bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF CO-DOPED RARE-EARTH AND TRANSITION-METAL IONS ON STRUCTURAL, OPTICAL AND MAGNETIC PROPERTIES OF BiFeO3 MATERIAL
Authors: Thang Dao Viet
Published: April 2018

Structural, optical and magnetic properties of polycrystalline BiFeO3 and Bi0.9RE0.1Fe0.95Ni0.05O3 (RE = Sm, Y, Nd) prepared by sol–gel method have been investigated. X-ray diffraction (XRD) patterns reveal that all samples crystalize in rhombohedrally distorted perovskite structure belonging to space group R3c. Analyzed results of both XRD and Raman scattering data show an increase of lattice distortion with co-replacing of rare earths and nickel atoms into Bi and Fe sites respectively. All samples exhibit a weak ferromagnetic behavior at room temperature with enhancement of the magnetization of RE and Ni co-doped samples.
INFLUENCE OF SINTERING TEMPERATURE ON PHASE FORMATION AND OPTICAL PROPERTIES OF LEAD-FREE FERROELECTRIC BI0.5NA0.5TIO3 MATERIALS
Authors: Hai Thanh Le Thi
Published: April 2018

Pb(Zr,Ti)O3 based ferroelectric materials have been widely used in electronic devices even though they were banned due to the toxicity of lead on health and environment. Among the lead-free ferromagnetic materials, Bi0.5Na0.5TiO3 has received much attention because their ferroelectric and piezoelectric characteristics are comparable to Pb(Zr,Ti)O3. In this report, Bi0.5Na0.5TiO3 was fabricated by sol-gel method. The influence of fabricating conditions such as gelization, sintering temperature on crystallinity was studied. The result showed that Bi0.5Na0.5TiO3 was in single phase when compenstation amount of Na in gelization is 40 mol%; sintering temperature higher than 800 oC and sintering time is 2 h. The bandgap of Bi0.5Na0.5TiO3 which estimated from absorption spectroscopy is in the range of 3.01 - 3.18 eV.
SYNTHESIS AND INVESTIGATION SOME PROPERTIES OF WO3 ELECTROCHROMIC THIN FILMS
Authors: Thien Nguyen Duy
Published: April 2018

The study of electrochromic thin films, which are transparent in the visible range, is significantly important in producing smart doors production and saving energy. This paper reports the results of preparing WO3 thin films on glass substrates and ITO substrates by thermal vacuum evaporation method. The influence of annealing temperature on the properties of thin films was investigated by X-ray diffraction, Raman scattering spectroscopy, X-ray energy dispersive spectroscopy, Atomic force microscopy and absorption and transmittance UV–vis spectroscopy. The results show that WO3 thin films have a high transmittance of about 90% in the visible wavelength from 400 to 900 nm, good substrate adhesion. The WO3 thin films were crystallized at 400 oC and the crystallization of thin films on the ITO substrate better than glass substrate. Electrochromic characteristics of WO3 thin films were investigated by Autolab electrochemical system. The results show the transmittance of WO3 thin film was reduced to around 12 % in visible region when increasing the applied voltage from - 0.1 V to - 0.7 V. The transmittance of the film was completely recovered by using an applied voltage of 2 V.
NGHIÊN CỨU ĐỘ BỀN VÀ TÍNH CHẤT CỦA VẬT LIỆU KHUNG CƠ KIM Zr-MOF TRONG NƢỚC ĐỊNH HƢỚNG CHO ỨNG DỤNG HẤP PHỤ KHÍ
Authors: Thu Phùng Thị
Published: April 2018

Vật liệu khung cơ kim Zr-MOF được tổng hợp từ phản ứng giữa muối zirconium clorua với axit benzene 1,4-dicarboxylate bằng phương pháp thuỷ nhiệt ở nhiệt độ 120 oC trong 36 giờ. Vật liệu này được nghiên cứu chế tạo trong dung môi N, N-dimethyformamide (DMF). Sau đó, sản phẩm thu được được ngâm trong môi trường nước ở nhiệt độ thường và 100 oC để nghiên cứu độ bền của vật liệu theo thời gian. Cấu trúc tinh thể, hình thái học và diện tích bề mặt của vật liệu được xác định qua giản đồ nhiễu xạ tia X, hiển vi điện tử quét phân giải cao (FESEM) và thiết bị đo BET cho thấy vật liệu có cấu trúc hình lập phương. Độ bền nhiệt của vật liệu được đo bằng phương pháp phân tích nhiệt trọng lượng (TGA). Các phép đo cho thấy UiO-66 có độ tinh thể cao, độ bền nhiệt đạt 809 K và không bị phá hủy khi ngâm trong nước.
STUDY ON ITO THIN FILMS PREPARED BY MULTI-ANNEALING TECHNIQUE
Authors: Hoa Nguyen Quang
Published: April 2018

Indium tin oxide (ITO) thin films have been successfully prepared by a solution process followed by a multi-annealing method. In this study, we focus on the use of multi-annealing method, for which each layer was annealed at a suitable temperature, instead of a conventional annealing way, by means of a rapid thermal annealing system, in order to improve the film quality. The crystalline structure and surface morphology of the ITO thin films were investigated by using X-ray diffraction (XRD) spectrometer, atomic force microscope (AFM) and scanning electron microscope (SEM). It has been obtained that all of ITO films exhibit a single phase with (222)- and (440)-preferred orientations. The AFM and SEM observations show that the particle size of ITO films was about 10 nm and the ITO film thickness was 180 nm, respectively. In sequence, the electrical properties of ITO thin films were evaluated by using four-point probe and Hall effect measurement methods, and the optical properties were investigated by UV/VIS spectrometer. The results show that the best ITO films have electrical resistivity of 2.6 × 10-3 Ω.cm and transparency higher than 90 %, which strongly supports to the application of electrode in solar cell, LED or transistor devices from viewpoints of low-cost production and low-energy consumption.
DEPOSITION OF HIGH-ELECTRON-MOBILITY TRANSPARENT CONDUCTING ALUMINUM-DOPED ZINC OXIDE THIN FILMS BY DC MAGNETRON SPUTTERING
Authors: Dung Hoang Van
Published: April 2018

Transparent conducting Al-doped ZnO (AZO) thin films were deposited on glass substrates by DC magnetron sputtering from AZO ceramic target (0.75 %wt Al2O3) in gas mixture of (Ar + H2) at different substrate temperatures. At value of 1.7 % of ratio of H2 to (H2+Ar) and at substrate temperature of 200 oC, electron mobility in obtained AZO films is 60.2 cm2.V-1.s-1, which is much larger than 34.6 cm2.V-1.s-1 of films fabricated in the same condition without H2. AZO films also have a low resistivity of 2.53×10-4 Ω.cm, low sheet resistance of 2.5 Ω/□ and high average transmittance above 80 % in the wavelength range of 400 – 1100 nm.
SYNTHESIS AND APPLICATION OF GRAPHENE/SILVER NANOWIRES/GOLD NANOPARTICLES HYBRID FOR AMMONIA GAS SENSING
Authors: Hoa Huynh Tran My
Published: April 2018

Graphene material synthesized from chemical method (reduced Graphene Oxide – rGO) is a promising candidate for gas sensors due to their unique properties. With structure of single layer of bonded sp2 carbons in a two-dimensional (2D) lattice, rGO have large surface to volume ratio, high conductivity and electron mobility at room temperature. Meanwhile, the different oxygen-containing functional groups (contain dangling bonds) decorated on carbon networks make rGO easily respond with compatible gas molecules. However, the investigating of structure of rGO in micrometer scale shows that the chemical method often results in non-uniform film thickness on substrate due to overlap of rGO sheets. These may disrupt the conductive paths in rGO films and decrease their conductivity. Therefore, gas sensing signal of pristine rGO based sensors is tarnished and the sensors do not recover to their baseline at room temperature. In this study, silver nanowires (AgNWs) and gold nanoparticles (AuNPs) are combined with rGO material to form rGO/AgNWs/AuNPs hybrid. With one-dimensional nanostructure, the AgNWs connects effectively together many rGO islands and reduce significantly their contact resistance so that NH3 sensing signal is improved and complete recovery of the sensor is nearly achieved at room temperature. Especially, all these signals are further enhanced when the AuNPs (diameter ~ 30 nm) are added into the hybrid.
CẤU TRÚC VÀ TÍNH CHẤT QUANG CỦA NANO TINH THỂ BÁN DẪN ZnxCd1-xS
Authors: Lan Hương Hoàng Thị
Published: April 2018

Độ rộng vùng cấm của các nano tinh thể (NC) hợp kim có thể thay đổi được thông qua thay đổi kích thước và thành phần của chúng. Trong bài báo này, chúng tôi đã tổng hợp và khảo sát cấu trúc pha tinh thể của các NC ZnxCd1-xS có phân bố các nguyên tố hóa học đồng đều khi tỉ lệ Zn/Cd thay đổi. Các NC ZnxCd1-xS được tổng hợp từ zinc stearate, cadmium stearate và lưu huỳnh, trong môi trường phản ứng octadecene, tại nhiệt độ 280 ºC bằng phương pháp hóa ướt. Đây là cách chế tạo đơn giản, chi phí thấp và có độ lặp lại cao nhưng rất khó để nhận được nano tinh thể ZnxCd1-xS có phân bố các nguyên tố hóa học đồng đều do hoạt tính hóa học khác nhau của các tiền chất Zn và Cd. Cấu trúc và hằng số mạng của NC ZnxCd1-xS được làm rõ bởi giản đồ nhiễu xạ tia X, thành phần và hàm lượng của các nguyên tố hóa học trong hợp kim được xác định bởi phương pháp phân tích phổ tia X, sử dụng phổ kế tán sắc năng lượng (EDS), tính chất quang của các NC ZnxCd1-xS được nghiên cứu bởi phổ hấp thụ và quang huỳnh quang.
EFFECT OF ANNEALED TEMPERATURE ON NO2 GAS-SENSING PERFORMANCES OF SnO2 NANOWIRE SENSORS
Authors: Trung Do Dang
Published: April 2018

NO2 gas is a highly toxic gas and emitted from vehicles such as motocycles and internal engine transportations. It is one of the major reasons which cause air pollution in recent years, especially in big cities. Therefore, the development of NO2 gas sensor for environmental monitoring has been gained research attention in the global. In this work, we report a simple and effective method to prepare SnO2 nanowire gas sensors. The SnO2 nanowires were directly grown on the unplosihed Al2O3 substrate equipped with a pair of Pt-electrodes. The morphology and microstructure of as-grown nanowires have been investigated via X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transimission electron microscopy (TEM). The results indicated that the diameters and lengths of nanowires are about 60 – 100 nm and tens of μm, respectively. The gas-sensing performance of the SnO2 nanowires sensors annealed at different temperatures have also investigated. The results revealed that the annealed temperatures of 400 C and 500 oC do not affected on gas-sensing performance of SnO2 nanowires sensors, while the annealed temperature of 600oC results in strong decrease in NO2 gas response as compared with as-grown SnO2 nanowires sensor.
TỔNG HỢP BỘT HUỲNH QUANG Y3Al5O12: Eu (III) PHÁT XẠ ÁNH SÁNG ĐỎ XA BẰNG PHƢƠNG PHÁP ĐỒNG KẾT TỦA
Authors: Thư Lê Diệu
Published: April 2018

Bột huỳnh quang (Y0.93Eu0.07)3Al5O12 đã được tổng hợp thành công theo phương pháp đồng kết tủa với tác nhân tạo kết tủa là NH3.H2O . Các kết quả phân tích phổ nhiễu xa tia X (XRD) chỉ ra mẫu thu được là đơn pha với sự Hình thành tinh thể diễn ra ở khoảng 1000 ºC trong 3 giờ, không có sự xuất hiện các đỉnh nhiễu xạ đặc trưng cho các pha trung gian của mạng nền YAG cũng như các đỉnh nhiễu xạ liên quan đến các pha của tạp chất tạo ra. Các kết quả phân tích phổ huỳnh quang (PL) cho thấy, có 4 dải phát xạ đặc trưng trong vùng đỏ từ 570 – 720 nm với các đỉnh là 592 nm, 598 nm, 611 nm và 710 nm. Sự xuất hiện đỉnh phát xạ có cực đại tại 710 nm với cường độ huỳnh quang nổi trội tương ứng với khả năng phát xạ trong vùng ánh sáng đỏ xa (infared) cho thấy tiềm năng ứng dụng của loại vật liệu này trong chế tạo các thiết bị chiếu sáng sử dụng trong chiếu sáng nông-ngư nghiệp công nghệ cao.
PREPARATION AND CHARACTERIZATION OF SIO2/POLY(METHYL METHACRYLATE) CORE/SHELL NANOCOMPOSITES VIA RAFT POLYMERIZATION
Authors: Bach Long Giang
Published: April 2018

This article describes the fabrication of SiO2 nanoparticles grafted with poly(methyl methacrylate) (PMMA) via a fascinating reversible addition-fragmentation chain transfer (RAFT) polymerization by adopting “grafting from” approach. The silane coupling agent, S-benzyl S’-trimethoxysilylpropyltrithiocarbonate, was anchored onto SiO2 nanoparticles in a simple procedure using a ligand exchange reaction. RAFT agents-anchored SiO2 nanoparticles were then used for the surface-initiated RAFT polymerization of MMA to fabricate structurally well-defined, core-shell SiO2-g-PMMA nanocomposites. The structure and properties of the as-synthesized nanocomposites were investigated by Fourier Transformed Infrared Spectrophotometry (FT-IR), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric analysis (TGA), Field Emission Scanning Electron Microscopy (FE-SEM).
CONSTRUCTING POLYSTYRENE BRUSHES ON TIO2 NANOPARTICLES BY IN SITU REVERSIBLE ADDITION FRAGMENTATION CHAIN TRANSFER POLYMERIZATION
Authors: Bach Long Giang
Published: April 2018

This paper presents the preparation of polystyrene functionalized TiO2 nanoparticles using the reversible addition fragmentation chain transfer (RAFT) polymerization. The surface of TiO2 NPs with an average particle size of about 5 nm was modified by S-benzyl S’-trimethoxysilylpropyltrithiocarbonate in order to obtain the RAFT agent functionalized TiO2 NPs (TiO2-RAFT). Subsequently, styrene was radically polymerized through the immobilized RAFT agent on the silica surface, in the presence of 2,2’-azobisisobutylnitrile (AIBN) as an initiator, to achieve the TiO2-g-PS nanocomposite. The characteristics of the as-synthesized nanocomposite were determined using FT-IR, EDX, XPS, TGA, XRD, TEM and SEM analyses.
EFFECTS OF INTERFACIAL ADHESION ON DEFORMATION AND FRACTURE BEHAVIOUR OF COMPOSITES BASED ON POLYPROPYLENE AND GLASS BEADS
Authors: Dung Nguyen Viet
Published: April 2018

In this study, the isotactic polypropylene, a semicrystalline polymer, was used as a matrix for composites containing 20% and 40% (by weight) of glass bead filler. Selected surface treatment was applied to obtain different adhesion between particles and polymer matrix. In addition to non-treated filler, filler treated with i) a release agent (labelled as NO adhesion) and ii) an adhesion promoter (labelled as GOOD adhesion) were incorporated into the matrix. The morphology, tensile mechanical and fracture behaviour (J-integral) were investigated. Morphology observation revealed a poor interfacial adhesion in the case of non-treated and “NO adhesion” samples represented with debonding of particles. In contrast, strong particle-matrix interactions were confirmed in “GOOD adhesion” samples. The presence of rigid filler particles increased the stiffness, while strain at break was decreased with the lowest value for the composites with strong interfacial adhesion. On the other hand, the higher rigidity and lower deformability decreased in fracture toughness.
THE EFFECTS OF HYDROSTATIC PRESSURE ON MBH4 (M = K, Na) STRUCTURES
Authors: Manh Do Phu
Published: April 2018

In recent decades, a lot of efforts has been spent on investigation of metal borohydrides, which can potentially serve as advanced hydrogen storage materials for mobile applications. In this research, we investigate the structure changes under high pressure of the compounds MBH4 (M = K, Na) as important borohydrides in hydrogen technologies, using ABINIT simulation package based on density functional theory (DFT) and the generalized gradient approximation (GGA). The pressure is in a wide range of 0 GPa to 40 GPa. Structural analysis indicates the phase transformation in the examined range of pressure, which is evidenced by the interaction between metal cations and BH4-, interactive behavior of BH4 tetrahedron in the simulated cells, change of volume, distance between B and H ions, and enthalpy difference.
HUMAN HEALTH HAZARD OF POLYCYCLIC AROMATIC HYDROCARBON IN ROAD DUST IN HA NOI METROPOLIS
Authors: Le Ha Vo Thi
Published: April 2018

This study investigates PAHs content in road dust of Hanoi metropolis, Vietnam. The samples were colected from the roads around city and analyzed by gas chromatography mass spectrometry (GC/MS). The total PAHs mass concentration ranges from 33.88 μg/kg to 5588,16 μg/kg, with the mean of 356,24 μg/kg in which HMW accounted up 70 % and LMW made up 30 %. The toxic equivalence factors (TEFs), mutagenic potency equivalent factors (MEFs) and the incremental lifetime cancer risk (ILCR) methodologies were applied to evaluate human exposure to carcinogenic PAHs sources. Carcinogenic equivalents (BaP-TEQ) and mutagenic equivalents (BaP-MEQ) were calculated from the potency relative to BaP (TEF) and BaP (MEF). The value of BaP-TEQ for 8 PAHs varied from 1.13 μg/kg to 195.23 μg/kg with mean of 24.34 μg/kg, while the value of BaP-MEQ ranged 1.45 μg/kg to 123.15 μg/kg with mean of 19.96 μg/kg. Basing on ILCRs model, the total cancer risk for children and adults was up to 1.6×10-5 and 3.9×10-5, posing a moderate potential cancer risk, respectively.
IMPACT ASSESSMENT OF THE EXTENDED PRODUCTION RESPONSIBILITY IMPLEMENTATION IN VIETNAM: A STUDY ON ELECTRONIC WASTE MANAGEMENT
Authors: Nguyen Duc Quang
Published: April 2018

The electronic waste is now raised in Vietnam as emerging issue, not only by its impact on the environment and public health, but also the chance to utilize the natural resources. In order to sustainable management of major urban-mine sources, including e-waste, an Extended Producer Responsibility (EPR) system is proposed under the Decision 16/QĐ-TTg dated 22, May, 2015, to extend the responsibility of producers to the end-of-life product. In this study, the Material Flow Analysis and Policy assessment tool are applied to assess the impact of the EPR system, in case of large home appliances and to find the obstacles on the implementation of the system. Among the experimental appliances, air conditioner has the highest rate of valuable materials and also the highest rate of recyclable materials, then follows the refrigerator, washing machine and desktop computer. On the opposite, Cathode Ray Tube (CRT) monitor has the highest rate of hazardous compounds, where washing machine has no hazardous matter. Three scenarios were developed and assessed based on the obtained benefit–cost from dismantled material and hazardous waste. It is shown that the role of intermediate stakeholders, the infrastructure for e-waste treatment and monetary distribution flows under the pressure of legislation are the main factors that caused failure in the application of the EPR system in Vietnam.
A SURVEY OF VASCULAR PLANT SPECIES IN THE DRY SEASON, CAM MOUNTAIN, AN GIANG PROVINCE
Authors: Hai Ly Nguyen Thi
Published: April 2018

The survey which was conducted in the dry season (from February to April) in Cam Mountain, reported 49 plant species belonged to 45 genera and 29 families. These species include 10 big wood species (G) (20.4 %), 14 small wood species (g) (28.6 %), 7 bush species (17.2 %), 9 creeper species (18.4 %) and 9 herbaceous species (18.4 %). There are 33 species used for herbal medicines, 12 species for wood fire, 11 species for fruit, 10 species for household tools and 9 species for food. Pterocarpus macrocapus Kurz is the species that listed in Viet Nam Red Data Book (2007). The average value of Margalef (d) and Pielou (J’) indexes are 2.45 ± 0.37 and 0.94 ± 0.02, respectively. There are 54.5 % quadrates which (d) and (J’) indexes are higher than Margalef (d) and Pielou (J’) indexes. The Shannon – Weiner (H’) index of 63.6 % quadrats is higher than the average value of Shannon - Weiner index (1.94 ± 0.19). The number of species at quadrats O1T1, O3T1 and O1T2 are more diverse than other quadrats. The transect 1 (T1) to the east is more diverse than the transect 2 to the west of Cam forest.
ACUTE TOXICITY OF BISPHENOL A INDUCED PHENOTYPIC CHANGES ON ZEBRAFISH (DANIO RERIO) DURING EARLY DEVELOPMENT
Authors: Mai Ngo Thi
Published: April 2018

Bisphenol A (BPA) has been considered as a weak environmental estrogen, as similar to estradiol that has a potential in stimulating some cellular responses and phenotype changes. In addition, the ecological impacts of BPA to aquatic organisms have been increasingly raised at environmental relevant concentrations that potentially may affect to human health at early–life. This study used 3-day old zebrafish larvae (Danio rerio) as a model for toxicological testing. The semistatic testing was conducted to investigate the effects of different BPA concentrations (5 mg/L, 6 mg/L, 7 mg/L, 8 mg/L and 9 mg/L) that induced morphorlogical and physiological changes during the early development. As the results, the LC50-24hrs, LC50-48hrs, LC50-72hrs and LC50-96hrs were determined as 9.503 mg/L, 8.688 mg/L, 7.328 mg/L and 6.669 mg/L, respectively. Phenotypic analysis revealed that toxicity caused cardiac edema. The result obtained from this research provided relevant information for environmental and human risk assessments.
A TWO-YEAR FIELD STUDY OF PHYTO REMEDIATION USING SOLANUM NIGRUM L. IN DONGNAI, VIETNAM
Authors: Hung Nguyen Thanh
Published: April 2018

A two- year in-situ phytoremediation trial was conducted in Dongnai province. The phytoremediation efficiency of Solanum nigurm L. was detected, by monitoring the change of soil Cadmium level in the 0 - 20 cm soil depth. The results indicate that soil Cd decreased significantly by planting S. nigrum. The Cd concentrations decreased averagely from 2.75 mg kg-1 to 2.45 mg kg-1 in the first year and 2.33 mg kg-1 to 1.53 mg kg-1 in the second year, separately. Decrease by a factor of 10.6 % in first year and 12 % second year. After two years phytoremediation by S. nigrum, Cd concentrations of the seven experimental plots with S. nigrum growth decreased from 2.75 mg kg-1 to 1.53 mg kg-1, and decrease by a factor of 24.9%. Therefore, using S. nigrum for phytoremediation of Cd contaminated farmland soils seems very promising, and we can conclude that S. nigrum will get a better performance in the warmer area, as the temperature of the experimental area is relatively lower.
WATER USE EFFICIENCY OF RICE-BASED UPLAND CROP PRODUCTION SYSTEMS IN FLOOD-AFFECTED CHAU PHU DISTRICT, AN GIANG PROVINCE, VIET NAM
Authors: Tuyen Nguyen Van
Published: April 2018

Retaining abundant flood water and later using it as crop irrigation water is an issue for the flood-prone area in the Mekong Delta of Viet Nam. The present study aimed to determine an appropriate rice-based upland crop production practice with high water use efficiency and hence the feasibility of retaining flood water for agricultural use in the flood area in the Mekong Delta. On-farm studies were carried out in Chau Phu district of An Giang province from January 2012 to July 2015. Chilli, maize, rice were used as the proxy crops. Crop irrigation water quantity was monitored, and crop yields and economic inputs and outputs were recorded. Results showed that maize or chilli grown on the paddy field were more water-efficient than rice cropping grown alone. Double maize and chilli cropping and rotational rice and maize or chilli cropping required an irrigation water volume of 3,341 m3/ha and 3,686 m3/ha, respectively, compared to 4,289 m3/ha for the commonly-applied double rice cropping. For financial water use efficiency, each cubic meter of water used for crop irrigation yielded a net value of output of 10,950 $VN with double maize and chilli cropping , 6,370 $VN with rotational rice and maize or chilli and 2,790 $VN with double rice cropping practice. These results need to be validated with more farmers’ fields to evaluate the feasibility of the promising crop production systems in larger scale.
EVALUATION OF LAND RESOURCES FOR HAU GIANG PROVINCE’S LAND USE PLANNING ADJUSTMENT
Authors: Quang Nguyen Thanh
Published: April 2018

Hau Giang is one of 13 provinces in the Mekong Delta. Total land area is 162,171 ha (statistics 2014), agricultural land is 141,217 ha accounting for 87.08 % of natural area. To exploit the reasonable land and provide a scientific basis for adjusting the land use planning to 2020, the evaluation of land resources in Hau Giang was carried out. To apply the land evaluation methodology of FAO to research on natural conditions, socio-economic related to land use to evaluate land resources as well as to apply for geographic information system (GIS) and automatically land evaluation system (ALES) gave results positively, quickly and efficiently. Evaluation results showed that Hau Giang had four major land groups with 11 land mapping units; alluvium land group accounted for 37.26 % of natural area. From the map overlay has been integrated 28 land units. Basing on 44 LUTs surveys was selected for 16 LUTs to have development prospects to evaluate land suitability. Land use was divided into 5 main groups: alluvial land belonged to riverside Hau, slightly saline land was not submerged and was shallow, and low-lying saline land was flooded and saline land was salty. To combine with evaluating the current state of land use, productive techniques and socio-economic development needed supplementing of land use planning by 2020 as follows: (1) agricultural land is 141,217 ha (87.08 %); (2) non-agricultural land is 20,918 ha (12.90 %) and (3) unused land is 36 ha             (0.02 %) of natural area.
EFFECTS OF CLIMATE VARIATIONS ON HAND-FOOT-MOUTH DISEASE IN HO CHI MINH CITY
Authors: Thanh Tran Cong
Published: April 2018

Abnormal emergence of epidemics has been believed to be one of the most significant effects of climate change on human health, especially in the tropical zone. Hand-foot-mouth disease (HFMD) which possibly related to climatic changes has emerged in Vietnam since 2003. Ho Chi Minh City (HCMC) is particularly a Southern city with the highest cases and mortality numbers of HFMD in the whole country. Therefore, we conducted a retrospective observational study to analyse the association between climate variations and HFMD in HCMC. HFMD and meteorological data from 2010 to 2014 were collected from The Preventive Medicine Centre of HCMC and Sub-Institute of Hydrometeorology and Environment of South Vietnam. The research used time-series analysis and Poisson regression model to analyse the effects of climate fluctuations on HFMD, adjusting for seasonal and trend effects, lag effects and degrees of freedom. The research findings showed that climate variables (average temperature, average humidity, minimum humidity, precipitation, and the Southern Oscillation Index (SOI) daily data) had a significant influence on HFMD. Noticeably, the effects of climate variations on HFMD were considerable in children aged 1-3 and 3-5 years. The maximum lag effects were 3 weeks for temperature and humidity, 4 weeks for precipitation, and 6 weeks for SOI. Specifically, the relative risk of HFMD increased by 7.2 % for every 1°C increase in temperature, 6.75 % for every 1 % increase in humidity, 6.32 % for every 5 mm increase in precipitation, 4.42 % for every 5 units increase in SOI. The study provided a quantitative evidence that the increase of HFMD was significantly affected by the increase of climate variations. Therefore, the study provided the foundation for developing theory that is used in models and, ultimately, for making forecasts about future impacts of HFMD associated with climatic changes.
REMOVALS OF CHAIN-LIKE AND PIN-LIKE ALGAE BY POSITIVELY CHARGED BUBBLE FLOTATION
Authors: Thuy Bui Thi
Published: April 2018

The objective of this study was to investigate the effects of positive ferric-bubble on behaviors of chain-like and pin-like algae (i.e. Phormidium specie (sp.) and Nitzchia pungens, respectively). Two selected algae were cultured in a laboratory under the certain conditions. At stationary phase, algae were below 4 μm in diameter and in the range of 50 ~ 100 μm for chain-like algae, of 20 – 35 μm for pin-like shape in length; with negatively charged at cultivated conditions (pH from 6.5 to 9). Positive ferric-bubbles were generated by adding coagulants (as Fe3+) and were injected at a pressure of 5 bars with a bubble rate of 30 % into a 10 L-acryl made reactor with algal-containing tap water. Removal efficiencies were assessed by the cells number, Chlorophyll a reduction and the morphological changes (i.e. cell structure). For cells number, about 90 % of both algae were removed whilst pin-like algae obtained the higher reduction of Chlorophyll a, showing by 92 % in comparison with about 85 % of chain-like shape. The breakup of algal morphologies occurred for chain-like cells only. The structure of filaments affects performance of positively charged bubble flotation.
FORECASTING THE WATER QUALITY AND THE CAPACITY OF RECEIVING WASTEWATER OF THE DONG NAI RIVER UP TO 2020
Authors: Tuan Le Quoc
Published: April 2018

Dong Nai river, the largest river system in the South East region, flows through five provinces in the South East area. Dong Nai river serves water for living, production, irrigation, aquaculture, navigation, and hydropower. It receives a huge impact from the natural and artificial elements, such as municipal wastewater from residential areas and urban centers; industrial wastewater from industrial zones, toxic wastewater from agricultural activities, etc [4, 5, 6]. Therefore, the prediction of water quality change and the capacity of receiving wastewater are very essential in environmental protection for Dong Nai river. The study results showed that the water quality of Dong Nai river is currently achieved to the standard requirement and the using purposes. However, there were some sections where had locally polluted signs and had not be used (such as Dong Nai river in the section 3). Predictably up to 2020, pollutant load will increases, however, the water quality of Dong Nai river is still achieving the fundamental purpose of water supply, except TSS which, water from the area below Tri An damp to Dong Nai bridge, is not reached the regulation permit in the beginning and ending of rainy season. To protect the water of Dong Nai River, the optimal solution is necessary to collect and treat all wastewater from industrial, domestic, livestock and medical activities to get the standard permission before discharged into Dong Nai river. At the same time, considering the capacity of receiving wastewater on the each section of Dong Nai river is conducted to allow new investment projects and license of wastewater dischargement.
PERFORMANCE OF H2O2 - AERATED BIOFILTER IN TREATMENT OF WASTEWATER CONTAINING HUMIC ACID
Authors: Tuan Le Van
Published: April 2018

This work presents the results of adding H2O2 into a modified aerated biofilter (ABF) for treatment of refractory organic constituents in wastewater. The activated sludge, taken from wastewater treatment system of Hue Beer Company, was long-time cultured in laboratory with beef extract-peptone solution. The synthetic wastewater was prepared from solutions of glucose, ammonium acetate, sodium bicarbonate, potassium dihydrogen phosphate, sodium chloride, potassium chloride, calcium chloride and magnesium sulphate. As a refractory organic compound, humic acid (HA) was added into the wastewater; and parameters of chemical oxygen demand (COD) and color were measured to estimate the treatment performance. The experiments were conducted in continuous mode to observe the effects of H2O2 concentration (25–100 mg/L) and hydraulic retention time (HRT: 24–18 hours; according to organic loading rate, OLR: 0.51–0.67 kg-COD/m3/d) on the aerated biofilter system, under identical treatment conditions (COD: 505 ± 10 mg/L, HA concentration: 25 mg/L, pH: 7.0 ± 0.2, temperature: 25 ± 3.0 oC, and air flow rate: 1.0 ± 0.1 L/min). At the concentration of H2O2 50 mg/L and HRT of 24 hours, the ABF reactor yielded highyielded highyielded high yielded high yielded highyielded highyielded highyielded highyielded highest treatment est treatmentest treatmentest treatmentest treatmentest treatment est treatmentest treatmentest treatment efficienc efficiencefficiencefficiencefficiencefficienc efficiency (95(95 % COD and COD and COD and COD and COD and COD and COD and 74 % color colorcolorcolor). Consequently, H2O2 could be used to improve the effectiveness of activated sludge process in treatment of wastewater containing refractory organic compounds.
MODIFICATION OF TITANIUM DIOXIDE NANOMATERIALS BY SULFUR FOR PHOTOCATALYTIC DEGRADATION OF METHYLENE BLUE EVEN UNDER VISIBLE LIGHT
Authors: Lam Nguyen Tan
Published: April 2018

This paper presents a study on preparation of sulfur doped titanium dioxide using potassium fluorotitanate and sodium sulfate as precursors. The obtained results indicated that the doped TiO2 exhibited very high photocatalytic activity for degradation of methylene blue even under visible light. The increasing in the added sulfur amounts led to significantly increase in the degradation of methylene blue. When the S/TiO2 mole ratios increased from 10 to 25%, the degradation of methylene blue under compact light increased from 30.87% to 67.06%, respectively.
ASSESSMENT OF FARMERS’ PRONE STATE TO NATURAL DISASTERS: A CASE OF MAINSTREAM HYDROPOWER DEVELOPMENT IN THE LOWER MEKONG DELTA, VIETNAM
Authors: Anh Hoang Ha
Published: April 2018

The study provides a comprehensive view at the prone state of the Mekong Delta under baseline conditions of hydropower development. Communities in Vietnam Mekong Delta have main income sources from rice farming, fishing and aquaculture, so changes in floods pattern or salinity can directly affect people’s livelihoods. Among 13 provinces in Mekong River Delta, there are 9 provinces that have moderate Potential Impact Sub-Index (PII). Tra Vinh has the PII since its population is affected by both floods and salinity more heavily than other provinces. The provinces that have higher PII also have higher Social Vulnerability Index (SVI) to impacts. All provinces except Long An have moderate vulnerability to impacts because Long An not only has low PII but also high Adaptive Capacity Sub-Index (ACI) which makes it less vulnerable. Tra Vinh has highest SVI because of its exposed state to floods and salinity and high poverty rate. The results show that majority of Mekong River Delta are vulnerable to floods and salinity.
ASSESSMENT OF URBAN ENVIRONMENTAL SUSTAINABILITY IN HUE CITY AS A CASE STUDY
Authors: Tuan Tran Anh
Published: April 2018

Hue city was chosen for a pilot application of indicators on environmentally sustainable city, which were developed by Vietnam Ministry of Natural Resources and Environment. The indicator set is composed of four key categories (water, air, solid waste and climate change response), which are broken down into 16 underlying performance indicators. In reality, there has not been any assessment process in place to guide cities in Vietnam in doing their own assessment. In this research, an assessment process including 5 steps was built up; and a barometer with 5 classification bands ranging from 0 to 100 was recommended to use for both category and overall assessment. The weighting of 4 urban environmental categories was undertaken based upon a Delphi method with informed inputs from an expert panel. The 5 - step analysis process showed that Hue city was ranked “medium” with the score between 41 - 60 for water and solid waste, “fairly good” in terms of air (score of 85) and “poor” as to climate change response (score of 40). The sum of all category scores of Hue city, which is also rebased to 100, is valued at 60. Thus, the city was ranked “fairly good” in the overall. Such assessment results are much expected to provide assistance in decision-making at various levels of local authority and help them set forth some appropriate improvement measures on urban environmental sustainability issues. As such, the city would soon meet some concerned requirements to become a leading city of Vietnam in urban environmental sustainability.
SORPTION STUDIES OF CRUDE OIL ON ACETYLATED SAWDUST
Authors: Duc Nguyen Trung
Published: April 2018

Acetylated sawdust (AS) has been studied as sorbent for crude oil spill clean-up operations in the aqueous environment. Sorption kinetics and isotherm studies were carried out under various experimental conditions. The experimental data were particularly tested using the Langmuir isotherm model and the Freundlich isotherm model. The results showed that the acetylation of sawdust enhanced the equilibrium sorption capacity of biomass towards the crude oil. Kinetic studies have shown that the data better fitted the Langmuir moldel than the Freundlich model. The maximum adsorption capacity of AS was 7.9 g/g of crude oil. These values indicated that the acetylated sawdust is a suitable sorbent with potential for further development for oil spill treatment.
INITIAL ASSESSMENT OF SOME RELATED SOCIO-ECONOMIC PARAMETERS UNDER THE IMPACTS OF CLIMATE CHANGE AT DISTRICT 8 IN HO CHI MINH CITY
Authors: Bao Nguyen Phu
Published: April 2018

About 7.9 % of population is living in poverty at District 8, which is one of the most vulnerable areas to climate change in Ho Chi Minh City (HCMC). The impacts of climate change (CC) on some related socio-economic parameters at District 8 were assessed using analytic hierarchy process (AHP) and livelihood vulnerability index (LVI). For this, four Asian Development Bank’s criteria including public health, transport, energy, and water supply and drainage (WSD) were used. In addition, however, six World Bank’s criteria including land use, population, gross domestic product (GDP), urban expansion, agriculture and wetland were also used just for initially trying whether or to what extent they can be useful for such downscaled application. Results of this study show that the level of CC impacts on the residential areas is rather high, with an average LVI of 0.056. In addition, the results of AHP shown that the impact levels on the study fields are determined to follow a decreasing order as: first level group including energy, water supply and drainage, transport, and public health (with total score 0.22); the second level group including land use and wetland (with total score 0.14); the third level group including population and urban expansion (with total score 0.1); and at last the fourth level group including GDP and agriculture (with total score 0.09).
INVESTIGATION OF ABILITY LIBERATION OF METALS FROM PRINTED CIRCUIT BOARDS BY MECHANICAL PROCESSES FOR PHYSICAL SEPARATION PROCESSES
Authors: Hung Ha Vinh
Published: April 2018

Physical separation process was widely applied for the separation of metallic component from Printed Circuit Boards (PCBs) due to their advantages as friendly-environment, facilitated control, and low-cost. However, the efficiency of physical separation depends on a level of the liberation between the metallic and non-metallic components which is conducted by mechanical processing.In this study, the liberation of metals from computer PCBs was conducted in detail by mechanical processes including cutting and crushing. The obtained results demonstrate the distribution metallic and non-metallic component weighs as a function of particle sizes. The separation efficiency of metals was conducted by air separation using vacuum sorter equipment. The results showed that the comminution processes using hammer mill for reach the highest efficiency with 92 % recovery and 87 % grade of metallic components in the heavy fraction with particle size 1.0 - 1.4 mm by air separation process.
IMPACTS OF CLIMATE CHANGE AND SEA LEVEL RISE ON SALINITY INTRUSION IN THE LOWER DONG NAI RIVER SYSTEM
Authors: Thu Ha Nguyen Thi
Published: April 2018

Ho Chi Minh City (HCMC) is ranked among the top 10 cities in the world most likely to be severely affected by climate change and sea level rise (SLR). This study was to assess the impacts of change of upstream flow and sea level rise due to climate change on salinity intrusion in HCMC. The MIKE 11 model with modules hydrodynamic (HD) and advection-dispersion (AD) was applied to this problem by setting up the whole lower Dong Nai river system. Based upon the observed water level and salinity concentration data in 2009, the calibration and validation results indicated that the MIKE11 model was able to simulate the streamflow and salinity concentration with NSE values exceeding 0.6 for both calibration and validation periods. As a result, the differences in salinity concentration under climate change and SLR scenarios were analyzed. The simulated results illustrate that the saltwater will move inland in the future, especially in the dry season.
APPLICATION OF PRINCIPLE COMPONENT ANALYSIS TO BUILD PROVINCIAL ECO-EFFICIENCY INDEX FOR BINH DUONG PROVINCE FROM 2001-2012
Authors: Nhu Tam Doan Ngoc
Published: April 2018

Based on a proposed concept of Regional Eco-Efficiency of Zhou Zhenfeng, a set of indicators for assessing, eco-efficiency of provincial level has been conducted. Set of indicators included 26 indicators, and was divided into 3 groups: Socio-Economic Development Index (SDI) (9 indicators); Resources Consumption Index (RCI) (7 indicators) and Environmental Pressure index (EPrI) (10 indicators). Principle component analysis (PCA) was used to assess Eco-efficiency Synthetic Index (ESI) of Binh Duong province in the 2001-2012. Results shown that the ESI of Binh Duong province has been clearly improving from 2001-2012. RCI and EPrI respectively had a significant correlation with SDI. Results also have been shown that the industrialization generated waste and if the pollution control solution is not effectively so environmental pressure is continuously increase and degrade the environment.
SIMULTANEOUS REMOVAL OF SOME HEAVY METALS AND ARSENIC FROM AQUEOUS SOLUTIONS BY Phragmites australis
Authors: Huyen Nga Tran Thi
Published: April 2018

In this study, Phragmites australis (common reed) was transplanted into solutions added with different concentrations of Mn, Zn, Cd, Pb, and As for 30 days in the laboratory (10 days of incubation and repeated three times without changing the plant) to assess the removal of these metals and its accumulation in the plant. The results showed that high removal efficiency was achieved by growing P.australis. The highest daily removal rates of heavy metals and As were obtained after 1 day of new solution addition. The highest concentrations of Mn, Zn, Cd, Pb, and As in the plant roots were 3920, 1020, 90.9, 1350, and 183 mg kg–1 dry wt., respectively; those in the stems were 465, 108, 26.4, 227, and 74.0 mg kg–1 dry wt.; and those in the leaves were 716, 150, 18.1, 157, and 88.3 mg kg–1 dry wt. The results of this study indicated that P. australis has the ability to remove simultaneously these metals from water, making it a potential species for phytoremediation of wastewater from Pb-Zn mine.
STUDIES ON DISTRIBUTION AND FRACTIONATION OF HEAVY METALS IN SEDIMENT OF CAU RIVER, VIETNAM
Authors: Anh Van Dieu
Published: April 2018

Cau River, one of the major rivers of Thai Binh River Systems, has been under pressure from discharge from the economic and social development activities of the region. Water and sediment samples will be collected along Cau River to determine the spatial variability of metal in Cau River. Sediments collected from Cau River were extracted sequentially to investigate the distribution and fractionation of metal in Cau River. Results showed that the presence of certain metals in water and sediment with the concentrations ranged in a wide variation. In water Cu (58-181 μg/L), Pb (0.6-1.85 μg/L), Zn (18.1-32.5 μg/L), Cd (0-0.02 μg/L), Ni (3.04-4.41 μg/L), Cr (2.72-5.07 μg/L); in sediment Cu (27.6-401 mg/kg), Pb (0-282 mg/kg), Zn (3.9-71.9 mg/kg), Cd (0.01-2.44 mg/kg), Ni (2.24-5.89 mg/kg), Cr (4.08-11.5 mg/kg). Sequential extraction for study the distribution of metal species in sediment showed that metal mainly concentrated immobile form of residues fraction, organic compound bound fraction and Fe-Mn oxide associated fraction. This dominant existence of metal result in the tendency of metal assimilation in sediment and low bioavailability. However, some toxic metals such as Cd, Cr found moderated soluble form must be studied more for their release to water phase and and bioaccumulation.
RESEARCHING GANODERMA RESIDUES APPLYING IN EARTHWORM CULTIVATION PROCESS (PERIONYX EXCAVATUS)
Authors: Ngoc Nhi Nguyen Thi
Published: April 2018

The research of applying Ganoderma residue in earthworm Perionyx excavatus cultivation have promised in reducing environmental pollutions from mushroom farm and brought high economic efficiency. A 9 m square with 9 experimental formulas were applied to investigate the effect of Ganoderma residue to earthworm growth. The results showed that Perionyx excavatus increased mass in all formulas added cultivated Ganoderma residues, in which the largest increased in formula of 75 % cultivated Ganoderma residues treated with Trichoderma, from 0.59 kg/m2 initial to 2.62 kg/m2. In addition, Perionyx excavatus growth and development completely was seen on the medium with 100 % cultivated ganoderma residues, reached 1.89 kg/m2. Although the growth rate of the Perionyx excavatus cultivated with Ganoderma residues was slower as compared to farming entirely by cow manure (2.94 kg/m2), in the long run, this process will bring farmers higher profits (56.500 VN dongs /m2 of culturing). This cultivation process might be promising to be applied in regions with mushrooms farms for economic and environmental reasons.
ADSORPTIVE REMOVAL OF FIVE HEAVY METALS FROM WATER USING BLAST FURNACE SLAG AND FLY ASH
Authors: Chung Nguyen Thuy
Published: April 2018

Heavy metals can be serious pollutants of natural water bodies causing health risks to humans and aquatic organisms. A study was conducted to remove five heavy metals from water by adsorption onto an iron blast furnace slag and a fly ash in batch experiments. Increase of pH increased adsorption of all metals. Equilibrium adsorption of all metals was successfully modelled using Langmuir, Freundlich and Dubinin-Radushkevich models, with Freundlich model fitting the data the best. Langmuir adsorption maximum at pH 6.5 for fly ash ranged 3.4 - 5.1 mg/g with the adsorption capacity for the metals in the order, Pb > Cu > Cd, Zn, Cr. The corresponding values for furnace slag were 4.3 - 5.2 mg/g, and the order of adsorption capacities, Pb, Cu, Cd > Cr > Zn. The kinetics of adsorption fitted well to both the pseudo-first order and pseudo-second order models, but the fit was slightly better for the pseudo-second order model.
DETERMINATION OF ARSENIC CONTENT IN WASTEWATER-FED FISH POND IN HOANG MAI DISTRICT, HANOI, VIETNAM
Authors: Ha Le Thai
Published: April 2018

Aquaculture in pond fed with wastewater has been practiced since the 1960s in Hoang Mai and Thanh Tri districts in Hanoi, Vietnam. Wastewater after directly discharged in to Kim Nguu and To Lich river is currently used for cultivation of vegetables and fishes. According to the previous studies, the content of some heavy metals in water and sediments from Kim Nguu and To Lich river exceeded the Vietnamese standard values. In this study, arsenic concentration in water, sediment, fish and plant collected from a wastewater fed-fish pond in Hoang Mai district, Ha Noi, Vietnam were determined by graphite furnace atomic absorption spectrometry (GF/AAS). Arsenic concentration in water collected from inlet and outlet sites of the pond were of 45.86 and 23.22 μg/L, respectively and those levels were higher than the Vietnamese standard. About 14% of arsenic entered the fish pond was in the suspended particulate mater (SPM) form. Arsenic concentration in the sediment ranged from 12.26 to 23.87 mg/kg (dry weight). The highest levels of arsenic found in the sediment near the pond outlet were probably caused by the movement of the sediment and heavy metals with the water flow. Based on the Vietnamese standards for agriculture soils, the studied pond sediment is not safe for crop application. Arsenic contents of 0.20 and 0.06 mg/kg (dry weight) were found in tissues of common carp and tilapia. The lower As contents in the outlet water in comparison to the inlet water showed that part of As was removed in the fish pond by different processes including the sedimentation and bio-adsorption. The As contents in the coarse stems/leaves of the water spinach samples were about 2.6 times higher than those in the shoot tips/younger leaves. As the findings, the water spinach and fish in this wastewater –fed fish pond were considered safe for human consumption with respect to arsenic content and Vietnamese standard.