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

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

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

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

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

Dry Eyes Status on Des Scale and Related Factors in Outpatients at Vietnam National Institute of Ophthalmology

BACKGROUND: Dry eye (DE) can effect on quality of life by pain, inability to perform certain activities that require prolonged attention (driving, reading,…) and productivity at work and finally effect to Q0L associated with DE. OSDI is scale questionnaire is created team to measure the quality of life related to ocular surface disease. AIM: To describe the dry eye disease according to OSDI scale and related factors of this disease. METHODS: A cross-sectional descriptive study was carried out on outpatients (≥ 16-year-old) who were examined and diagnosed with dry eyes at Vietnam National Institute Of Ophthalmology from April to July 2018. Data was collected using the OSDI questionnaire. RESULTS: The average age of participants was 44.6 years; 80.9% of patients were female; 39.9% were identified having mild dry eye. The related factors have been identified that associated with severe dry eye, including age OR = 1.03 (95%CI: 1.01-1.05, p = 0.005), binocular good vision OR = 0.11 (95%CI: 0.05-0.23; p < 0.0001), medical history OR = 17.09 (95%CI: 2.24-130.25; p < 0.0001), chronic conjunctivitis OR = 0.36 (95%CI: 0.14-0.91; p = 0.027), refractive errors OR = 0.14 (95%CI: 0.04-0.48; p < 0.0001), Sjogren's syndrome OR = 31.13 (95%CI: 7.08-136.76; p < 0.0001). CONCLUSION: Several related factors have been identified associated with severe dry eye, including: age, binocular good vision, medical history, chronic conjunctivitis, refractive errors, Sjogren's syndrome

Indigenous knowledge in climate change adaptation: Case studies of ethnic minorities in the Northern Mountain Region of Vietnam

This study aims to investigate the indigenous knowledge (IK) of three ethnic minority groups in the Northern Mountain Region (NMR) of Vietnam. The groups include (1) Tay people who live at lower elevations; (2) a Dao community who tend to live in the middle elevations and (3) Hmong farmers who mainly reside at higher elevations areas of the mountain. This research intends to identify climate change (CC) and its impact on agricultural cultivation and find out how these groups can adapt to CC by applying their IK in agriculture practices. Data was collected through focus group discussions (n=9), in-depth interviews (n=80), and participant observation. From the 80 respondents, 27 live in Bac Kan province, 23 in Yen Bai province and 30 in Son La province; those who had experience in agricultural production, elderly and village heads. The results show that the NMR weather has significant changes that negatively impact agriculture cultivation and local livelihood. Although the respondents are from different ethnic minorities, these farmers are highly aware of the CC risks, leading into adaptation practices. While the Tay people's major adaptation strategies include the use of a variety of native plants and changing planting calendars, the Dao and Hmong people apply intercropping and local techniques methods in terracing fields using local varieties of livestock. Our findings highlight the importance of using the IK of ethnic minorities in adaptation towards CC. A better targeting about the use of local resources in future national policies and projects is encouraged.Nghiên cứu này nhằm thu thập kiến thức bản địa (IK) của ba nhóm dân tộc thiểu số ở Miền núi phía Bắc (MNPB) của Việt Nam bao gồm (1) dân tộc Tày chủ yếu sống ở vùng thấp; (2) Người Dao có xu hướng sống ở các độ cao trung bình; và (3) người Hmông chủ yếu cư trú ở các khu vực đồi núi cao. Nghiên cứu này nhằm xác định tình hình biến đổi khí hậu (BĐKH) và tác động của nó đối với sản xuất nông nghiệp, đồng thời tìm hiểu cách thức các nhóm dân tộc thiểu số này có thể thích ứng với BĐKH bằng cách áp dụng các kiến thức bản địa của họ vào thực tiễn sản xuất nông nghiệp. Dữ liệu được thu thập thông qua thảo luận nhóm tập trung (n = 9), phỏng vấn sâu (n = 80) và quan sát người tham gia. Trong số 80 người được hỏi, có 27 người sống ở tỉnh Bắc Kạn; 23 người ở tỉnh Yên Bái và 30 người ở tỉnh Sơn La, là những người có kinh nghiệm sản xuất nông nghiệp, người cao tuổi và trưởng thôn. Kết quả cho thấy thời tiết ở khu vực MNPB đã có những thay đổi so với trước gây tác động xấu đến canh tác nông nghiệp và sinh kế của cộng đồng. Mặc dù những người được hỏi từ các dân tộc khác nhau nhưng họ đều nhận thức được sự thay đổi này của thời tiết, do đó họ đã có những thích ứng riêng. Trong khi người Tày sử dụng giống cây trồng địa phương và thay đổi lịch thời vụ thì người Dao và Hmong chọn phương pháp xen canh và áp dụng kỹ thuật bản địa trên đất ruộng bậc thang và sử dụng gióng vật nuôi bản địa. Các phát hiện của chúng tôi giúp hiểu được tầm quan trọng của việc sử dụng IK trong thích ứng với BĐKH của các dân tộc thiểu số, từ đó có thể hướng đến mục tiêu tốt hơn việc sử dụng các nguồn lực địa phương trong các chính sách và dự án quốc gia trong tương lai

PSSA- INTERNATIONAL SOLUTION TO PROTECT THE BIODIVERSITY IN HA LONG BAY - CAT BA MARINE AREA

A Particularly Sensitive Sea Area (PSSA) is an important management tool for biodiversity protection of a marine area. At the time of designation of a Particularly Sensitive Sea Area, an associated protective measure, which meets the requirements of the appropriate legal instrument establishing such measure, must have been approved or adopted by IMO to prevent, reduce, or eliminate the threat or identified vulnerability. Information on each of the Particularly Sensitive Sea Areas (PSSAs) that has been designated by IMO is available on the nautical chart. The Vietnam’s coastal zones and islands are the isolated oceanic habitat of extremely rich marine life in very good condition which is important to the maintenance and dispersal of the marine life of the western tropical Pacific. Vietnam coastal areas are very high risk areas affected by maritime activities, particularly international shipping, therefore in the future identification of some Particularly Sensitive Sea Areas (PSSAs) is necessary. The first Particularly Sensitive Sea Area for Vietnam in Ha Long - Cat Ba was initially proposed in this paper