results revealed that farmers in the study area are using the most common climatic risk management strategies including applying new technologies, adjustment of the seasonal calendar, and diversification. Findings further revealed that that farm households were mostly concerned about the risk in soil erosion and washout, followed by the stress of prolonging dry season and droughts. The study participants also reported a decrease in precipitation and increase in temperature and frequency and incidence of other extreme climatic events. A positive significant relationship was found between farm management practices and ecological communities. Risk perceptions and attitude toward climate change are essential factors among farm households of northern mountains of Vietnam. Thus, the climate strain linked with the institutional stress and socio-economic has serious insinuations for farm households' livelihood bases, a universal climate change adaptation scheme is required to endure farmers' livelihood. [ABSTRACT FROM AUTHOR]

This paper presents the study of integrating the remote sensing technology with in-situ ground observation for assessing the status of water quality in Ca Mau city through the Vietnam Water Quality Index (VN-WQI). The Sentinel-2 image and in-situ surface water samples were collected on 20 February 2020 for this study. The sample results were then specified by samples’ coordination. Besides, Sentinel-2 imaging was processed by radiometric and atmospheric correction, geometric registration, and extracted pixel spectral values from the sample locations. The multiple linear regressions of seven water quality parameters including BOD5, COD, NH4, PO4, TSS, pH, Coliform with surface water’s pixel spectral values from the satellite images were calculated and used to simulate water quality parameters on the satellite image. They were integrated into the VN-WQI to estimate, classify, and evaluate the general surface water quality of the Ca Mau city. The results show that there is a regressive correlation between measured data and image spectral values, and the simulation also well fits with the data with an acceptable error. The surface water quality of Ca Mau city is heavily polluted with almost all water quality parameters recognized at B1 to above B2 level according to the QCVN08-MT:2015/BTNMT. In terms of VN-WQI, the results also illustrate the low quality of surface water and heavy pollution only used for water transportation, not for domestic use. This approach can be a powerful method in spatially monitoring water quality and supporting environment management. [ABSTRACT FROM AUTHOR]

This study was conducted from May to November 2017 to evaluate the accumulation of organochlorine pesticide chemicals (OCPs) in fish, Bostrychus sinensis, growing at the Soai Rap estuary, Ho Chi Minh City, Vietnam. The pesticide chemicals in the tissues of fish and the sediments of the estuary were analyzed using a gas chromatography method and Varian GC-450 (ECD) instrument. The results showed that in all tissue samples of fish, the content of DDTs was the highest (9.524 ng/g), followed by aldrin (1.209 ng/g); HCHs (1.972 ng/g); dieldrin (1.743 ng/g) and endosunfans (1.053 ng/g), and the lowest values were Heptachlor (0.807 ng/g) and Eldrin (0.715 ng/g). The content of OCPs in all sediment samples from the study area was found to be lower than Vietnamese standard 43: 2012 /MONRE and some other standards in the world. The bioaccumulation factor of OCPs in the tissue of fish was very low level (BAF < 100), for DDTs at low levels (100 < BAF < 500). The Biota-Sediment Accumulation Factor (BSAF) of the seven substances in the sediment was Dieldrin > DDTs > Aldrin > HCHs > Endosunfans > Heptachlor > Endrin. [ABSTRACT FROM AUTHOR]