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  • Author: Thi Chinh Nguyen x
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Abstract

Introduction

African swine fever (ASF) was officially reported in Vietnam in February 2019 and spread across the whole country, affecting all 63 provinces and cities.

Material and Methods

In this study, ASF virus (ASFV) VN/Pig/HaNam/2019 (VN/Pig/HN/19) strain was isolated in primary porcine alveolar macrophage (PAM) cells from a sample originating from an outbreak farm in Vietnam’s Red River Delta region. The isolate was characterised using the haemadsorption (HAD) test, real-time PCR, and sequencing. The activity of antimicrobial feed products was evaluated via a contaminated ASFV feed assay.

Results

Phylogenetic analysis of the viral p72 and EP402R genes placed VN/Pig/HN/19 in genotype II and serogroup 8 and related it closely to Eastern European and Chinese strains. Infectious titres of the virus propagated in primary PAMs were 106 HAD50/ml. Our study reports the activity against ASFV VN/Pig/HN/19 strain of antimicrobial Sal CURB RM E Liquid, F2 Dry and K2 Liquid. Our feed assay findings suggest that the antimicrobial RM E Liquid has a strong effect against ASFV replication. These results suggest that among the Sal CURB products, the antimicrobial RM E Liquid may have the most potential as a mitigant feed additive for ASFV infection. Therefore, further studies on the use of antimicrobial Sal CURB RM E Liquid in vivo are required.

Conclusions

Our study demonstrates the threat of ASFV and emphasises the need to control and eradicate it in Vietnam by multiple measures.

Abstract

Silica nanoparticles (SNPs) were modified by different amounts of 3-aminopropyltriethoxysilane (APTES). Nanocomposites based on ethylene vinyl acetate copolymer (EVA) and modified SNP (m-SNP) were prepared by the melt mixing method. They were characterized by Haake torque measurement, differential scanning calorimetry (DSC), horizontal burning test, scanning electron microscopy. Accelerated weather testing of the nanocomposites was performed according to ASTM D4329 (cycle A) for 168 h. The Haake torque indicates that the relative melt viscosity of EVA/m-SNPs is slightly higher than that of EVA/SNP nanocomposites. The DSC and burning test results show that m-SNPs decrease crystallinity degree and flammability of EVA. After accelerated weather testing, the relative amount of C=O groups in EVA/m-SNP nanocomposites is lower than that in EVA/SNP nanocomposites. Micro crack of EVA/m-SNP nanocomposite is smaller than that of EVA/SNP nanocomposite. In our study, the EVA/m-SNP nanocomposites with good tensile properties, flame and weather resistance can be used as sustainable materials in some technique fields.

Abstract

Poly(lactic acid)/chitosan (PLA/CS) green nanoparticles containing hydroquinine (Hq) were prepared by emulsion method. The content of Hq was 10–50 wt% compared with the weight total of PLA and CS. The characteristics of these nanoparticles were analyzed by Fourier transform infrared (FTIR), differential scanning calorimetry, field emission scanning electron microscopy (FESEM), and particle size analysis. The wavenumbers of C=O, C=N, OH, and CH3 groups in FTIR spectra of the PLA/CS/Hq (PCHq) nanoparticles shifted in comparision with neat PLA, CS, and Hq that proved the interaction between these components. The FESEM images and particle size analysis results showed that the basic particle size of PCHq nanoparticles ranged between 100 and 200 nm. The Hq released from PLA/CS nanoparticles in pH 2 and pH 7.4 solutions was determined by ultraviolet-visible method. The obtained results indicated that the linear regression coefficient of calibration equation of Hq in the above solutions approximates 1. The Hq release from the PCHq nanoparticles includes fast release for the eight first testing hours, and then, controlled slow release. The Hq released process was obeyed according to the Korsmeyer-Peppas kinetic model.

Abstract

Green nanocomposites based on poly(lactic acid), chitosan, and polyethylene glycol (PLA/CS/PEG) were prepared by the solution method. The content of PEG was 2–10 wt.% compared with the weight of PLA. The characterization and morphology of the nanocomposites before and after hydrolysis in acid solution were determined by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry and scanning electron microscopy (SEM). The hydrolysis of PLA/CS/PEG nanocomposites in acid solution for different times was also investigated. The shift of C=O, CH3 groups in FTIR spectra of PLA/CS/PEG nanocomposites before and after hydrolysis was clearly observed. The SEM images of the nanocomposites indicate that PEG plays a role in improving the interaction between PLA and CS, resulting in limiting the permeability of acid solution into the structure of the nanocomposites in the presence of PEG. The obtained results after 28 days of testing in the acid solution show that the PLA/CS/PEG8 nanocomposite (containing 8 wt.% of PEG) had the lowest weight loss with the highest regression coefficient (R2=0.9614).

Abstract

According to traditional rough set theory approach, attribute reduction methods are performed on the decision tables with the discretized value domain, which are decision tables obtained by discretized data methods. In recent years, researches have proposed methods based on fuzzy rough set approach to solve the problem of attribute reduction in decision tables with numerical value domain. In this paper, we proposeafuzzy distance between two partitions and an attribute reduction method in numerical decision tables based on proposed fuzzy distance. Experiments on data sets show that the classification accuracy of proposed method is more efficient than the ones based fuzzy entropy.