What explains Vietnam's exceptional performance in education relative to other countries? Analysis of the 2012, 2015, and 2018 PISA Data

Despite being the poorest or second poorest participant, Vietnam outperformed all other developing countries, and many wealthier countries, on the 2012, 2015, and 2018 PISA assessments. We investigate Vietnam's strong performance, evaluating several possible explanations for this apparent exemplary achievement. After correcting for potentially non-representative PISA samples, including bias from Vietnam's large out-of-school population, Vietnam remains a large positive outlier conditional on its income. Possible higher motivation of, and coaching given to, Vietnamese students can at most only partly explain Vietnam's performance. The child-, household- and school-level variables in the PISA data explain little of Vietnam's strong PISA performance relative to its income level. At most, they explain about 30% of Vietnam's exceptional performance in math and reading. Further research is needed to understand the exceptional performance of Vietnamese students

Evaluation of Anterior Chamber Depth and Anterior Chamber Angle Changing After Phacoemulsification in the Primary Angle Close Suspect Eyes

BACKGROUND: Phacoemulsification surgery has the ability to deeply alter the segment anterior morphology, especially in eye with shallow anterior chamber (AC), narrow anterior chamber angle (ACA). However, the changes of anterior chamber depth (ACD) and ACA on the close angle suspect eyes after phacoemulsification have not been mentioned in many studies. So, we conduct this research. AIM: To evaluate the alteration in the ACA and ACD after phacoemulsification in the close angle suspect eyes. METHODS: Interventional study with no control group. Subjects were the primary angle closure suspect (PACS) eyes, that were operated by phacoemulsification with intraocular lens (IOL) at Glaucoma Department of VNIO from December 2017 to October 2018. RESULTS: 29 PACS eyes with cataract were operated by phacoemulsification with intraocular lens. After 3 months of monitoring, the average ACD augmented from 2.082 ± 0.244 to 3.673 ± 0.222 mm. AOD500 increase from 0.183 ± 0.088 to 0.388 ± 0.132 μm, AOD750 increased from 0.278 ± 0.105 to 0.576 ± 0.149 μm. The TISA500 enlarged from 0.068 ± 0.033 to 0.140 ± 0.052 mm2, TISA750 enlarged from 0.125 ± 0.052 to 0.256 ± 0.089 mm2 at the third month (p < 0.01). CONCLUSION: Phacoemulsification surgery increases the ACD and enlarged the angle in the PACS eyes

Effect of deposition time on gold nanodendrite porous structure and on signals of Hg(II) in environment

The influences of deposition time (tdep) for Au nanodendrite preparation on carbon cloth electrodes on the surface structure, electrochemical behavior and voltammetric signal for Hg(II) detection have been studied. The obtained results showed that from 60 s to 300 s, the longer deposition time, the larger dendrite length as well as the more increased density of dendrite structure became. Calculated from data showed that the electroactive surface area approached to the maximum value of 3.686 cm2 with tdep = 300 s. The typical electrochemical behaviour of the prepared electrodes was mass transfer diffusion to the electrode surface and being considered as planar diffusion. Using DPASV technique, the peak height of Hg(II) could appoach to 52 µA with tdep = 60 s. Keywords. Gold nanodendrite, deposition time, surface structure, electrochemical properties, mercury

LOẠI BỎ XANH METYLEN BẰNG PHƯƠNG PHÁP ĐIỆN DI LẮNG ĐỌNG KẾT HỢP VỚI VẬT LIỆU MnO2/GO

Graphene oxide (GO) was synthesized with the improved Hummer method and chemically modified with manganese dioxide (MnO2) to obtain an MnO2/GO composite. The properties of the composite material were evaluated via infrared spectroscopy, UV-Vis spectroscopy, scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, and image mapping. The parameters studied in the method of electrophoretic deposition (EPD) are pH, electrolysis potential, electrolysis time, sodium chloride concentration, and the mass of the composite. Under suitable experimental conditions, the EPD method provides a rate of colour removal and chemical oxygen demand (COD) of methylene at 99.64 and 85.85%. This result shows the potential of the EPD method coupled with MnO2/GO composite to remove organic pigments in the aqueous medium.Vật liệu graphen oxit (GO) được tổng hợp bằng phương pháp Hummer cải tiến và biến tính với mangan đioxit (MnO2) bằng phương pháp hóa học để thu được vật liệu tổ hợp MnO2/GO. Một số tính chất đặc trưng của vật liệu tổ hợp được đánh giá bằng phổ hồng ngoại, phổ UV-Vis, hiển vi điện tử quét kết hợp với quang phổ tán xạ năng lượng tia X và ảnh mapping. Các thông số trong phương pháp điện di lắng đọng (EPD) như pH, thế điện phân, thời gian điện phân, nồng độ clorua natri và khối lượng vật liệu tổ hợp đã được nghiên cứu. Vật liệu MnO2/GO có khả năng loại màu và nhu cầu oxy hóa học của xanh metylen với hiệu suất 99,64 và 85,85% với phương pháp EPD. Kết quả cho thấy tiềm năng của của phương pháp EPD kết hợp với vật liệu MnO2/GO để loại bỏ chất màu hữu cơ trong môi trường nước

THE SHELF-LIFE OF BLACK TIGER SHRIMP (PENAEUS MONODON) TREATED WITH THE DIFFERENT CONDITIONS

This study examines the chemical and microbiological changes and the sensory attributes of black tiger shrimp (Penaeus monodon) when stored at the temperature of 0 ºC. Sodium propionate and sodium lactate were used to treat shrimps before storage. Vacuum packaging was also carefully investigated. Throughout storage, the quality indicates including TVB-N, TMA-N, histamine, quality index (QI) and total viable count (TVC) were used to evaluate the quality changes of shrimp. The results show that though with different rates, the increase in quality indicators caused the decrease in the quality of shrimp during storage. The quality of shrimps treated with salts of organic acids or those packed in the vacuum bags was significantly higher than that of the control. In particular, the shelf-life of the sample packed in the vacuum packages was twelve days, which was four days longer than that of the control

Speed profile optimization of an electrified train in Cat Linh-Ha Dong metro line based on pontryagin's maximum principle

An urban railway is a complex technical system that consumes large amounts of energy, but this means of transportation still has been obtained more and more popularity in densely populated cities because of its features of high-capacity transportation capability, high speed, security, punctuality, lower emission, reduction of traffic congestion. The improved energy consumption and environment are two of the main objectives for future transportation. Electrified trains can meet these objectives by the recuperation and reuse of regenerative braking energy and by the energy - efficient operation. Two methods are to enhance energy efficiency: one is to improve technology (e.g., using energy storage system, reversible or active substations to recuperate regenerative braking energy, replacing traction electric motors  by energy-efficient traction system as permanent magnet electrical motors; train's mass reduction by lightweight material mass...); the other is to improve operational procedures (e.g. energy efficient driving including: eco-driving; speed profile optimization; Driving Advice System (DAS); Automatic Train Operation (ATO); traffic management optimization...). Among a lot of above solutions for saving energy, which one is suitable for current conditions of metro lines in Vietnam. The paper proposes the optimization method based on Pontryagin's Maximum Principle (PMP) to find the optimal speed profile for electrified train of Cat Linh-Ha Dong metro line, Vietnam in an effort to minimize the train operation energy consumption

Impairment of Assets Under Perspectives of International and Vietnamese Accounting

This study investigates the impairment of assets on financial reportings of three separate entities - Vietnam Prosperity Joint-Stock Commercial Bank (VPBank), The Bank of East Asia (BEA) and The Nestlé Group - in the financial year of 2017. By bringing out the differences between international accounting system of asset impairment (IAS 36) and Vietnamese accounting system (VAS), this research has determined the gap between two sets of financial statements under IFRS and VAS in conveying the business performance and financial position. The empirical results show Vietnam’s necessary for a convergence in asset impairment with international accounting system. Therefore, we provide some recommendations for Vietnam in applying asset impairment regarding to IAS 36 partly or completely. Keywords: Asset impairment, International accounting, Vietnamese accounting. DOI: 10.7176/RJFA/10-12-07 Publication date:June 30th 2019

A Research on the Quality of Public Transportation Services by Bus in Vietnam

This study was conducted to assess the status of the quality of public passenger transport services by bus in Hanoi. Data were collected from regular passengers using buses as a means of transportation in the city, including passengers standing at stations, waiting shelters and on vehicles to make trips and students of some universities who use buses as a means of transportation. We employ descriptive statistics and hierarchical analysis to learn about the topic of research. The results indicate that the quality of public transport services by buses in Hanoi, which was judged by passengers quite well. In particular, the safety level, convenience, security and hygiene is up to 70%, which was higher than the highest quality level. Quality of fast level and reliability are low. Keywords: quality of services, public passenger transport, buses, Vietnam. DOI: 10.7176/RJFA/10-13-04 Publication date:July 31st 201