One modification of k-ε turbulent model of two-phase flows

A modification of k-ε turbulent model is described with application to the numerical investigation of two-phase turbulent jets. In difference of existed two-parameter models, new three-parameter modification have been suggested. In this case an additional equation for transportation of turbulent energy of admixture – kP is used together with equations of transportation of carrier-phase turbulent energy – kg and its dissipation - ε. Additional dissipation terms in the above mentioned equations are defined in connection with a new examination of the between-phases interaction forces determining jet flows

Development of a diagnostic scar marker for Vibrio shilonii caused acute hepatopancreatic necrosis disease in whiteleg shrimp

Background: In a previous report, we showed that Vibrio shilonii was found on whiteleg shrimp (Litopenaeus vannamei) with acute hepatopancreatic necrosis disease in Thua Thien Hue province, Vietnam. This study was performed to develop a diagnostic molecular marker generated by random amplified polymorphic DNA (RAPD) for V. shilonii rapid detection.Methods: Pathogen Vibrio spp. were isolated from shrimps and fishes, and were identified by 16S rRNA sequencing. Genetic diversity of Vibrio strains was analysis by RAPD technique. Specific PCR product for V. shilonii was cloned and sequenced. SCAR marker was developed from specific PCR product.Result: Twenty random primers were evaluated for RAPD to identify DNA polymorphisms between Vibrio species. The random primer OPN-06 generated a 468-bp DNA fragment specific for V. shilonii. This was then converted into a sequence-characterized amplified region (SCAR) marker designated N6-441.Conclusion: Specific primers (Vshi-441F/Vshi-441R) amplified a unique DNA fragment in all V. shilonii isolates but not in the other Vibrio spp. This PCR assay showed significantly sensitive to the target DNA and reliably for the amplification the V. shilonii genome.Keywords: AHPND; RAPD; SCAR; Vibrio shilonii; Vietna

Chemical constituents of Chirita drakei Burtt collected in Ha Long bay, Quang Ninh province, Viet Nam. Part 1. Compounds isolated from the n-hexane and ethyl acetate extracts.

Two triterpenes, an anthraquinone, two lignans and a phenolic compound were isolated from the n-hexane and ethyl acetate extracts of the aerial part of Chirita drakei Burtt collected in islands, on mountain slopes of Ha Long bay, Quang Ninh province. Their structures have been elucidated by mass, NMR spectroscopy and comparison with published data. There are no report on the chemical constituents of Chirita drakei before our study. Keywords. Chirita drakei, triterpene, anthraquinone, lignin

Promoting skills-based education in the 21st century: A dataset of Vietnamese secondary students

As the world has become more digitally interconnected than ever before in the 21stcentury, the next generation is required to possess various sets of new skills to succeed in their works and lives. The purpose of the article is to present a dataset of socio-demographic, in-school, out-of-school factors as well as the eight domains of 21st-century skills of Vietnamese secondary school students. A total of 1183 observations from 30 secondary schools in both rural and urban areas of Vietnam are introduced in this dataset. The linear regression analysis was also utilized as an analysis example for this dataset. The insights generated from the dataset are hoped to contribute to skills-based education and policy planning in Vietnam

GENETIC POLYMORPHISM OF 23 Y-CHROMOSOME SHORT TANDEM REPEAT LOCI IN THE KINH POPULATION OF VIETNAM

Y-chromosome microsatellites or short tandem repeats (STRs) have been proved to be ideal markers to delineate the differences between individuals in human population. Nowadays, Y-STR testing using the PowerPlex® Y23 amplification kit is considered as an extremely sensitive analysis method and has the potential to be used to perform forensic caseworks, and to explore the complexity in population substructures. However, little is known about the forensic Y-chromosome databases in the Vietnam population. In this study, 23 Y-STR loci (DYS576, DYS389I, DYS389 II, DYS448, DYS19, DYS391, DYS481, DYS549, DYS533, DYS438, DYS437, DYS570, DYS635, DYS390, DYS439, DYS392, DYS393, DYS458 DYS456, DYS643, YGATAH4, and DYS385a/b) were investigated in 120 non-related males of the Kinh population in Northern Vietnam using PowerPlex® Y23 system kit (Promega). Our results showed that allele frequencies of 23 loci in the sample population, with the calculated average gene diversity (GD) for each locus, ranged from 0.24 (DYS438) to 0.92 (DYS385a/b). In addition, a total of 120 different haplotypes were found, all of them were unique. Therefore, we found that the haplotype diversity was 1 with a discrimination capacity of 100%, which serves as an essential prerequisite for using Y-chromosomal STR with PowerPlex® Y23 System kit in forensic application in Vietnam. We also compared genetic distances between Kinh population and 10 other neighboring populations from Y-chromosome haplotype reference database (YHRD). The Kinh population is significantly different from other populations. In conclusion, it was indicated that the 23 Y-STR loci were highly genetically polymorphic in the Kinh population in Vietnam and might be of great value in forensic application

ẢNH HƯỞNG CỦA DỊCH CHIẾT VI KHUẨN LAM ĐẾN NHÂN GIỐNG IN VITRO CÂY LAN HOÀNG THẢO GIẢ HẠC (Dendrobium anosmum Lindl.)

Protocorms of 4-week-old Dendrobium anosmum Lindl. were used as initial material for in vitro propagation. The stock extract of Arthrospira sp. was prepared by grinding 1 g of fresh biomass in 100 mL of distilled water. The in vitro propagation results show that the cyanobacterial extract has the effect of enhancing shoot multiplication and rooting of Dendrobium anosmum. An MS basal medium supplemented with 6 g·L–1 agar, 30 g·L–1 saccharose, and 1.5 mg·L–1 BAP in combination with 20 mL·L–1 cyanobacteria extract was suitable for protocorm multiplication with a protocorm cluster diameters of 2.43 cm. An MS medium supplemented with 6 g·L–1 agar, 30 g·L–1 sucrose, and 1.0 mg·L–1 BAP combined with 20 mL·L–1 cyanobacterial extract was optimal for shoot multiplication. The number of shoots/explant reached 4.7 and a shoot height of 1.37 cm. An MS medium supplemented with 6 g·L–1 agar, 30 g·L–1 sucrose, and 1.5 mg·L–1 NAA in combination with 30 mL·L–1 cyanobacteria extract was the most suitable for rooting with 4.87 roots/bud; the root length was 0.74 cm, and the shoot height was 2.76 cm. These results would open up the application of cyanobacterial extract to reduce costs in plant tissue culture technology.Protocorm của cây lan Hoàng thảo Giả hạc (Dendrobium anosmum Lindl.) bốn tuần tuổi được sử dụng để làm vật liệu khởi đầu cho nhân giống in vitro. Dịch chiết gốc vi khuẩn lam Arthrospira sp. được tạo thành bằng cách nghiền 1 g sinh khối tươi trong 100 mL nước cất. Kết quả cho thấy dịch chiết vi khuẩn lam có tác dụng tăng cường sự nhân chồi và ra rễ của cây lan Hoàng thảo Giả hạc nuôi cấy in vitro. Môi trường MS cơ bản bổ sung 6 g·L–1 agar, 30 g·L–1 saccharose và 1,5 mg·L–1 BAP kết hợp với 20 mL·L–1 dịch chiết vi khuẩn lam thích hợp cho sự nhân protocorm và môi trường tối ưu cho nhân chồi. Đường kính cụm protocorm thu được là 2,43 cm. Môi trường MS cơ bản bổ sung 6 g·L–1 agar, 30 g·L–1 saccharose và 1,0 mg·L–1 BAP kết hợp với 20 mL·L–1 dịch chiết vi khuẩn lam là môi trường tối ưu cho nhân chồi, số chồi/mẫu đạt 4,7; chồi cao 1,37 cm. Môi trường MS cơ bản bổ sung 6 g·L–1 agar, 30 g·L–1 saccharose và 1,5 mg·L–1 NAA kết hợp với 30 mL·L–1 dịch chiết vi khuẩn lam thích hợp nhất cho tạo rễ từ chồi in vitro với 4,87 rễ/chồi; chiều dài rễ là 0,74 cm và chiều cao chồi là 2,76 cm. Kết quả này sẽ mở ra triển vọng ứng dụng dịch chiết vi khuẩn lam giúp giảm chi phí trong công nghệ nuôi cấy mô tế bào thực vật

TAX COMPLIANCE OF SMALL AND MEDIUM ENTERPRISES: A CASE STUDY IN THUA THIEN HUE

Tax compliance is the concern of many researchers and tax managers. Based on secondary data from tax authorities and primary data collected from 362 small and medium enterprises (SMEs), we assess the tax compliance of small and medium enterprises. Descriptive statistics and one-way analysis of variance are used to analyse the data. The results show that SMEs receive various types of support to enhance their tax compliance. Further, both secondary and primary data indicate that SMEs have an adequate level of tax compliance. However, there are differences among sectors concerning tax declaration assessment. Based on these results, we discuss and propose several managerial and policy measures to improve SMEs’ tax compliance.Tuân thủ thuế là đề tài nhận được sự quan tâm của nhiều nhà nghiên cứu cũng như các nhà quản lý thuế. Mục tiêu của bài viết này nhằm đánh giá tuân thủ thuế đối với doanh nghiệp thuộc Cục Thuế tỉnh Thừa Thiên Huế quản lý. Trên cơ sở tiếp cận dữ liệu thứ cấp từ cơ quan thuế và thông qua khảo sát từ 362 doanh nghiệp nhỏ và vừa trên địa bàn tỉnh Thừa Thiên Huế, nghiên cứu đã đánh giá tuân thủ thuế của doanh nghiệp nhỏ và vừa thông qua các kỹ thuật thống kê mô tả, phân tích phương sai một yếu tố (ANOVA). Kết quả nghiên cứu cho thấy mức độ tuân thủ thuế của doanh nghiệp nhỏ và vừa là chưa tốt, có sự khác biệt giữa các doanh nghiệp thuộc các lĩnh vực hoạt động khác nhau trong đánh giá về kê khai thuế. Trên cơ sở đó, những hàm ý chính sách quản lý trong việc gia tăng tuân thủ thuế của doanh nghiệp nhỏ và vừa cũng được đề xuất trong bài viết