Pedagogical Challenges in Online Teaching: A Qualitative Study on Vietnamese University Teachers of Social Sciences

In recent years, online teaching has gained significant traction in higher education institutions across the globe, primarily due to the widespread impact of the Covid-19 pandemic. Before the pandemic, online teaching was mainly associated with distance learning which aims to provide further education for in-service learners. In this context, our study aims to explore the pedagogical obstacles encountered by Vietnamese university teachers when implementing online teaching in social sciences. Employing qualitative research methods, such as snowball sampling and semi-structured in-depth interviews, the researchers gathered data from 23 university teachers specializing in social sciences across 12 public and private universities in Ho Chi Minh City, Vietnam. The findings of this investigation shed light on various pedagogical barriers that impede the teaching process, encompassing aspects such as lesson plan preparation, lecture delivery (limited interactions, teaching methods and activities, students’ distraction and passive participation, managing virtual classrooms), student assessment, and overall teaching ineffectiveness. This study contributes to the existing literature on contextualized online instructions in higher education, specifically focusing on the social sciences domain. Furthermore, the discussion delves into the critical points, providing a comprehensive understanding of the challenges faced by educators in the online teaching landscape

Antimicrobial and antioxidant activity of bacterial endophytes isolated from leaves of the mangrove plant Rhizophora stylosa

Mangroves are the most productive ecosystems and contain highly diverse plants and microbial communities. Mangrove endophytes are proved to be a rich source of bioactive secondary metabolites. The biological molecules produced by endophytes play an important role in protection of mangrove plants against herbivores, insects as well as pathogens. The present study aimed to isolate the endophytic bacteria from the mangrove plant Rhizophora stylosa and screen antimicrobial and antioxidant activity of ethyl acetate extracts from the isolated endophytic bacteria. A total of 64 endophytic bacterial strains from R. stylosa leaves were isolated, of which ethyl acetate extracts of 14 isolated endophytic strains showed antimicrobial activity against at least one of reference microorganisms Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 25923, Bacillus subtilis ATCC 27212, Staphylococcus aureus ATCC 12222 and Candida albicans ATCC 7754 with MIC values from 32 to 512 µg/ml. Among them, four strains showed activity against one reference microorganism, five strains showed activity against two reference microorganisms, four strains showed activity against three reference microorganisms, and one strain showed activity against four reference microorganisms. Additionally, the ethyl acetate extracts of 12 isolated endophytic bacteria showed ATBS and DPPH radical scavenging activity with scavenging values from 36.27 ± 2.6% to 71.46 ± 6.6% and from 26.22 ± 3.3% to 57.38 ± 5.8%, respectively. The identification of the five most active endophytic bacteria by 16S rRNA sequences revealed that the endophytes belonged to four genera, including Bacillus, Streptomyces, Pseudovibrio and Pseudomonas. The obtained results suggest that the endophytic bacteria from mangrove plants are a promising reservoir of antimicrobial and antioxidant agents.      

Investigation of the potential of Brevibacillus spp. for the biosynthesis of nonribosomally produced bioactive compounds by combination of genome mining with MALDI-TOF mass spectrometry

The biosynthetic potential of 11 Brevibacillus spp. strains was investigated by combination of genome mining with mass spectrometric analysis using MALDI-TOF mass spectrometry. These endophytic, plant associated Brevibacillus strains were isolated from crop plants, such as coffee and black pepper, in Vietnam. Draft genomes of these strains were available. They were classified (a) by comparison with type strains and a collection of genome-sequenced Brevibacillus spp. deposited in the NCBI data base as well as (b) by construction of a phylogenetic tree from the core sequences of publicly available genomes of Brevibacillus strains. They were identified as Brevibacillus brevis (1 strain); parabrevis (2 strains); porteri (3 strains); and 5 novel Brevibacillus genomospecies. Our work was specifically focused on the detection and characterization of nonribosomal peptides produced by these strains. Structural characterization of these compounds was performed by LIFT-MALDI-TOF/TOF mass spectrometric sequence analysis. The highlights of our work were the demonstration of the tyrocidines, a well-known family of cyclodecapeptides of great structural variability, as the main products of all investigated strains and the identification of a novel class of pentapeptides produced by B. brevis; B. schisleri; and B. porteri which we designate as brevipentins. Our biosynthetic studies demonstrate that knowledge of their biosynthetic capacity can efficiently assist classification of Brevibacillus species.Peer Reviewe

Arsenic removal from groundwater by a combination of chlorination and consecutive sand filtration

Joint Research on Environmental Science and Technology for the Eart

PRE-ENGINEERED (PACKAGE/AND OR ON-SITE) WASTEWATER TREATMENT PLANTS

Joint Research on Environmental Science and Technology for the Eart

ĐẶC ĐIỂM KHÁNG KHÁNG SINH CỦA VI KHUẨN STREPTOCOCCUS SUIS PHÂN LẬP TỪ LỢN BẢN ĐỊA NUÔI TRÊN ĐỊA BÀN HUYỆN A LƯỚI, TỈNH THỪA THIÊN HUẾ

Streptococcus suis (S. suis) is a Gram-positive bacterium, a common cause of disease in pigs, and is a zoonotic pathogen. The objective of this study was to determine the infection rate, and antimicrobial resistance characteristics of S. suis isolated from local pigs in A Luoi district, Thua Thien Hue province. S. suis was isolated using on blood agar, and identified by PCR method; the antimicrobial resistance was assessed by disk diffusion method and the antimicrobial resistance genes were detected by PCR. The results showed that 33,33% of the samples were positive for S. suis. Most of S. suis isolates were susceptible to neomycin, gentamicin, and erythromycin; but resistant to penicillin, amoxicillin, ampicillin, and tetracycline. The results also showed that, amoxicillin and tetracycline resistance were significantly positively correlated with penicillin resistance; enrofloxacin and gentamicin were significantly negatively correlated with penicillin and ampicillin. A high percentage of S. suis isolates carried gyrA and parC genes (75.61%), Sul1 (70.73%), and ermB (29.27%). There was 92.68% of S. suis isolates showed multidrug resistance and 82.93% of the isolates carried multiple antimicrobial resistance genes.Streptococcus suis (S. suis) là vi khuẩn Gram dương gây bệnh ở lợn và có thể lây sang người. Mục tiêu của nghiên cứu là xác định tỷ lệ nhiễm, đặc điểm kháng kháng sinh của S. suis phân lập được từ lợn bản địa ở A Lưới, Thừa Thiên Huế. S. suis được phân lập trên môi trường thạch máu, định danh bằng phương pháp PCR; kháng kháng sinh được đánh giá bằng phương pháp khuếch tán trên thạch và gene kháng kháng sinh được phát hiện bằng phương pháp PCR. Kết quả cho thấy, có 41/123 (33,33%) con bị nhiễm S. suis. Tỷ lệ cao chủng S. suis nhạy cảm với streptomycin, neomycin, gentamicin và erythromycin; nhưng cũng có tỷ lệ cao đã kháng lại penicillin, amoxicillin, ampicillin và tetracycline. Mối tương quan chặt chẽ giữa tính kháng với amoxicillin và penicillin; tetracycline và penicillin; giữa tính nhạy cảm với enrofloxacin và tính kháng lại penicillin; giữa tính nhạy cảm với gentamicin và tính kháng với ampicillin của các chủng S. suis đã được phát hiện. Tỷ lệ cao các chủng S. suis mang gene gyrA và parC (75,61%), Sul1 (70,73%), và ermB (29,27%). Có 92,68% số chủng S. suis kháng lại nhiều loại kháng sinh và 82,93% chủng mang nhiều gene kháng kháng sinh

20-Hydroxyecdysone from Dacrycarpus imbricatus bark inhibits the proliferation of acute myeloid leukemia cells

Abstract Objective To investigate the anti-proliferative effects of 20-hydroxyecdysone isolated from the bark of Dacrycarpus imbricatus (Blume) de Laub. Methods Column chromatography was used for isolation of compounds from plant material. The structure of the isolated compound was identified by mass spectrometry and nuclear magnetic resonance techniques, including HSQC, HMBC, NOE-difference experiments. The isolated compound was tested for its anti-proliferative activity in acute myeloid leukemia (AML) and OCI-AML cells. Results Compound 1 was isolated from the ethyl acetate fraction of Dacrycarpus imbricatus barks by column chromatography. Its chemical structure was identified as 20-hydroxyecdysone (20HE), a cholestane-type ecdysteroid, by a combination of mass spectrometry and nuclear magnetic resonance spectrometric analyses. Our goal was to test the anti-proliferative activity of 20HE using the OCI-AML cell line. 20HE significantly decreased OCI cell number at a concentration of 1 mg/mL, whereas lower concentrations were ineffective. Moreover, this decrease was due to partial blockage of the G 1 /S phase of the cell cycle, with a reduction of cells in the G 2 M phase, not due to increased apoptosis. Conclusions This indicates that 20HE significantly decreases the number of cells in the G 1 /S phase of the cell cycle in human AML cells. This is the first time that the anti-proliferative activity of 20HE against a human tumor cell line has been reported

Characterization of arsenic-resistant endophytic Priestia megaterium R2.5.2 isolated from ferns in an arsenic-contaminated multi-metal mine in Vietnam

Bioremediation is a biological process to remove or neutralize environmental pollutants. This study was carried out to investing at the efficacy of arsenic resistant endophytic bacteria isolated from Pteris vittata, Pityrogramma calomelanos, Blenchum orientale, and Nephrolepis exaltata, which grow in a highly arsenic (As) contamination mining site in Vietnam. Their segmented roots, stems, and leaves were homogenized separately and inoculated on LB agar plates containing 5mM As(III) and As(V). A total of 31 arsenic resistant endophytic strains were selected, in which strain R2.5.2 isolated from the root of P. calomelanos had the highest arsenic resistant capability. Strain R2.5.2 tolerated up to 320 mM and 160 mM of arsenate and arsenite, respectively. The strain developed well on a media of 0.1 5% NaCl, at 20-40ºC and pH 5 9, and actively utilized most of the sugar sources. It had a high IAA biosynthesis capacity with an average concentration of 19.14 mg/L, tolerated to 0.5-16 mM concentration of Ag+, Hg2+, Co2+, Ni2+, Cu2+, Cr4+, and reduced As(V). Based on 16s rDNA, R2.5.2 was identified as Priestia megaterium. The ars C gene coding for arsenate reductase catalyzing reduction of As(V) was successfully amplified in P. megaterium R2.5.2.  The selected strain may have potential use for bioremediation practice

Two plant-associated Bacillus velezensis strains selected after genome analysis, metabolite profiling, and with proved biocontrol potential, were enhancing harvest yield of coffee and black pepper in large field trials

Elimination of chemically synthesized pesticides, such as fungicides and nematicides, in agricultural products is a key to successful practice of the Vietnamese agriculture. We describe here the route for developing successful biostimulants based on members of the Bacillus subtilis species complex. A number of endospore-forming Gram-positive bacterial strains with antagonistic action against plant pathogens were isolated from Vietnamese crop plants. Based on their draft genome sequence, thirty of them were assigned to the Bacillus subtilis species complex. Most of them were assigned to the species Bacillus velezensis. Whole genome sequencing of strains BT2.4 and BP1.2A corroborated their close relatedness to B. velezensis FZB42, the model strain for Gram-positive plant growth-promoting bacteria. Genome mining revealed that at least 15 natural product biosynthesis gene clusters (BGCs) are well conserved in all B. velezensis strains. In total, 36 different BGCs were identified in the genomes of the strains representing B. velezensis, B. subtilis, Bacillus tequilensis, and Bacillus. altitudinis. In vitro and in vivo assays demonstrated the potential of the B. velezensis strains to enhance plant growth and to suppress phytopathogenic fungi and nematodes. Due to their promising potential to stimulate plant growth and to support plant health, the B. velezensis strains TL7 and S1 were selected as starting material for the development of novel biostimulants, and biocontrol agents efficient in protecting the important Vietnamese crop plants black pepper and coffee against phytopathogens. The results of the large-scale field trials performed in the Central Highlands in Vietnam corroborated that TL7 and S1 are efficient in stimulating plant growth and protecting plant health in large-scale applications. It was shown that treatment with both bioformulations resulted in prevention of the pathogenic pressure exerted by nematodes, fungi, and oomycetes, and increased harvest yield in coffee, and pepper.Peer Reviewe

Evaluation of Luminex xTAG Gastrointestinal Pathogen Panel Assay for Detection of Multiple Diarrheal Pathogens in Fecal Samples in Vietnam.

Diarrheal disease is a complex syndrome that remains a leading cause of global childhood morbidity and mortality. The diagnosis of enteric pathogens in a timely and precise manner is important for making treatment decisions and informing public health policy, but accurate diagnosis is a major challenge in industrializing countries. Multiplex molecular diagnostic techniques may represent a significant improvement over classical approaches. We evaluated the Luminex xTAG gastrointestinal pathogen panel (GPP) assay for the detection of common enteric bacterial and viral pathogens in Vietnam. Microbiological culture and real-time PCR were used as gold standards. The tests were performed on 479 stool samples collected from people admitted to the hospital for diarrheal disease throughout Vietnam. Sensitivity and specificity were calculated for the xTAG GPP for the seven principal diarrheal etiologies. The sensitivity and specificity for the xTAG GPP were >88% for Shigellaspp.,Campylobacterspp., rotavirus, norovirus genotype 1/2 (GI/GII), and adenovirus compared to those of microbiological culture and/or real-time PCR. However, the specificity was low (∼60%) for Salmonella species. Additionally, a number of important pathogens that are not identified in routine hospital procedures in this setting, such as Cryptosporidiumspp. and Clostridium difficile, were detected with the GPP. The use of the Luminex xTAG GPP for the detection of enteric pathogens in settings, like Vietnam, would dramatically improve the diagnostic accuracy and capacity of hospital laboratories, allowing for timely and appropriate therapy decisions and a wider understanding of the epidemiology of pathogens associated with severe diarrheal disease in low-resource settings