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Eight compounds, including 20(R)‐ginsenoside Rg3(1), Ginsenoside Rd (2), ginsenosides Rg2(3), ginsenosides Re (4), β‐sitosterol (5), daucosterol (6), stigmasterol (7), and stigmasterol‐3‐O‐β‐glucoside (8) were isolated from the Panax ginsengsprouts cultivated in Vietnam. Their structures were elucidated by 1H, 13C NMR, and MS spectroscopic techniques and compared with the previous publication. In addition, their inhibitory activity on NO production and cytotoxic effects against human embryonic kidney cells (HEK‐293A) and human hepatocellular carcinoma (HepG2) were evaluated. This is the first study of the phytochemical investigation of P. ginsengsprouts cultivated in Vietnam and ginseng sprouts also contained the same main active ginsenosides as in the 4–6‐year old roots.

Five flavonoids, including quercetin (1) and four its derivatives, quercitrin (2), isoquercitrin (3), astibin (4), and rutin (5), together with two phenolic glycosides, 3,3′‐di‐O‐methylellagic acid 4‐O‐β‐D‐xylopyranoside (6), and aesculin (7) were isolated from the whole plants of Macrosolen bidoupensisTangane & V.S. Dang. Their chemical structures were characterized using HR‐ESI‐MS, NMR data and comparison with published data. Compounds (3, 4& 7) were notified from the Macrosolengenus for the first time, whereas, all isolated compounds were informed for the first time from this species.

The hard and soft magnetic nanoparticles of Mn-(Bi, Ga) and Fe-Co, respectively, were prepared by using a high energy ball milling method. These nanoparticles were then mixed together with different ratios and subsequently annealed in various conditions of temperature and time to make nanocomposite magnets. The coercivity Hcand maximum energy product (BH)maxof these magnets depend on the nanoparticle size and on the ratio of the hard/soft magnetic phases. The annealing process plays an important role for exchangecoupling between the hard and soft magnetic phases. With sizes in a range of 40-60 nm, the Mn-(Bi,Ga) nanoparticles reveal high coercivity (Hc> 12 kOe) to be a potential rare-earth-free hard magnetic phase for producing nanocomposite magnets. Quite high coercivities, Hc> 4 kOe, and maximum energy products, (BH)max> 4 MGOe, have been achieved for this kind of rare-earth-free nanocomposite magnets.

The authors attempt to optimize for performance the composition of R2Fe14B/Fe3B-based hard nanocomposite alloys with R= neodymium (Nd) and terbium (Tb) by optimizing phases in order to develop hysteresis parameters such as maximum magnetization, coercivity and maximum energy product through variation in composition and heat treatment. The samples were prepared from arc-melted ingots of different compositions. The crystallization temperatures were obtained from the differential scanning calorimeter traces of the samples with the composition Nd4−xTbxFe71Co5Cu0·5Nb1B18·5(x= 0·0, 0·2, 0·4, 0·6, 0·8 and 1·0). Depending on their crystallization temperatures, the samples were annealed at 600, 625, 650, 675 and 700°C for 10 min. Amorphosity and crystallization behavior were studied by X-ray diffraction using copper (Cu) Kαradiation (1·5418 Å). The Mössbauer spectra of all the samples were recorded at room temperature by using iron-57 (57Fe) Mössbauer spectrometry in transmission geometry with a constant-acceleration spectrometer. Magnetic properties were determined by a vibrating-sample magnetometer in the as-cast and annealed conditions. Although the highest values of coercivity and remanent ratio were found to be 4·18 kOe and 0·72, respectively, for the sample of composition Nd3Tb1Fe71Co5Cu0·5Nb1B18·5annealed at 650°C with a higher concentration of terbium, the highest maximum energy product was determined to be 12·67 MGOe for the sample of Nd3·8Tb0·2Fe71Co5Cu0·5Nb1B18·5.

Objectives Isolation, structure determination, and antimicrobial activities evaluation of compounds from the methanol extract of the marine microalga Thraustochytrium pachydermumTSL10.Methods Using chromatographic methods to isolate compounds from the methanol extract of the T pachydermum. The chemical structures were elucidated by analyses of HR-ESI-MS and NMR spectral data. The antimicrobial activities of compounds were evaluated using the dilution turbidimetric broth method as the standard protocol published by the Clinical and Laboratory Standard Institute.Results One new sterol, (24R)-ergosta-7,22-diene-3β,5α,9α-triol (1), and 16 known compounds, ergosta-7,22-diene-3β,5α-diol (2), cerevisterol (3), (22E,24S)-5α,6α-epoxy-ergosta-8(9),22-diene-3β,7α-diol (4), ergosterol (5), 5α,8α-epidioxyergosta-6,22-diene-3β-ol (6), linoleic acid (7), 4-((9Z,12Z)-octadeca-9,12-dienoyloxy)butanoic acid (8), 1-linoleoyl-sn-glycero-3-phosphocholine (9), cibotiglycerol (10), gingerglycolipid B (11), oleic acid (12), 4-((9Z)-octadec-9-enoyloxy)butanoic acid (13), (2S)-1-O-(9Z)-octadec-9-enoyl)-3-O-(6-sulfo-D-quinovopyranosyl)glycerol (14), 6′-O-linoleylsucrose (15), gingerglycolipid C (16), and (S)-3-stearoyl-sn-glycerol (17) were identified from the marine microalga Thraustochytrium pachydermumTSL10. Sterols 1–6were found to exhibit significant antimicrobial activities on Gram-( + ) bacteria (Enterococcus faecalisATCC29212, Staphylococcus aureusATCC25923, and Bacillus cereusATCC14579) and the yeast (Candida albicansATCC10231) with MIC values ranging from 32 to 256 µg/mL.Conclusions The results suggested sterols 1–6could be potential antimicrobial agents against Gram-( + ) bacteria.

AbstractThis study evaluated nutrients removal from domestic wastewater by five plants in wetland roof systems (WR). The study plants include Arachis duranensis(1), Evolvulus alsinoides(2), Cosmos Bipinnuatus(3), Cyperus alternifoliusLinn (4), and Philodendron hastatum(5). The WRs were acclimatized at hydraulic loading rates (HLR) of 220 m3/ha d and operated at HLR of 300 m3/ha d. The plants (1), (2), (4), and (5) had the ability to grow under the rooftop conditions with domestic wastewater as a nutrient source while the plant (3) was not suitable and dead after 20 d of operation. Generally, A. duranensis(1) and C. alternifoliusLinn (4) were the most suitable plants treating domestic wastewater under the conditions of WR. The average phosphorus removal efficiencies of (1) and (4) were approximately 75 and 89%, respectively, while the average nitrogen removal efficiencies were 69 and 92%. The phosphorus accumulation in plants (1) and (4) during operation was 20.4 and 29.4%, respectively, while the nitrogen accumulation was 21.5 and 93%. It is concluded that C. alternifoliusLinn (4) has best nutrient removal among the study plants under the conditions of shallow bed WR treating domestic wastewater (24 ± 4 and 2.0 ± 0.4 kg TP/ha d).

Two new (1and 2) and six known (3-8) compounds were isolated from the methanolic extract of the Vietnamese marine spider conch Lambis lambisLinnaeus, 1758. Based on comprehensive spectroscopic analyses, particularly HRESIMS, and 1D- and 2D-NMR spectra, their chemical structures were determined to be 25,26,27-tri-nor-cholest-5-ene-2β,3α,24-triol-2,24-disulfate (1), 25,26,27-tri-nor-cholesta-2β,3α,24-triol-3,24-disulfate (2), 25,26,27-tri-nor-cholesta-2β,3α,24-triol-2,3,24-trisulfate (solomonsterol A, 3), 1-O-arachidonoyl-3-O-stearylglycerol (4), eicosapentaenoic acid (5), adenosine (6), adenine (7), and uracil (8). This is the first report of compounds 3-8from L. lambis.

AbstractThe contaminated water is a main source of many waterborne diseases such as cholera, typhoid, etc. causing many serious public health crises, especially in developing countries with the low hygiene condition. In Vietnam, previous studies have reported that industrial and domestic waste cause adverted pollution on Saigon River that supplies water for 30% of 10 million residents in Ho Chi Minh City. Annual monitoring water quality data during 2006–2011 showed that concentration of ammonia and organic matter has been significantly increased and over the allowable limit (COD > 10 mg/L). In order to reduce these pollutants in the finished water and for disinfection, a large dose of chlorine (about 3–6 mg/L) needs adding in the treatment process at Tan Hiep water treatment plant. A negative effect of using too much chlorine is the formation of disinfection by-products (DBPs) such as trihalo-methanes (THMs) and haloacetic acids (HAAs). The concentration of THMs in finished water of Tan Hiep plant ranged from 50 to 200 μg/L. In this study, a pilot-scale plant using Ozone/UV process combined with biological activated carbon filter (BAC) was studied on eliminating the organic matters and the DBPs formation in drinking water. With the feed water taken after sedimentation, the combination of Ozone/UV–BAC proved to be very effective in TOC, DOC, UV254, and SUVA removals with percentage reduction of 19.1, 17.6, 30.7, and 16.4%, respectively. The removal efficiency of the combined process was always higher than the sum of treatment efficiency of each process (Ozone/UV or BAC) alone. It was confirmed that the pretreatment of Ozone/UV could help to increase the organic removal of BAC filter. According to the organic reduction, the concentration of DBPs in water has decreased considerably with 70.6% (THMs) and 67.7% (HAAs) removal. DBPs formation potential decreased 39.3% (THMFP) and 46.1% (HAAFP).

AbstractWetland roof (WR) system was developed to apply for building terrace and top roof in the urbanized area of Ho Chi Minh City. This study aims to improve the green area of the city and to treat domestic wastewater through a shallow horizontal subsurface constructed wetland that is located in a household roof. The pilot-scale unit of horizontal subsurface flow WR system with Melampodium paludosum, an indigenous emerging plant in Vietnam, was experimented at the average hydraulic loading rate (HLR) of 338 m3/ha d (∼36 kg COD/ha d) corresponding to HRT of 18 h. The treatment performance was not significantly different for rainy and sunny days at various HLRs. It was observed that the average removal efficiency of COD was 77–78% or 20–28 kgCOD/ha d for both sunny and rainy days. It is apparent that nutrient removal was greatly achieved as indicated by TN removal efficiency of 88–91% or 17–20 kg TN/ha d. In addition, TP removal reached 72–78% or 1.6 kg TP/ha d for different HLRs. The treated effluent could comply with the standard limits of Vietnam national technical regulation for domestic wastewater. It was also observed that the growth rate of M. paludosumwas 0.1 cm/day in length. The ratio between nitrogen uptake by plants over nitrogen removed by WR was 0.13, while the higher ratio of 0.68 was obtained for the case of phosphorus. The temperature of WR units was 4 ± 1°C lower than that on concrete floor that likely help saving energy for building cooling if applying WR on the top roof. Based on the experimental results obtained to date, the WR system would be a promising system for domestic wastewater treatment especially for urbanized city, where green area is of high demand.

Nd-Fe–Al–Co alloys with thickness of 0.05–4 mm were prepared by means of rapid solidification methods, suction-casting and melt-spinning, and investigated using X-ray diffraction, electron microscopy and magnetization measurements. With appropriate composition and quenching rate, the alloys behave as single-phase hard magnetic materials. Coercivity of the alloys can reach 7.6 kOe at room temperature and exceed 30 kOe at 100 K. When the thickness of the alloys is increased, multi-magnetic phase behavior is clearly performed and Nd2Fe15Al, NdAl2, Nd3Al and Nd phases are further crystallized. The optimal hard magnetic properties of the alloys closely related to a microstructure which consists of nanocrystallites with size of 10–30 nm dispersed in an amorphous matrix. The hard magnetic phase in the alloys belongs to the amorphous phase. The nanocrystallites, whose total volume fraction is very small in comparison with that of the amorphous phase, probably act as pinning centers, resulting in high coercivity behavior of the alloys.

The influence of composition and annealing temperature on the magnetic properties of (Nd0.5Pr0.5)6+xNb1.5Fe88.5–x–yB4+y(x= 0–6, y= 0–10) nanocomposites prepared via melt-spinning and subsequent annealing was investigated systematically to obtain their optimal compositions and fabrication conditions. The results show that each of the rare earth concentrations has an appropriate ratio of Fe/B to reveal the best performance of the material. The optimal annealing temperature decreases from 750 to 675°C when concentration of rare earth is increased from 6 to 12 at.%. Coercivity, Hc, and maximum energy product, (BH)max, of these nanocomposites can be regulated up to 14.5 kOe and 16 MGOe, respectively, by suitably choosing their composition.

AbstractThe present study aims to assess the treatment efficiency and membrane fouling propensity of a submerged membrane bioreactor (MBR) treating dyeing and textile wastewater by introducing Powder-Activated Carbon (PAC) and Alum (called “fouling reducer”). The treatment performance and fouling behavior of MBR when adding PAC and Alum were compared to those of the control MBR. The components of dyeing and textile wastewater were fluctuated with Chemical oxygen demand (COD), color, and turbidity of 500–2,500 mg/L, 370–2,700 Pt-Co, and 50–370 NTU, respectively. The Mixed Liquor Suspended Solids (MLSS) concentration in an MBR fluctuated from 6,000 to 9,000 mg/L. The mixed liquor volatile suspended solids (MLVSS) to MLSS ratio was 0.76. The organic loading rate was operated in the range of 1.4–1.7 kg COD/m3 d. In the control MBR (without the addition of a fouling reducer into the bioreactor), the results showed that the MBR could only remove the color at a maximum efficiency of 50% and COD of 60–94% during the operation time. The trans-membrane pressure (TMP) increased from 2.1 to 4.4 kPa during 30 days of operation. When PAC and Alum were introduced into the MBR at the concentrations of 1,000 and 40 mg/Lsludge, respectively, the two compounds helped to enhance the removal efficiency of the COD, color, and fouling control. The treatment performance of the MBR and the fouling propensity were noticed to be much improved, compared to the control MBR. The efficiency to remove color was 40–80% and 80–90% for PAC and Alum, respectively. There is a significant difference in the COD removal efficiency between the addition of PAC and Alum. While the removal efficiency of COD removal ranged from 50 to 94% for PAC, it was stable at around 80–90% for Alum during the operation. Generally, the fouling mitigation of PAC and Alum was almost similar and even much effective compared to the control MBR. The TMP increased slowly from 2.2 to 2.9 kPa to 2.4 to –3.0 kPa in PAC and Alum in 22 days of operation. This fact reveals that Alum and PAC were excellent substances in fouling control, COD, and color removal for MBR treating the dyeing and textile wastewater.

AbstractSince the end of the 1990s, Hanoi City has instituted a program of urban upgrading. This program aims at improving the living conditions of residents who are living in dilapidated public housing areas (PHAs) which were constructed forty years ago. However, the upgrading implementations are very slow and are challenged by various obstacles, difficulties, and problems. This study is expected to provide opinions to help policy makers in reviewing upgrading mechanisms and policies in connection with upgrading plans and designs. Through findings from interviews with a total of 120 households in the Kim Lien and Giang Vo PHAs, the authors found that: (i) the majority of residents are positive in support of upgrading projects; (ii) most residents want to have resettlement flats at the same location; (iii) most residents prefer to buy flats rather than to rent them when the upgrading project is completed; (iv) a relatively high percentage of residents continue to lack official information about upgrading projects. Discussion on upgrading projects, measures and solutions should be made transparent to the public and related residents should be informed about the process. Successful upgrading projects require a high level of consensus by the residents.

During the rainy season in extensive river floodplains and deltaic lowlands, floods lasting several months render the land unavailable for crop production for several months each year. These waters are considerably underutilized in terms of managed aquatic productivity. This raises the opportunity to enclose parts of these annually occurring floodwater areas to produce a crop of specifically stocked aquatic organisms aside from the naturally occurring ‘wild’ species that are traditionally fished and are not affected by the culture activity, overall resulting in more high-quality, nutrient-dense food production and enhanced farm income for all stakeholders, notably the poor. The WorldFish Center and its national partners recently tested two systems in a community based management approach in Bangladesh and Vietnam: (i) concurrent rice-fish culture in shallower flooded areas, and (ii) alternating rice and fish culture in the deep-flooded areas. Results indicate that community-based fish culture in rice fields is technically feasible, economically viable and socially acceptable. It can increase fish production to about 600 kg/ha/year in shallow flooded areas and up to 1.5 t/ha/year in deep-flooded areas, without reduction in rice yield and wild fish catch. For the overall system and in the trials conducted, an additional income of US$135 per ha in southern Vietnam, and up to US$437 per ha in Bangladesh were achieved, which is an increase of 20%to 85% over the previous profitability. The communities neighboring the trial sites have been adopting the technologies widely.