Cover & Content
Pig production and risk exposure: A case study in Hung Yen, Vietnam
Abstract | PDF
Abstract: The effects of direct and indirect input factors on pig productivity and its production risk in Hung Yen, Vietnam, were investigated. In using a moment-based approach, a Cobb-Douglas production function was applied to capturing mean, variance, and skewness effects. The results of this study showed that the expenditure for feed and time length of production reduced both the variation in productivity and downside risk, whereas an expanding production scale increased both the variation in productivity and downside risk.
Screening of aromatic rice lines by using molecular marker and sensory test
Abstract | PDF
Aromatic rice has become popular owing to its aroma. Growing demand for aromatic rice has spurred interest of breeders. In this study, twenty five BC1F1 rice lines of backcross hybrid combinations were used to evaluate aromatic characteristics through sensory test and using microsatellite markers. There are twelve lines had aroma and one no aroma were chosen though sensory test. Allele Specific Amplification with four primers (External Antisense Primer, External Sense Primer, Internal Non-fragrant Sense Primer, and Internal Fragrant Antisense Primer) were used for identifying fgr gene locus in 25 rice lines. Analysis of PCR results showed that BC1F1 population segregated into 1:1 ratio (homozygous fragrant: heterozygous non-fragrant). Thus, twelve promising lines were identified with homozygous fragrant genotype.
Effects of extraction methods and storage conditions on histamine content in frozen tuna (Thunnus albacares)
Abstract | PDF
This study was undertaken to assess different extraction methods and the effects of times and temperatures on histamine produced in storage frozen tuna. The results showed that histamine in tuna samples could be efficiently extracted with perchloric acid 0.6 M and trichloroacetic acid 6%. The effective method for determining histamine concentration was benzoylation procedure. Tuna stored at 4oC resulted in higher histamine level (42.24 mg/kg) than tuna stored at 0oC (161.29 mg/kg) after 7 days of storage. Also, bacteria increased from 4.54 log10 cfu/g to 5.88 log10 cfu/g in the samples stored at 0°C, while for the samples stored at 4°C, an increase was shown dramatically in counts from 4.54 log10 cfu/g to 8.88 log10 cfu/g. These findings revealed that there was high correlation between storage conditions and histamine formation.
A framework for transferring algorithms designed on matlab/simulink to arm microcontroller embedded systems
Abstract | PDF
Recently, demand of implementation stand-alone embedded systems has increased sharply. This article represents a method for building a framework that can implement control algorithms designed on Matlab/Simulink to embedded sysems. An inverted pendulum stabilizing controller, running on a STMicroelectronics low-cost STM32F4 Discovery development kit, is used as a demonstration. The control algorithm, after designed and simulated on Matlab/Simulink, is configured to generate the corresponding embedded C code by using Matlab Realtime Embedded Coder. This code is combined with microcontroller peripheral libraries to make a complete Keil C project. In this project, the C language main function is generated automatically by using TLC – Target Language Compiler; however, users must write additional code to complete the whole coding. Experimental results of the demonstrative algorithm show that by using the proposed framework the control algorithm only has 0.001 ms of sample time error. Response quality of the inverted pendulum is as good as simulation results in term of fast response, low overshot and steady error.
A simulation study for optimizing staff numbers of security check-point at the airport terminal
Abstract | PDF
The security check-point area of airport terminals is one of the busiest places at airports at certain periods. The passengers are waited for queues and time delays during the check-point process. In fact, when passengers have to spend much time in that area, they will feel unsatisfied. These problems are due to constraints in the capacity of service facilities such as equipments, staff planning. This study presents a simulation model, which will help the airport operations managers develop an efficient planning for optimizing staff numbers required at terminal security areas with changes in passenger volumes depending on time of day on the week. The model is developed from SIMIO software with high flexibility through making the different experiments to achieve regularly basic conditions of the airport. Results from this study showed that the model will provide invaluable in-sight in operating of terminals to achieve minimum cost and improve the waiting time as well as higher customer satisfaction.This work will start the research on model driven development of airport simulation model.
Determination of the confining effect of geogrid rein-forcement from large scale triaxial tests
Abstract | PDF
The immense contribution of geogrids to the strength of reinforced soil is well known in science and nowadays also increasingly accepted in the industry. Reinforced granular material is a composite material which combines properties resistance of two different materials in such a way to increase its bearing capacity. However, the differences between calculated and measured deformations of geogrid-reinforced structures indicate that the exact behaviour of geogrids in soil is not totally understood yet. To allow for better assessment of the composite behavior, a series of large-scale triaxial tests were conducted on unreinforced and reinforced gravel specimens of 50 cm in height and 23 cm times 23 cm in cross-section, using an apparatus developed at the Institute of Industrial Science, University of Tokyo (Anh Dan et al. 2006). In addition to the variation of the cell pressure, the test series also includes the variation of geogrid types. Results of unreinforced and reinforced test series showed a significant increase of the peak strength as well as a reduction of the deformations of the tested samples due to the reinforcement. A confining effect of the reinforcement was clearly identified and could be explained with a mechanical model. A calculation method, which is based on the mechanical model, was used to draw the stress paths for a series of reinforced tests.
Synthesis of silver nanocubes and application in SERS
Abstract | PDF
This work describes the rapid route to monodispersed silver nanocubes. By adding a trace amount of sodium borohydride and clorohydride acid to the conventional polyon synthesis, the reaction time was significantly shortened from 16-26 h to 4-5 h, increasing both the rate of production and uniformly the shape of monodispersed nanocubes of 40; 60 and 70 nm in size. The synthesized Ag nanocubes have been characterized by UV–vis, TEM, and XRD. Our results show that the SERS technique is able to detect Rd3B within wide concentration range, i.e. 10-14 – 10-8 M, with lower limit of detection (LOD) being 10-14 M. It demonstrates that the Ag nanocubes have potential applications in SERS for the detection of biomolecules and biomarkers (or dye molecules) to early detection and diagnosis of cancers or serious diseases.
Biodiesel synthesis from algae (Chlorella sp.) in condition of subcritical methanol
Abstract | PDF
In this study, transesterfication reaction under subcritical condition of methanol (or called subcritical methanol method) was employed to directly produce biodiesel from chlorella sp. instead of conventional method that based on acid/base catalysts. The effect of reaction parameters on FAME (biodiesel) conversion such as temperature (165 -185 °C), methanol to biomass ratio (10/1-25/1, g/g), water content (5 – 80%), and reaction time (1-12 h) was studied. According to the experimental results, FAME conversion increased with the increase of reaction time and highest FAME conversion 95% at 175 °C, 20/1 (g/g) methanol to biomass ratio and 50% water content in biomass.
The effect of crop rotation on the structure of the fungal community colonising rice straw residues in paddy rice cultured soil in the Mekong Delta of Vietnam
Abstract | PDF
In this study, we compared a rice monoculture and alternating crop rotation on fungal population . The studied crop rotation systems were rice-rice-rice (CRS1), rice-rice-baby corn (CRS2), rice-rice-mungbean (CRS3) and baby corn-rice-mungbean (CRS4). A fungal primer pair (ITS1–ITS2) was used to amplify internal transcribed spacer (ITS) sequences from total DNA extracts from rice straw residues. Amplified DNA was analyzed by DGGE. Individual bands from DGGE gels were cloned and sequenced. DGGE gels representing the fungal communities of the continuous rice and the rotation site were compared and related to fungal identified from the field.The results demonstrate that the colonizing rice straw residues fungal communities were affected differently depending on crop rotation. Significant differences between the fungal communities from rice straw residues of rice in monoculture and alternating crop rotation of mungbean and baby corn were found. Cloning and sequencing of bands from the DGGE gels revealed the presence of Ascomycota and Basidiomycota that are common in agricultural soils. It was shown that the colonizing rice straw residues of crop rotation seemed to select the phylum Ascomycetes, while different members of the phylum Ascomycota and Basidiomycota were detected in the of colonizing rice straw residues rice monoculture.
Sorption of Pb(ii), Cu(ii) and Cd(ii) by biomass of the different activated sludge
Abstract | PDF
AbstractBiomass of digested sludge and resting sludge can be easily applied as a cheap bio-adsorbent for heavy metal ions such as Pb2+, Cu2+ and Cd2+. Langmuir model was found to fit the experimental adsorption and desorption data of the heavy metal on to the biomass of sludge. That has the competition uptake between the difference metal with another when the adsorption system has the di-metal, and tri-metal combination. The maximal adsorption capacity of resting sludge was 0.517 mM Pb2+/g; 0.552 mM Cu2+/g; 0.389 mM Cd2+/g, and the maximal adsorption capacity of the digested sludge was 0.478 mM Pb2+/g, 0.43 mM Cu2+/g and 0.549 mM Cd2+/g. In the absorption system, it was found that, di-metal combine such as (Cu2+ - Cd2+), (Pb2+ Cd2+), and (Cu2+ - Pb2+), the metal uptake Cu2+ ≈ 3Cd2+, Pb2+ > 3Cd2+, and Cu2+ ≈ Pb2+ respectively. When tri-metal Cu2+ - Cd2+ - Pb2+ combines the number of complex formation varies in the following order: Pb2+ > Cu2+ > Cd2+. Extracellular polymeric substances (EPS) were extracted by sonication method. Humic substances were greater than protein and polysaccharide for digested sludge, for resting sludge the protein is greater than humic. The ratio protein/polysaccharide varies from 1.25 to 2.7, this ratio is highest for resting sludge. Affinity absorption of Cu2+ and Pb2+ was higher than Cd2+, that have the competition metal uptake with functional groups such as hydroxyl, carbonyl, amide on the biomass surface of the sludge.Keywords: Activated sludge; Bio-sorption; Cd2+; Cu2+; Pb2+Tom TatHAP THU CAC KIM LOAI NANG Pb(II), Cu(II) va Cd(II) TREN SINH KHOI KHAC NHAU CUA BUN HOAT TINHSinh khoi cua bun hoat tinh va bun duoc xu ly la chat hap thu sinh hoc re tien doi voi cac kim loai nang nhu Pb2+, Cu2+ and Cd2+. Phuong trinh dong hoc Langmuir mo ta qua trinh hap thu va giai hap thu cac kim loai nang doi voi chat hap thu la sinh khoi cua bun rat phu hop. Trong he da nguyen to co su hap thu canh tranh giua cac nguyen to voi nhau. Hap dung cuc dai cua bun hoat tinh tren 1 gram sinh khoi kho tuong ung 0,517 mM Pb2+; 0,552 mM Cu2+; 0,389 mM Cd2+; trong khi do hap dung cuc dai cua bun hoat tinh da duoc xu ly tuong ung 0,478 mM Pb2+, 0,43 mM Cu2+ va 0,549 mM Cd2+. Ket qua nghien cuu cho thay, trong he hap phu co 2 cau tu (Cu2+ - Cd2+), (Pb2+ - Cd2+), va (Cu2+ - Pb2+) thi trat tu canh tranh tuong ung Cu2+ ≈ 3Cd2+, Pb2+ > 3Cd2+, and Cu2+ ≈ Pb2+. Trong khi do doi voi he hap phu co 3 cau tu Cu2+ - Cd2+ - Pb2+ thi trat tu canh tranh la Pb2+ > Cu2+ > Cd2+.Extracellular polymeric substances (EPS) duoc chiet bang phuong phap sieu am. Ket qua nghien cuu cho thay doi voi bun da duoc xu ly hop phan cua humic nhieu hon protein va polysaccharide, nguoc lai doi voi bun hoat tinh co protein cao hon humic. Ty le PN/PS thay doi tu 1,25 den 2,7: ty le nay cao nhat doi bun hoat tinh. Ai luc hap phu Cu2+ va Pb2+ boi bun hoat tinh cao hon Cd2+ la do co su canh tranh hap thu cua cac ion kim loai doi voi cac nhom chuc hydroxyl, carbonyl, amide tren be mat sinh khoi bun hoat tinh.Tu khoa: Bun hoat tinh; Cd2+; Cu2+; Pb2+; sinh hap phu
Cultural approach: A potential pedagogy for promoting learners’ insights into cultural aspects in literary works
Abstract | PDF
This study would attempt to ascertain the truly inseparable relation between culture (Geert Hofstede, 1997), and literature (Nguyen V.D., 2001) and investigate a potential pedagogy to promote learners' insights into cultural aspects found in literary works. It is a descriptive research which comprises a variety of authors' viewpoints about the relation of culture and literature, what the cultural approach or New Historicism (Ann B. Dobie's book, 2001) is, and the analysis of the three selected American stories, namely Harriet Beecher Stowe's Uncle Tom's Cabin (1853), Kate Chopin's The Awakening (1921) and William Faulkner's A Rose for Emily (1930), based on cultural lens. This study also might encourage the application of a cultural approach as a potential pedagogy (Pham T,Vu L.H & Nguyen N,H, 2001). The research would inspire teachers to conduct further research to test both the effectiveness of this approach in teaching literature and the learners' attitudes towards it as well.
Effect of beta-glucans on hematological, immunoglobulins and stress parameters of striped catfish (Pangasianodon hypophthalmus) fingerling
Abstract | PDF
The study aimed to investigate the effect of beta-glucans on hematological, immunoglobulins and stress parameters of striped catfish. The study included two experiments. In the first experiment, experimental fish (16.2±0.74 g) was fed for 30 days with feed containing different beta-glucans concentrations (0, 0.5, 1.0, 1.5, 2 and 2.5 g/kg). Fish blood were collected after 0, 1, 3, 7, 14 and 30 days of feeding for analysis of hematological parameters, whereas glucose, cortisol concentration and total immunoglobulins (Ig) were analyzed before initiating experiment and after 7, 14 and 30 days of feeding. In the second experiment, experimental fish (18.5±0.65 g) was fed beta-glucans (1.0 g/kg feed) for one, two and three weeks. After beta-glucans feeding with different period, fish was crowded stressing at high density (3000 fish/m3) for four hours then transferred into tanks (500 L) at lower density (60 fish/m3) and blood samples were collected after 24, 48 and 72 hours for analysis of glucose, cortisol concentration and Ig. The result of experiment 1 showed that fish fed 1 g beta-glucan/kg feed had significantly higher red blood cells, white blood cells, hemoglobin, hematocrit and Ig compared to other treatments. Blood glucose and cortisol concentration in treatment fed 1.0 g/kg feed were significantly lower compared to other treatments. In the second experiment, the concentration of glucose and cortisol in fish fed beta-glucans (1g/kg feed) for three weeks were significantly lower compared to fish fed beta-glucans for one and two weeks when fish being stressed at high density. In fish fed beta-glucans for three weeks, total immunoglobulins was significantly higher than those of other treatments. In conclusion, the optimal level of beta-glucans adding into diet of striped catfish fingerlings should be 1.0 g/kg which improved fish health and stress resistance
Chemical composition, antioxidant activity of crude polysaccharide extracted from brown seaweed Sargassum microcystum and its effect on growth performance and survival of whiteleg shrimp Litopenaeus vannamei via dietary administration
Abstract | PDF
The aims of this study were to evaluate antioxidant activity of polysaccharide extracted from S. microcystum and examine its positive effect on growth performance and survial of whiteleg shrimp (Litopenaeus vannamei). Polysaccharides from brown seaweed Sargassum microcystum were extracted by four methods (1) hot-water within 3 h, (2) hot-water within 6 h, (3) 0.1N HCl (100oC) within 3 h, and (4) 0.1N HCl (100oC) within 6 h. The extracts were then analyzed for chemical composition and antioxidant activities. The extract showed the highest antioxidant activity could be used to examine its effectiveness on whiteleg shrimp culture via dietary administration. For trial on shrimp, whiteleg shrimp were reared in a recirculating seawater system with 500-L tanks and fed the pellet diets containing 0.5, 1.0, and 2.0% of hot-water extract. Shrimp were fed the diet without extract supplemented served as control group (0%). After 60 days of feeding, survival rate and growth parameters of shrimp were evaluated. The results showed that protein concentrations of polysaccharide extracts were low and varied from 1.3 to 6.8%. The polysaccharide extracted with hot-water within 6h was higher phlorotannin, glucose and L-fucose concentrations than those in other extracts. However, higher SO42- concentration was found in 0.1N HCl extract within 3 h extract. The significant interactions between solvent and extraction time were observed that affecting yield of polysaccharide and chemical composition as phlorotannin, glucose and SO42- concentrations. Hot-water within 6 h extract showed the highest antioxidant activity indicating by high DPPH● free radical scavenging (IC50 = 0.434 mg mL-1) and ferric reducing power activity (OD0.5 = 2.55 mg mL-1). Whiteleg shrimp that being fed the diets incorporating with hot-water extracts at 1.0% had significantly higher growth performance than those in the control diet. However, there was no significant differences in daily length gain and survival rates among treatments. Therefore, it is concluded that polysaccharide extracted from S. microcystum could be growth promoter in whiteleg shrimp culture.
Physico-chemical properties of fourteen popular cocoa bean varieties in Dongnai – highland Vietnam
Abstract | PDF
Cocoa (Theobroma cacao L.) is a major, crucial economic, global crop and has been maintained several nutritional benefits. The exporting volume of Vietnamese cocoa bean is increasing in the world cocoa trade. The beans of fourteen popular cocoa varieties that are commonly cultivated in Trang Bom (Dong Nai, Vietnam) were characterized for their physico-chemical qualifications on the background of post-fermented cocoa beans and dehydration in the region of Trang Bom-Dong Nai. The physical properties were determined based on mass ratio and bean’s dimension (lengh, width and thickness) as well as chemical (proximate) composition (total crude protein, ash, moisture, and lipid). These values were analysed using AOAC methods. The largest-size beans were found for the TD8 variety (1.5g of mass, 25.02mm of length, 14.28mm of width and 7.96mm of thickness). The moisture content of the cocoa beans was in the range between 5.64 and 6.99 (% wb) and the ash content in the range between 3.67% and 2.47% (wb). Noticeably, the fat content ratio (the most important value of cocoa bean) found in 8 varieties (TD1, TD2, TD5, TD9, TD11, TD12, TD13, TD14) was over 50%, thus these varieties are worthy chemical component especially for exported cocoa bean and industrized cultivation (extending the cultivation producing area).
Study on folate stability during thermal processing
Abstract | PDF
Stability of folate at different pH (3 to 9) toward thermal (65 to 140oC) treatments was studied on a kinetic basis. Residual folate concentration after thermal treatment was measured using reverse phase liquid chromatography. A model to describe the temperature effect on folate degradation rate constant is presented with the degradation of folates followed first-order reaction kinetics. The estimated Arrhenius activation energy (Ea) values of folate thermal degradation were determined.At all pH values studied, it was found that (i) folic acid and 5-formyltetrahydrofolic acid were more thermo stable than tetrahydrofolic acid and 5-methyltetrahydrofolic acid and (ii) all folates studied had the highest stability at neutral pH (pH 7.0) or alkaline pH (pH 9.2).
Isolation of three polymethoxylated flavones from Ageratum conyzoides L. growing in Can Tho city
Abstract | PDF
This paper introduces the extraction and purification of some polymethoxylated flavones from Ageratum conyzoides L., (Family-Asteraceae), growing in Can Tho city. Different extraction methods were used to study on the aerial part of the herb. From 1% HCl in water extracts, three polymethoxylated flavones have been isolated and identified. They were O‑methyl apigenin, sinensetin, and scutellareintetramethyl ether. Structures of isolated compounds were elucidated according to their 1H-NMR, 13C-NMR, HSQC, HMBC, MS spectra as well as referring to published article.
Social Sciences and Humanities
Evaluating public bus transportation services in Ho Chi Minh city, Vietnam
Abstract | PDF
Research on public transport, especially bus service, is very important since public transport affects all citizens and many social problems like reducing traffic jams, either improving energy efficiency or the environment, and mitigating private vehicles in urban areas. Despite the huge benefits of public transportation, the number of bus users in Ho Chi Minh City, Vietnam has been decreasing recently given the noticeably-deteriorated service quality and lack of satisfaction they derive from the services of public transport. The aim of this paper was to identify the important service elements and ridership’s demographic characteristics in determining passenger satisfaction. Ridership’s satisfaction with public transport services in Ho Chi Minh City had been investigated using binary logistic regression model. The finding showed that ‘availability of seats’, ‘ease of getting on and off the bus’, ‘cleanliness of vehicle interior’, ‘safety on crime while in the bus’, ‘price/cost charged’, ‘waiting time at bus station’, ‘frequency of service’, ‘information on transport routes and timetables’, ‘obey road laws’, ‘behavior of the bus driver and conductor’, ‘accuracy of announcement and information on services’, ‘customer care’, ‘gender’ and ‘income’ were found to be significant factors influencing passenger rating for overall service quality. In addition, the findings had implications for service providers, transport planners and authorities with regard to the implementation of the strategies to upgrade the bus service quality and increase passenger satisfaction.
Southeast asian studies as a field of study: A look from ideas behind the sociology of knowledge and inter-disciplinary debates
Abstract | PDF
Since the early 2000s, Southeast Asian economies have been emerging as an outstanding pillar in today’s globalizing world economy where the pressure to compete internationally has resulted in both an increase in academic efficiency that encourages inter-state and interdisciplinary collaborations and a resurgence of regional knowledge production to meet increasing demands of international businessmen, policy-makers and scholars who have begun to pay more attention to geo-politically important regions such as Southeast Asia. However, there is much contestation about the significance of Area Studies, unsolved contention between proponents of Area Studies and those of Disciplines, and the role of sociology of knowledge in facilitating Southeast Asian Studies as a field of study. This paper looks at the development of Southeast Asian Studies as a field of study which is characterized by the differences of the notion, scale and margin of “Southeast Asia region” across societies basically driven by the ideas behind sociology of knowledge approach. It then identifies and analyses major reasons fueling the existing tensions between Area specialists and skeptics as well as in what ways these tensions have been apparent. It is worth observing that the neo-liberalism progress, followed by deterritorialism, is assisting in increasing scholar mobility and closer collaboration between fields of research. This, as a result, paves the way for moderating the contemporary inter-disciplinary debates and increasing joint development though an international recognition of Area Studies in general does not seem to come by easily at the moment.