Quy trình gia công và phân tích hóa thạch Tảo vôi, áp dụng cho các trầm tích ven biển tỉnh Sóc Trăng

Calcareous nannofossils are very small microfossils composed of calcium carbonate. They are very good biostratigraphic markers within marine sediments by covering the Jurassic to present. The standard preparation of a sample for nannofossil analysis requires the collection of the largest quantity and the best fossils. Sample preparation accords to the following steps: i. Pounding sample; ii. Eliminating organic matter; iii. Washing sample; iv. Filter sample through the sieve; v. Eliminating clay; vi. Drying sample in an incubator; vii. Packing sample. Sample analysis accords to the following steps: i. Preparation of smear - slide; ii. Observation of morphology; iii. Determination; iv. Taking photo; v. Evaluating overall preservation and abundance of fossils; vi. Making analysis result sheet. This process is applied to study calcareous nannofossils within marine sediments in Soc Trang province. It makes much clear to understand middle Pleistocene-early Holocene ecosystem of calcareous nannofossil. In conclusion, this assemblage belongs to NN21 zone by the present of Emiliania huxleyi and Gephyrocapsa oceanica.Hóa thạch Tảo vôi có kích thước rất nhỏ, thành phần chính là canxi carbonat. Chúng là hóa thạch định tầng rất tốt cho các trầm tích biển có tuổi từ Jura đến nay. Để nghiên cứu hóa thạch Tảo vôi, cần tiến hành gia công và phân tích mẫu theo đúng quy trình để thu được lượng hóa thạch nhiều nhất và bảo tồn tốt nhất. Quy trình gia công gồm các bước sau: i. giã mẫu; ii. tẩy keo hữu cơ; iii. rửa mẫu; iv. lọc mẫu; v. tẩy sét; vi. sấy mẫu; vii. đóng gói. Quy trình phân tích tiến hành theo những bước sau: i. chuẩn bị tiêu bản; ii. nghiên cứu đặc điểm hình thái của hóa thạch; iii. xác định hóa thạch; iv. chụp ảnh hóa thạch; v. đánh giá mức độ bảo tồn và phong phú của hóa thạch; vi. lập phiếu kết quả phân tích. Kết quả áp dụng quy trình cho các trầm tích ven biển tỉnh Sóc Trăng đã góp phần làm sáng tỏ hệ sinh thái Tảo vôi ở khu vực nghiên cứu trong Pleistocen giữa - Holocen sớm. Tập hợp hóa thạch ở khu vực ven biển Sóc Trăng thuộc sinh đới NN21 với bằng chứng là sự xuất hiện của Emiliania huxleyi và Gephyrocapsa oceanica

Synthesis and Optical Characterization of Dye Doped in Ormosil Nanospheres for Bioapplications

Dye-doped ORMOSIL (organically modified silicate) nanoparticles (NPs) have significant advantages over single-dye labeling in signal amplification, photostability and surface modification for various biological applications. The dyes: Rhodamine 6G (R6G) and Rhodamine B (RB) were successfully incorporated into ORMOSIL nanoparticles fabricated by micellar nanochemistry from Trimethoxysilane CH$_3$Si(OCH$_3$)$_3$ precursor. The optical characterization of dye-doped ORMOSIL NPs was studied in comparison with it’s of free dye in solution. The results shown that the photostability of ORMOSIL dye doped nanospheres is much improved in comparison with it’s of dye in solution. Other studies of the photophysical properties such as anisotropy, fluorescence lifetime and energy transfer were also done

Factors Affecting Consumers’ Impulsive Purchasing Behavior in Circle K Convenience Stores in Hanoi, Vietnam

Impulsive purchasing behavior has been observed as one of the important studies conducted by marketers and researchers, as impulse buying has become a prevalent phenomenon in every retail format. The study was conducted to assess factors affecting consumers’ impulsive purchasing behavior in Circle K convenience stores in Hanoi, Vietnam. After reviewing a group of previous studies, the authors indicated 05 factors that affected consumers' impulsive purchasing behavior including impulsiveness, instant gratification, visual appeal, promotions and money availability. The study had selected 05 experts in the field of economics to conduct the expert interview. Moreover, the research team had also handed out the questionnaire and received 310 observations. Specifically, Impulsiveness had the strongest influence on the impulsive purchasing behavior of Circle K’s consumers in Hanoi. Keywords: factors, Impulsive purchasing behavior, Circle K convenience stores DOI: 10.7176/JESD/14-8-03 Publication date: April 30th 2023

The effect of some factors on expression of gene encoding endoglucanase from dna metagenome of Binh Chau hot spring in Escherichia coli

Expression of microbial target genes in Escherichia coli is broadly used due to its advantages namely: well established system, easy to manipulate, a huge biomass, high level productivity, safe and inexpensive to grow. Metagenomic technique has been applying in Vietnam recently for effective mining of uncultured gene resources, especially in endemic mini-ecologies such as hot springs where the cell densities are low. DNA metagenome of Binh Chau hot spring was isolated and sequenced by Illumia HiseqTM. Based on analyses of databases of cellulase-encoded genes, denovogenes 18736 gene sequence for thermal endoglucanase was selected for expression in E. coli. In this paper, some factors for expression of endoglucanase have been investigated. The results show that appropriate gene expression conditions are:  Expression performed in E. coli C43 (DE3) on TB medium at 30oC with 0.25 mM of IPTG as inducer, the culture volume of 20% compared with the bottle volume and the expression time is 42–48 hours. In this condition, the biomass production and soluble enzyme activity can reached up to 5.54–5.58 g /L and  1.92–1.98 U/mL, respectively. Our results show the prospect of exploiting microbial genes without culture

INVESTIGATING THE ANTI-INFLAMMATORY ACTIVITY OF AN ETHANOLIC EXTRACT FROM ARTOCARPUS TONKINENSIS LEAVES USING A COLLAGEN ANTIBODY-INDUCED ARTHRITIC MOUSE MODEL

The obtained results here demonstrate that the 70% ethanolic leaf extract of A. tonkinensis (AT2), traditionally used in Vietnamese folk medicine for treating arthritic symtoms, has beneficial effects on pro-inflammatory cytokine inhibition and in an experimental arthritic mouse model. LPS-stimulated RAW 264.7 macrophages treated with AT2 showed a significant decrease in the production of IL-6 and TNFa at concentrations of 12.5, 25 and 50 µg/mL (P0.05), indicating its potential anti-inflammatory properties. Treatment of CAIA mice with AT2 also led to diminish the incidence of arthritis at doses of 200 and 300 mg/kg body weight

Diterpenoids from Fokienia hodginsii.

In continuous research on the chemical constituents of the twigs and leaves of Fokienia hodginsii (Dunn) A. Henry et Thomas growing in Highland, Lam Dong province 4 diterpenoids, including 3-oxo-totarol (totarolone, 1), 3β-hydroxytotarol (2), 15-nor-labda-8(17),12E-diene-14-carboxaldehyde-19-oic acid (3) and 13-oxo-15,16-dinorlabda-8(17),11E-diene-19-oic acid (4) were isolated. Their structures were elucidated by the spectroscopic methods and comparison with reported data. This is the first report on the isolation of compounds 1, 2 and 3 from this plant. Keywords. Fokienia hodginsii; totarane; nor-labdane diterpenoid

Rifampicin resistant 'Mycobacterium tuberculosis' in Vietnam, 2020–2022

Objective: We conducted a descriptive analysis of multi-drug resistant tuberculosis (MDR-TB) in Vietnam’s two largest cities, Hanoi and Ho Chi Minh city. Methods: All patients with rifampicin resistant tuberculosis were recruited from Hanoi and surrounding provinces between 2020 and 2022. Additional patients were recruited from Ho Chi Minh city over the same time period. Demographic data were recorded from all patients, and samples collected, cultured, whole genome sequenced and analysed for drug resistance mutations. Genomic susceptibility predictions were made on the basis of the World Health Organization’s catalogue of mutations in Mycobacterium tuberculosis associated with drug resistance, version 2. Comparisons were made against phenotypic drug susceptibility test results where these were available. Multivariable logistic regression was used to assess risk factors for previous episodes of tuberculosis. Results: 233/265 sequenced isolates were of sufficient quality for analysis, 146 (63 %) from Ho Chi Minh City and 87 (37 %) from Hanoi. 198 (85 %) were lineage 2, 20 (9 %) were lineage 4, and 15 (6 %) were lineage 1. 17/211 (8 %) for whom HIV status was known were infected, and 109/214 (51 %) patients had had a previous episode of tuberculosis. The main risk factor for a previous episode was HIV infection (odds ratio 5.1 (95 % confidence interval 1.3–20.0); p = 0.021). Sensitivity for predicting first-line drug resistance from whole genome sequencing data was over 90 %, with the exception of pyrazinamide (85 %). For moxifloxacin and amikacin it was 50 % or less. Among rifampicin-resistant isolates, prevalence of resistance to each non-first-line drug was < 20 %. Conclusions: Drug resistance among most MDR-TB strains in Vietnam’s two largest cities is confined largely to first-line drugs. Living with HIV is the main risk factor among patients with MDR-TB for having had a previous episode of tuberculosis

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions