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A numerical approach for assessing flow compressibility and transonic effect on airfoil aerodynamics
Hoang Thi Bich Ngoc 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
For free Mach numbers M ∞ < 0.65, the standard methods for subsonic potential flows break down when the flow becomes supersonic locally. The transition of the potential equation from elliptic to hyperbolic indicates that the flow changes from a diffusive character to a propagation behavior. The elliptic numerical operators for the subsonic flow will not be able to correctly simulate the propagation properties of supersonic flow regions, which are governed by the equation of hyperbolic type. The presence of local supersonic regions significantly influences the aerodynamic characteristics of airfoil when compared to the predicted results using the standard methods for subsonic flows. To evaluate this transonic effect, the paper presents a method of solving the full potential equation using central and backward finite difference schemes corresponding to the subsonic and supersonic regions. The rotated difference scheme consists in differencing all the derivatives in the normal direction centrally, while the derivatives in the local flow direction are upwind differenced at supersonic points. The transonic effects on airfoil aerodynamics depending on the free Mach number, incidence angle and airfoil geometry were evaluated.
Factors Affecting Activity-Based Costing Adoption in Autonomous Public Universities in Vietnam
HOANG, Thi Bich Ngoc,PHAM, Duc Hieu,NGUYEN, Thi Minh Giang,NGUYEN, Thi Thanh Phuong Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12
The main aim of the present study is to investigate the factors that are considered affecting the adoption of Activity-Based Costing (ABC) in the autonomous public universities in Vietnam. A quantitative research was carried out. The data was collected through an online questionnaire survey between June 2020 and September 2020 addressed to the target respondents comprising 168 managers and accountants from 23 autonomous public universities in Vietnam, which participated in the resolution project No. 77/NQ-CP of the Vietnamese government on the pilot renovation of operational mechanisms of public tertiary education institutions during the period of four years, from 2014 to 2017. The findings resulted from hypothesis testing by a binary regression analysis based on the SPSS 20.0 software show that training, competition, support of top manager, and university size are the four main factors that positively affect the adoption of Activity-Based Costing (ABC) in studied universities. On the other hand, no statistically significant impact was found on two other variables, namely the variety of services provided and the usefulness of cost information factors. From the research results, discussions and policy recommendations have been presented to promote the adoption of Activity-Based Costing (ABC) in Vietnamese autonomous public universities in the coming time.
Hoa Thi Tran,Giang Thu Nguyen,Hong Ha Thi Nguyen,Huyen Thi Tran,Quang Hong Tran,Quang Ho Tran,Ngoc Thi Ninh,Phat Tien Do,Ha Hoang Chu,Ngoc Bich Pham 한국균학회 2022 Mycobiology Vol.50 No.5
Endophytic fungi are promising sources for the production of podophyllotoxin-an important anticancer compound, replacing depleted medical plants. In this study, the endophytes asso- ciated with Dysosma difformis-an ethnomedicinal plant species were isolated to explore novel sources of podophyllotoxin. Fifty-three endophytic fungi were isolated and identified by morphological observation and ITS-based rDNA sequencing, assigning them to 27 genera in 3 divisions. Fusarium was found the most prevalent genus with a colonization frequency of 11.11%, followed by Trametes (9.26%) and Penicillium (7.41%). Phylogenetic trees were constructed for the endophytic fungi community in two collection sites, Ha Giang and Lai Chau, revealing the adaptation of the species to the specific tissues and habitats. Cytotoxic activity of endophytic fungal extracts was investigated on cancer cell lines such as SK-LU-1, HL-60, and HepG2, demonstrating strong anti-cancer activity of six isolates belonging to Penicillium, Trametes, Purpureocillium, Aspergillus, and Ganoderma with IC50 value of lower than 10 mg/mL. The presence of podophyllotoxin was indicated in Penicillium, Trametes, Aspergillus and for the first time in Purpureocillium and Ganoderma via high-performance liquid chromatography, which implied them as a potential source of this anti- cancer compound.
Spectrum of Lysosomal Storage Disease Targeted for Newborn Screening in Vietnam
Dung, Vu Chi,Ngoc, Can Thi Bich,Khanh, Nguyen Ngoc,Mai, Do Thi Thanh,Thao, Bui Phuong,Mai, Tran Thi Chi,Ha, Nguyen Thu,Huong, Nguyen Thi Mai,Nam, Nguyen Hoang,Hai, Le Thanh,Tomatsu, Shunji,Yoo, Han-Wo Association for Research of MPS and Rare Diseases 2017 Journal of mucopolysaccharidosis and rare disease Vol.3 No.1
Nguyen, Ngoc Bich,Cook, Margaret,Johnstone, Kelly,Capra, Mike,Vu, Thi Hoang Lan Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1
Background: In 2013, legislation in Vietnam regulated smoking in public areas. Included was a ban on indoor smoking at universities. Objective: Since awareness and attitude are moderators of the effectiveness of smoke-free policy, ou aim was to assess changes in students' knowledge and attitude tosecond hand smoke (SHS) and awareness and support of smoke-free legislation at four Vietnamese universities, one year after legislative changes. Methods: A two-phase cross sectional study of undergraduate students using self-administered questionnaires (based on the Global Adult Tobacco Survey and the Thrasher survey) was conducted at the introduction of the legislation and one year thereafter. Results: One-year post legislation there were significant increases in knowledge of smoke-free legislation and awareness of universities as smoke-free environments. There was a significant increase in knowledge of harmful effects of SHS on diseases such as examples in the heart and lung, including lung cancer, and miscarriage. Students expressed strong support of smoke-free environments in universities, hospitals, schools, workplaces, public transport, libraries, cinemas and theatres; support was also increased post legislation. Changes were seen in attitude to SHS, and rights of non-smokers and smokers. Conclusions: Positive changes have occurred in knowledge and attitude toward smoke-free environments and SHS in universities since enactment of Vietnamese tobacco control legislation.
Thu Hien Nguyen,Ngoc‑Lan Nguyen,Chi Dung Vu,Can Thi Bich Ngoc,Ngoc Khanh Nguyen,Huy Hoang Nguyen 한국유전학회 2021 Genes & Genomics Vol.43 No.2
Background Primordial dwarfsm (PD) is a group of genetically heterogeneous disorders related to developmental disabilities occurring in the uterus and prolongs during all stages of life, resulting in short stature, facial deformities and abnormal brain. Objective To determine the exact cause of the disease in two Vietnamese patients priory diagnosed with PD by severe preand postnatal growth retardation with marked microcephaly and some bone abnormalities. Methods Whole-exome sequencing was performed for the two patients and mutations in genes related to PD were screened. Sanger sequencing was applied to examine the mutations in the patients of their families. Results Three novel mutations in the PCNT gene which have not been reported previously were identifed in the two patients. Of which, two frameshift mutations (p.Thr479Profs*6 and p.Glu2742Alafs*8) were detected in patient I and one stop-gained mutation (p.Gln1907*) was detected in the patient II. These mutations may result in a truncated PCNT protein, leading to an inactivated PACT domain corresponding to residue His3138–Trp3216 of PCNT protein. Therefore, the three mutations may cause a defciency of protein functional activity and result in the phenotypes of primordial dwarfsm in the two patients. Conclusions Clinical presentations in combination with genetic analyses supported an accurate diagnosis of the two patients with microcephalic osteodysplastic primordial dwarfsm type II (MOPD II). In addition, these results have important implications for prenatal genetic screening and genetic counseling for the families.
Huynh Quoc Vu,Pham Thi Bich Ngoc,Nguyen Le Hoang Thuy To Quyen 사람과세계경영학회 2022 Global Business and Finance Review Vol.27 No.3
Purpose: The purpose of this study is to investigate the impact of formal institutions and their components on productivity spillovers from FDI enterprises to domestic firms’ TFP in developing countries like Vietnam. Design/methodology/approach: The study, conducted in two steps to explore the relationship, is to estimate the firm's TFP in accordance with the semi-parametric method of Levisohn and Petrin (2003). Regression is in accordance with the equation with panel data and adjusted by Driscoll and Kraay standard errors. An unbalanced panel data, related to more than 61,600 Vietnamese manufacturing firms from 2012 to 2017, is combined with the Provincial Institutional Quality Survey (PAPI index) and IO table. Findings: The local institutions have a positive impact on promoting learning ability and increasing productivity of domestic firms, especially small and medium enterprises (SMEs) that take better advantage of this effect. Vertical linkages with FDI enterprises assist local firms to increase productivity while horizontal linkages bring in negative effects. Domestic enterprises with high productivity (in the top 25%) receive positive spillover effects from horizontal linkages and vertical linkages and gain positive impacts of the institution on productivity whereas the group of low-productivity enterprises records negative impacts. This research highlights those enterprises operating in the region where institutions have transparency, accountability, participation in comments and effective corruption control can absorb spillovers and improve their productivity as well as the transparency and corruption control are recognized as having a positive impact through horizontal linkages. Research limitations/implications: With the limitation of research data being conducted only on manufacturing enterprises, there is a lack of data on the impact of service enterprises. The study only stops at understanding the impact of formal institutional effects on productivity spillovers whereas informal institutional effects will be studied in the future. Furthermore, the productivity spillovers of FDI enterprises are explored in general besides other FDI forms that will have different productivity spillovers like offshore. From the results of this study, the governments of developing countries should improve their institutions to encourage local enterprises to take the advantage of spillover effects from FDI enterprises as well as pay more attention to regional factors by supplementing development priority policies based on the capacity of each region. Institutional quality at provincial level has a positive impact on productivity spillovers; consequently, it is essential to have policies for further institutional improvement. Originality/value: This is the first research paper on the impact of the institutional factor at provincial level on firm’s productivity in developing countries like Vietnam. Theoretically, the impact of formal institutions on spillover effects from FDI enterprises is also clarified. In addition, our findings have implications for local economic development policies: vertical linkages promote domestic firms to increase their productivity while horizontal linkages of FDI enterprises in the same industry generate adverse impacts. This paper suggests some feasible solutions for SMEs in developing countries towards their productivity improvement.