Published: 2022-06-27

Antibacterial resistance of Vibrio parahaemolyticus isolated from shrimp farms located in east coastal region of the Mekong Delta, Vietnam

Thi Hoang Oanh Dang, Truong Quoc Phu, Nguyen Thanh Phuong
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The study was conducted to evaluate the susceptibility of 58 Vibrio parahaemolyticus bacterial isolates to 16 antibiotics. These bacterial isolates were recovered from diseased shrimp which displayed typical pathology of AHPND such as hepatopancreatic atrophy, empty gut, and hepatopancreatic changes including hemocytic infiltration and bacterial infection. Results of antibiotic susceptibility testing by the disk diffusion method showed that single resistance to tested antibiotics was relatively rare. The bacterial strains were resistant to amoxicillin (100%), cephalexin (100%), Sulfadiazine Sodium (94.7%), and Erythromycin (87.7%). Sensitivity of tested strains was recorded with doxycycline (84.2%) and oxytetacylin (49%). The minimum inhibitory concentrations (MICs) were determined for the sensitive isolates using a broth macro dilution method. The majority of tested isolates had an MIC value of 2μg/mL with doxycycline. The current study suggests caution in the use of antibiotics for the prevention and treatment of AHPND in shrimp farming.

Characteristics of lightweight foamed concrete with various contents of polypropylene fiber

Ngo Si Huy, Ho Si Lanh, Trong Phuoc Huynh
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This study investigates the influence of polypropylene (PP) fiber content on the mechanical properties of lightweight foamed concrete (LFC). Four LFC mixtures with a target dry density of 1000 kg/m3 were designed with different PP fiber volumes of 0%, 0.25%, 0.5%, and 0.8%. The fresh unit weight (UW), dry density, compressive and flexural strengths, water absorption, thermal conductivity, ultrasonic pulse velocity (UPV), and scanning electron microscopy (SEM) of the LFC were examined. The results indicate that the fresh UW, dry density, UPV, and thermal conductivity decreased when the PP content varied from 0% to 0.8%. At 28 days, the compressive and flexural strengths of the LFC increased approximately 11.85% and 41.8% when the PP fiber amount varied from 0% to 0.8%, respectively. The result implies that the PP fiber content had a higher influence on the flexural strength content than the compressive strength. Furthermore, the results of SEM could explain well the obtained mechanical properties. The findings of this study indicate that PP fiber could be used up to 0.8% by volume to reduce the self-weight of the LFC and enhance the mechanical strength as well as thermal isolation characteristics of the LFC.

Preparation of Fe3O4/HAp nanoparticles from eggshells with highly adsorption capacity for methylene blue

Huynh Vu Thanh Luong, Ngọc Hân Nguyễn, Gia Hân Khưu, Yến Pha Bùi, Quang Quốc Việt Thiều, Ngo Truong Ngoc Mai, Tran Thi Bich Quyen
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Multifunctional materials have become one of the most interesting research subjects in recent years. Hydroxylapatite (HAp) coating on the surface of iron oxide (Fe3O4) nanoparticles allow to obtain material with adsorbable and magnetic properties. This study aims to salvage recycled eggshell to successfully produce adsorbent nanoparticles and evaluate treatment ability of methylene blue (MB) dyes in water. The magnetic nanomaterial was synthesized by a simple and inexpensive method. The X-ray diffraction technique was employed to characterize the structure of nanoparticles. The as-synthesized nanoparticles were analyzed by Fourier transform infrared spectroscopy technique to determine the presence of functional groups and bonds in the molecule. The surface morphology of as-synthesized Fe3O4/HAp nanoparticles was studied by transmission electron microscopy. The magnetic properties of Fe3O4 nanoparticles and Fe3O4/HAp nanoparticles were evaluated by vibrating sample magnetometer technique. The typical synthesized-HAp were dispersed rod-like particles with about 10 nm in width and 50 nm in length, the other part of final material was dispersed in spherical shape and their magnetism was 16.2 emu.g-1. The adsorption of MB was conducted with 89.6% yield at pH 8.

The influences of oral communication strategies on students’ English speaking proficiency

Nguyen Thi Thanh Ha, Viet Phuong Vu, Do Thi Tieu Yen
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This study aims to examine the spoken communication techniques of non-English major students at University of Economics – Technology for Industries (UNETI) to get a better knowledge of language acquisition techniques, namely oral strategies used in communicative activities. Data were collected through questionnaire adapted from the Oral Communication Strategy Inventory (OCSI) by Nakatani (2005) and analyzed using OCSI. Participants were 50 EFL students from the Faculty of Accounting, UNETI. The results show that students utilized certain communication strategies (CSs) when they encountered oral communication difficulties. It was additionally anticipated that UNETI students would think more deeply about their oral communication abilities. Consequently, teachers will develop more effective methods of teaching them how to communicate successfully with others throughout the process. Moreover, students will acquire additional CSs that they may use more effectively in real-world conversations with native and non-native speakers. Thus, speaking strategy training should not be overlooked throughout students’ learning process.

Disease incidence in shrimp farms located in east coastal region of the Mekong Delta, Vietnam

Thi Hoang Oanh Dang, Truong Quoc Phu, Nguyen Thanh Phuong
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A field study on the water quality parameters and prevalence of diseases was carried out in four locations in the Mekong Delta, Vietnam. A total number of 960 samples (816 with disease signs and 144 without disease sign) of farmed shrimp were collected over 8 sampling months (2 production cycles). Samples were collected every two weeks and when abnormal behavior from cultured shrimp was observed. Five major groups of gross clinical signs were recorded among diseased shrimp samples. Diseases that appeared through the sampling months were: (1) atrophy and pale-colored hepatopancreas (HP) with the empty or little food in the mid gut; (2) empty/little/discontinued food in the midgut and (3) slow growth, HP atrophy and gut with discontinued food. White feces disease was not found in April but appeared for the rest of sampling months with the highest prevalence in July (39,2%) and the lowest prevalence in September (4,9%). White spot disease appeared from October to December (at the end of when the monsoon season and low temperature).

Effects of dietary protein and lipid levels on growth, feed utilization and meat quality of clown knifefish (Chitala chitala)

Thi Thanh Hien Tran, Lam My Lan, Tran Le Cam Tu
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Effects of dietary protein and lipid levels on growth, feed utilization and fillet quality of clown knifefish (Chitala chitala) were implemented to determine the protein and energy requirements of this species at 400 g stage. A 4 x 3 factorial design with four dietary protein levels (25%, 30%, 35% and 40%) and three dietary lipid levels (6, 9, and 12%) corresponded to 3 energies levels 18, 19 and 20 MJ/kg. Clown knifefish (407 ± 5.0 g) was stocked at a density of 10 fish/m2. The experiment was arranged in a completely randomized design  in triplicate tanks for 8 weeks. There was a significant interaction effect (P0.05) by dietary protein and lipid levels and ranged from 93.3 to 100%. The feed efficiency of fish was influenced by dietary protein or lipid content as well as the interaction between these two factors. Protein utilization efficiency increased as protein content increased, and diet contained t 35% protein and 9% lipid,  enhanced chewiness and hardness of fish paste. These results showed that clown knifefish fed 32.8% dietary protein and 19 MJ energy with a P/E ratio of 18.6 had the optimal growth and the best quality of fish meat.

Bioactive compounds and strategy processing for acerola: A review

Quang Binh Hoang, Ngoc Tram Pham, Trung Thien Le, Thi Ngoc Diep Duong
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Various studies have evaluated that acerola fruit is one of the best natural sources of vitamin- C. Besides that, the fruits also contain a high level of phenolic and carotenoids. The result tested in vitro performed that acerola extract can be antioxidative, anti-inflammatory, antihyperglycemic, antitumor antigenotoxic and hepatoprotective activity. The techniques such as pasteurization, fermentation, extraction, drying, encapsulation can diversify acerola products.

The effects of extraction conditions on the yield of crude pectin extract from passion fruit (Passiflora edulis Sims.) and the application of the extract on jam forming ability

Trung Hau Nguyen, Hoai Xuan Nu Tran, Thi Thuy Vu, Thi Thuy Linh Ho, Thi Tuong Van Nguyen
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The peel of purple passion fruit (Passiflora edulis Sims.) can account for up to 60% of the total weight and contains usable organic compounds such as polymeric sugars, including pectin. The influences of ripeness stages and the extraction conditions (solvents, peel to solvent ratio, temperature, time) on the extract of crude pectin yield were investigated. The results indicated that pectin yield was independent of fruit maturation. The extraction efficiency reached its peak when extracted with citric acid and demonstrated optimal pectin production yield with the ratio of 1:5 (w/v) and at 95°C for 80 minutes. The extracted crude pectin was then applied to mango jam production. Jam made from extracted pectin had a good structure, moderate hardness, nice color, and harmonious taste. The ability to form coagulation on mango jam of crude pectin was weaker than commercial pectin. This study found that the topic's practical applicability to the processing of food products was significant.

Docking-Based Virtual Screening for the Discovery of 1,3,4-Oxadiazoles as Aminoacyl-tRNA Synthetase Inhibitors

Bui Thi Buu Hue, Cuong Quoc Nguyen, Quang De Tran
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Aminoacyl-tRNA synthetases (aaRSs) are one of the leading targets for the development of antibiotic agents. In this paper, we reported the discovery of aaRS inhibitors using a structure-based virtual screening method. The interactions of 52 designed structures with the methionyl-tRNA synthetase (MetRS) target were performed by docking the ligands into the active zone of the MetRS using Autodock Vina. The data revealed 14 compounds displaying interactions with key amino acids (Asp287, Tyr250, Val473, Trp474, Phe522, Ile519, Ala477, Leu478, and His523) at the binding pocket of the enzyme, indicating their potential as MetRS inhibitors. These results could be served as the references for further synthetic work and bioassays experiments for discovering MetRS inhibitors and other pharmaceutical agents that may assist in the generation of new antibiotics.

Synthesis of silver nanoparticles using extract of Citrus maxima peel

Nguyen Dien Trung; Nguyen Phuong Tung Le; Thi Hong Nguyen
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In this work, silver nanoparticles (AgNPs) were synthesized by the extract of Citrus maxima (C. maxima) peel with the presence of pectin as a principal reductant and stabilizer. Parameters such as concentration of C. maxima powder, extraction temperature, and extraction time for AgNPs synthesis have been studied. The synthesized AgNPs were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and transmission electron microscopy instrument (TEM). The synthesized AgNPs were quasi-spheres with an average particle size of 17 nm and high purity of silver phases. In addition, synthesized AgNPs exhibited good antibacterial activity against Gram-positive bacteria: Salmonella enterica (S. enterica) and Pseudomonas aeruginosa (P. aeruginosa) while no activity inhibited against Gram-negative bacteria: Staphylococcus aureus (S. aureus) and Lactobacillus fermentum (L. fermentum).

Quinazolinone based hydroxamates as anti-inflammatory agents

Bui Thi Buu Hue, Vinh Quang Hong, Cuong Quoc Nguyen, Quang De Tran
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Five thioether-linked hydroxamate/quinazolinone hybrid structures were synthesized and tested for their anti-inflammatory activities. The obtained results indicated that compounds 7a-c and 7e showed the inhibition on LPS-stimulated NO production with the IC50 values ranging from 58.03 to 66.19 mM. Molecular docking results showed that all synthesized compounds displayed affinity towards the 5-LOX, MK2, P2Y12, 15-PGDH, and DNA polymerase receptors based on the observed low binding energies and interactions with the key amino acids in the binding sites of the enzymes. Noticeably, compound 7e exhibited as a potential compound targeting six receptors including 5-LOX, MK2, mPGES-1, P2Y12, 15-PGDH, and DNA polymerase receptors.