A study on emission and fuel consumption of motorcycles in idle mode and the impacts on air quality in Hanoi, Vietnam

Yen-Lien T. Nguyen,Anh-Tuan Le,Khanh Nguyen Duc,Vinh Nguyen Duy,Cong Doan Nguyen 서울시립대학교 도시과학연구원 2021 도시과학국제저널 Vol.25 No.4

This study aims to develop the models of emission and fuel consumption during idling of motorcycles (MCs) in Hanoi, including the unsteady and steady idling stages. Five MC models commonly used in Hanoi were selected to measure the instantaneous emission and fuel consumption rates under the controlled conditions at the laboratory conditions. The instantaneous emission and fuel consumption models during idling were developed for the test MCs in the unsteady idling stage. The R2 of obtained models are higher than 0.9. The average emission and fuel consumption rates in the steady idling stages were determined. The average idling emissions of pollutants CO, CO2, HC and NOx were 60.9, 534.3, 10.3 and 1.8 g/h, respectively. The average fuel loss during idling is around 180 g/h. The emission released from the MC fleet in Hanoi during idling was estimated for the year 2018. The total idling emissions from the MC fleet of 3.9 million vehicles in the year 2018 of CO, CO2, HC and NOx were 6.5, 57.1, 1.1 and 0.2 kt, respectively. The total fuel loss during idling of the MC fleet in 2018 was ∼19.3 kt. The air pollutants eliminated in the idle mode as CO, CO2, HC and NOx contributed 2.23%, 3.19%, 1.14% and 1.03%, respectively, of the total emission from the MC fleet in Hanoi.

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 Effect of Social Capital on Social Entrepreneurial Intention among Vietnamese Students

HA, Ngoc Thang,DOAN, Xuan Hau,VU, Trong Nghia,NGUYEN, Thi Phuong Linh,PHAN, Thanh Hoa,DUONG, Cong Doanh Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.8

This study develops the model to estimate the links between social capital, social entrepreneurial self-efficacy, perceived desirability and social entrepreneurial intention. Besides exploring the direct impacts of social capital, social entrepreneurial self-efficacy, and perceived desirability on social entrepreneurial intention, this study also focus on discovering the mediating roles of perceived desirability and social entrepreneurial self-efficacy on this relationship. Throughout adopting measures from some previous studies, the authors design the questionnaires and distribute to students in Vietnam. The study presents some demographic information of 289 students, who are studying at university and colleges in Vietnam. Then, the validity and reliability of scales are assessed using the value of Cronbach's alpha, Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA). In addition, by utilizing the structural modeling structure (SEM), the authors show that social capital plays the important role in shaping social entrepreneurial self-efficacy, perceived desirability, and social entrepreneurial intention. Interestingly, besides the direct effects on social entrepreneurial intention, perceived desirability and social entrepreneurial self-efficacy also mediate the correlation between social capital and social entrepreneurial intention. Also, with the interesting findings of the study, the authors propose several recommendations for policy-makers, educators and academics to promote the social entrepreneurship and innovation among Vietnamese students.

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.

The first years of liver transplantation: experiences at a single center

Phu Hong Pham,Nghia Phuoc Phan,Viet Doan Khac Tran,Viet Quoc Dang,Thuan Duc Nguyen,Long Cong Duy Tran,Bac Hoang Nguyen 대한이식학회 2022 Korean Journal of Transplantation Vol.36 No.2

Background: The aim of this study was to analyze the first stages of progress in liver transplantation (LT) at a single center in Vietnam. Methods: This study analyzed data from patients and donors who participated in the LT program between August 2018 and December 2021 at University Medical Center, Ho Chi Minh City. Study measures included any difficulties encountered, as well as the post- LT outcomes for living donor LT (LDLT) and deceased donor LT (DDLT). The chi-square test and Kaplan Meier survival analysis were used to test the factors that influenced the outcomes. Results: A total of 18 adult recipients with LT (LDLT, n=16; DDLT, n=2) were included (mean age, 55.2±2.6 years; male, 88.9%). The most common post-LT complications were middle hepatic venous stenosis (20%) and graft rejection (22.2%). These compli- cations were observed in LDLT patients. For DDLT, graft rejection (50%) was the only complication recorded. The survival rates for recipients at 3 months, 6 months, and 1 year were 100%, 88.9%, and 88.9%, respectively. The LDs had their right livers without the middle hepatic veins harvested, and biliary leakage (6.25%) was the only complica- tion observed. There were no deaths among recipients or LDs during the operations or hospital stays. Conclusions: This study provides key details about the process of LT, and these positive outcomes support LT as an important therapy for end-stage liver disease and early he- patocellular carcinomas.

ORiginal Article : The Performance of a Modified Glasgow Blatchford Score in Predicting Clinical Interventions in Patients with Acute Nonvariceal Upper Gastrointestinal Bleeding: A Vietnamese Prospective Multicenter Cohort Study

( Duc Trong Quach ),( Ngoi Huu Dao ),( Minh Cao Dinh ),( Chung Huu Nguyen ),( Linh Xuan Ho ),( Nha Doan Thi Nguyen ),( Quang Dinh Le ),( Cong Minh Hong Vo ),( Sang Kim Le ),( Toru Hiyama ) 대한간학회 2016 Gut and Liver Vol.10 No.3

Background/Aims: To compare the performance of a modified Glasgow Blatchford score (mGBS) to the Glasgow Blatchford score (GBS) and the pre-endoscopic Rockall score (RS) in predicting clinical interventions in Vietnamese patients with acute nonvariceal upper gastrointestinal bleeding (ANVUGIB). Methods: A prospective multicenter cohort study was conducted in five tertiary hospitals from May 2013 to February 2014. The mGBS, GBS, and pre-endoscopic RS scores were prospectively calculated for all patients. The accuracy of mGBS was compared with that of GBS and preendoscopic RS using area under the receiver operating characteristic curve (AUC). Clinical interventions were defined as blood transfusions, endoscopic or radiological intervention, or surgery. Results: There were 395 patients including 128 (32.4%) needing endoscopic treatment, 117 (29.6%) requiring blood transfusion and two (0.5%) needing surgery. In predicting the need for clinical intervention, the mGBS (AUC, 0.707) performed as well as the GBS (AUC, 0.708; p=0.87) and outperformed the pre-endoscopic RS (AUC, 0.594; p<0.001). However, none of these scores effectively excluded the need for endoscopic intervention at a threshold of 0. Conclusions: mGBS performed as well as GBS and better than pre-endoscopic RS for predicting clinical interventions in Vietnamese patients with ANVUGIB. (Gut Liver 2016;10:375- 381)