Preparation and Characterization of Nanocomposites Based on Poly(ethylene-co-vinyl acetate), Polylactic Acid, and TiO₂ Nanoparticles

Do Van Cong,Nguyen Thi Thu Trang,Nguyen Vu Giang,Tran Huu Trung,Nguyen Thuy Chinh,Mai Duc Huynh,Thai Hoang,Jun Seo Park(박준서) 한국고분자학회 2016 폴리머 Vol.40 No.3

This study describes the preparation and characterization of nanocomposites obtained by melt-mixing of poly (ethylene-co-vinyl acetate) (EVA), polylactic acid (PLA), and TiO₂ nanoparticles (TNPs) via three different methods of direct mixing, one-step, and two-step methods. Vinyltrimethoxysilane was used as a surface modifier for the TNPs. The one-step method showed the best suitability for the preparation of EVA/PLA/TiO₂ nanocomposites. The increase in torque and the adhesion of the TNPs with EVA/PLA matrix in these nanocomposites showed enhanced interfacial interactions between EVA, PLA chains, and TNPs. The tensile strength, Young’s modulus, dynamic storage modulus, and thermooxidative stability of the one-step prepared nanocomposites were higher than those of two other nanocomposites and that of the EVA/PLA blend, reaching maximum values at 2.0 wt% of TNPs.

The Role of Zn Doping on the Catalytic Activity of the Nanoparticle Perovskite La0.7Sr0.3MnO3

Tran Thi Minh Nguyet,Nguyen Quang Huan,Tran Que Chi,Do The Chan,Nguyen Doan Thai,Nguyen Cong Trang,Luu Tien Hung,Le Van Tiep,Nguyen Van Qui 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

The nanometer complex oxide La0:7Sr0.3Mn0.6Zn0.₄O₃ was prepared by using a Sol-Gel method with citric acid as a ligand. The in uence of Zn doping of La0.7Sr0.₃MnO₃ on the structure, the morphology, the surface properties and on the catalytic activity of material was studied by using X-ray diraction (XRD), transmission electron microscopy (TEM), a high-resolution images and selected area electron diraction (SAED), physical adsorption and temperature programmed surface reaction (TPSR) methods. The results showed that perovskite La0:7Sr0:3Mn0:6. Zn0.₄O₃ could well catalyse propene oxidation in the temperature range 190 { 280 ℃, which was reduced to 100 { 120 ℃ for catalyst La1-χSrχMnO₃ The nanometer complex oxide La0:7Sr0.3Mn0.6Zn0.₄O₃ was prepared by using a Sol-Gel method with citric acid as a ligand. The in uence of Zn doping of La0.7Sr0.₃MnO₃ on the structure, the morphology, the surface properties and on the catalytic activity of material was studied by using X-ray diraction (XRD), transmission electron microscopy (TEM), a high-resolution images and selected area electron diraction (SAED), physical adsorption and temperature programmed surface reaction (TPSR) methods. The results showed that perovskite La0:7Sr0:3Mn0:6. Zn0.₄O₃ could well catalyse propene oxidation in the temperature range 190 { 280 ℃, which was reduced to 100 { 120 ℃ for catalyst La1-χSrχMnO₃

The Belt and Road Initiative (BRI): Opportunities and Risks from Vietnamese Perspective

Long Duc Bao NGUYEN,Tracy Trang LY,Doan Cong TRAN,Ai Van TRAN,An Quoc LE,Alan HUDSON 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.4

The goal of this research is to look at the Belt and Road Initiative’s (BRI) goals, principles, and priorities, as well as criticisms and concerns. Another goal is to determine the Vietnamese government’s best response to the BRI. Finally, the study looks at the Vietnamese viewpoint. Document review is used in conjunction with PESTELED analysis and EIU country risk model technique in this study. The study is focused on in-depth interviews with 38 top government leaders, researchers, and scholars by adopting the Delphi technique to determine major factors of risks and opportunities as well as obtain a clearer view on the Vietnamese perspective of the BRI. The main conclusion is that Vietnam’s participation in the BRI could result in a variety of benefits and risks, including economic development, connectivity and integration, development finance, cooperation, coordination, trade facilitation, and people-to-people communication, as well as diplomatic and political risks, financial risks, environmental challenges, and job creation. Another conclusion is suggested that careful and case-by-case negotiation with China is needed for Vietnam to exploit the future benefits of BRI. There is a need to set up the strategy to mitigate the risk impacts, reduce the risk level, avoid risk, at last turn the risk into opportunities.

Assessment of Left Ventricular Function and Regional Wall Motion by 256-Slice Dual-Source Coronary CT Angiography: A Comparison With 2D Transthoracic Echocardiography

Le Thi Thuy Lien,Nguyen Khoi Viet,Hoang Van Hoa,Phung Bao Ngoc,Nguyen Ngoc Trang,Vu Thi Kim Thoa,Nguyen Cong Tien,Phan Anh Phuong,Pham Minh Thong,Vu Dang Luu 아시아심장혈관영상의학회 2022 Cardiovascular Imaging Asia Vol.6 No.2

Objective: To compare left ventricular (LV) function, ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), and regional wall motion analyzed in 256-slice dualsource coronary CT angiography (DSCT) with 2D transthoracic echocardiography (TTE). Materials and Methods: One hundred twelve patients suspected of coronary artery disease underwent DSCT and 2D-TTE within one week for LVEF, EDV, and ESV. The correlation between DSCT and 2D-TTE measurements was analyzed through linear regression and Bland- Altman analysis. Regional wall motion was visually scored with a 3-point scale (1, normal; 2, hypokinesia; 3, dysphagia, akinesia). Results: Average LVEF at 66.45%±1.27% (range 23%–85%) as determined on DSCT compared with 66.09%±1.01% (range 25%–84%) on 2D-TTE. LVEF exhibited a good correlation between DSCT and 2D-TTE (r=0.715; p<0.001). Good correlations between DSCT and 2D-TTE were demonstrated for LVEDV (r=0.732; p<0.001) and LVESV (r=0.841; p<0.001). Mean differences (±SD) of 1.78±24.10 mL (p<0.05) and 0.77±13.70 mL (p<0.05) were observed between DSCT and 2D-TTE for LVEDV and LVESV, respectively. LVEF was slightly overestimated with DSCT (0.52%±9.59%; p<0.05). Although the LVEF values calculated by DSCT and 2D-TTE were similar, EDV and ESV from DSCT were statistically higher than those from 2D-TTE (p<0.05). Agreement between DSCT and 2D-TTE in regional wall motion was 96.4%, κ=0.840. Conclusion: DSCT can provide comparable results to those using 2D-TTE for LV function (EF, EDV, and ESV) and regional wall motion assessment in a heterogeneous population.

Preparation of Gold Nanoparticles, Au/Fe2O3 by Using a Co-Precipitation Method and their Catalytic Activity

Tran Thi Minh Nguyet,Nguyen Cong Trang,Nguyen Quang Huan,Nguyen Xuan,Luu Tien Hung,Masakazu Date 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Au=Fe₂O₃(Au : Fe = 1 : 50) catalyst was prepared by the co-precipitation method. The co- precipitate was studied by using dierential thermal analysis (DTA) and dierential thermal gravi- metric analysis (DTGA). The structure of the sample was investigated by using X-ray diraction (XRD) and transmission electron microscopy (TEM) and high-resolution transmission electron mi- croscopy (HRTEM). The particle size was determined to be within the range of 1.5 and 8 nm. Results of the study for catalytic properties showed that T1=2 for CO and H2 oxidation were 317 and 405 K respectively. Au=Fe₂O₃(Au : Fe = 1 : 50) catalyst was prepared by the co-precipitation method. The co-precipitate was studied by using DTA and DTGA. The structure of the sample was investigated by XRD, TEM and HRTEM. The particle size was determined to be within the range of 1.5 and 8 nm. Results of the study for catalytic properties showed that T1=2 for CO and H2 oxidation were 317 and 405 K respectively. Au=Fe₂O₃(Au : Fe = 1 : 50) catalyst was prepared by the co-precipitation method. The co- precipitate was studied by using dierential thermal analysis (DTA) and dierential thermal gravi- metric analysis (DTGA). The structure of the sample was investigated by using X-ray diraction (XRD) and transmission electron microscopy (TEM) and high-resolution transmission electron mi- croscopy (HRTEM). The particle size was determined to be within the range of 1.5 and 8 nm. Results of the study for catalytic properties showed that T1=2 for CO and H2 oxidation were 317 and 405 K respectively. Au=Fe₂O₃(Au : Fe = 1 : 50) catalyst was prepared by the co-precipitation method. The co-precipitate was studied by using DTA and DTGA. The structure of the sample was investigated by XRD, TEM and HRTEM. The particle size was determined to be within the range of 1.5 and 8 nm. Results of the study for catalytic properties showed that T1=2 for CO and H2 oxidation were 317 and 405 K respectively.

The Impact of Capital Structure on Firm’s Profitability: A Case Study of the Rubber Industry in Vietnam

Huong Thi Thanh CO,Trang Thi Mai UONG,Cong Van NGUYEN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.7

This study aims to examine and measure the impact of capital structure on the profitability of companies in emerging markets. The research sample includes eighteen rubber companies listed on the Vietnam stock exchange from 2015–2019. After collecting the research data, it was imported into excel to calculate the criteria for the research model. By using Stata 16 software, the study selected a data processing model and evaluated the relevance of the regression analysis model. The research results show that the profitability of listed rubber companies in Vietnam (measured by return on equity (ROE) has a positive relationship with the debt-to-asset ratio but has a negative relationship with the long-term debt-to-asset ratio. The results also show a positive impact of firm size and revenue growth on profitability while liquidity and the ratio of tangible fixed assets to total assets do not affect significantly. These results are consistent with most of the previously published studies. However, in contrast to many previous studies, our study shows that the long-term debt-to-assets ratio has a negative effect on profitability while the debt-to-asset ratio has a positive effect. This is entirely consistent with the characteristics of long-term debt use in emerging markets.

Aerodynamic drag of axisymmetric models with different boattail angles under subsonic and supersonic flow conditions

The Hung Tran,Cong Truong Dao,Dinh Anh Le,Van Khiem Pham,Van Minh Do,Trang Minh Nguyen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

This study examines the drag trend and flow behavior of axisymmetric models with conical boattails under subsonic and supersonic conditions by using a numerical approach. Mach numbers ranging from 0.1 to 3.0 and boattail angles varying from 0° to 24° are investigated. The numerical results are validated by experimental data under identical flow conditions. The flow behavior around the boattail body, the total drag, and the pressure distribution are analyzed in detail. The drag components acting on the boattail surface are examined to determine the reason for the change in drag due to different boattail angles and Mach number conditions. Results show that the minimum drag is around 14° for subsonic flow, but this value suddenly decreases to around 7° for supersonic flow. Formalization of the expansion and oblique shocks on the boattail is the main cause of changes in the pressure distribution on the surfaces, which in turn affect the drag trend. Moreover, the relationships among boattail angle, flow conditions, and four flow types on the boattail surface are presented in detail.

Additive biocomponents from catfish by-products enhance the growth of shrimp Litopenaeus vannamei

Pham Viet Nam,Tran Vy Hich,Nguyen Van Hoa,Khuong V. Dinh,Nguyen Cong Minh,Trang Si Trung 한국수산과학회 2023 Fisheries and Aquatic Sciences Vol.26 No.6

The rapid expansion of shrimp production requires a huge amount of protein sources from soybeans and wild-caught fishmeal; both are becoming a shortage. Meanwhile, catfish production and processing is a giant industry in Vietnam, which produce hundred thousand tonnes of protein- and lipid-rich by-products, annually. Using catfish by-products to gradually replace the traditional protein sources in shrimp aquaculture may bring triple benefits: 1) reducing pressure on wild fish exploitation for fishmeal, 2) reducing the environmental impacts of catfish by-products, and 3) increasing the value and sustainability of aquaculture production. In this study, we used catfish by-products to produce fish protein hydrolysate (FPH) and nano-hydroxyapatite (HA) as additives in feed for Pacific white shrimp (Litopenaeus vannamei). The supplement mixture of FPH and HA was added into the commercial diet (Charoen Pokphand Group [CP], 38% protein, and 6.5% lipid) to reach 38%, 38.5%, 40%, 43%, and 44% of the crude protein content. The survival and growth of shrimps were weekly assessed to day 55. The results showed that the shrimp growth was highest at 43% crude protein content in the feed as indicated by an increase of 124% and 112% in shrimp weight and length, respectively, compared to the commercial reference diet. No negative effects of adding the mixture of FPH and HA on the water quality were observed. Vibrio density was lower than 6.5 × 103 CFU/mL, which is the lowest Vibrio density negatively affecting the shrimp growth and development. These findings indicate that the mixture of FPH and HA are promising additive components in feed for post-larval shrimp L. vannamei diets.