Tạp chí Khoa học Tự nhiên Đại học Quốc gia Thành phố Hồ Chí Minh

In Vietnam, the Cai river basin - Phan Rang in Ninh Thuan province is considered to tolerate the most serious drought, which has influenced seriously on the lives and economy of the people in the region. Using Multi-Criteria Analysis method - MCA integrated with GIS for eight factors: evaporation (ETo), rainfall, groundwater, surface water annual flow module, vegetable matter (NDVI), river density, humidity of land and slope to build a system of component maps identifying the level and the change of drought, namely meteorological one in the Cai river basin - Phan Rang, Ninh Thuan province each year. According to the average results of the study period (2000–2014), the drought at this region has 3 levels: medium drought with 0.05 %, severe drought with 80.90 %, very severe drought with 19.05 % of the studied area. At the same time, the value of factors: evaporation (ETo) is from 1417.02–1817.00 mm, rainfall is from 640.9– 910.8 mm, groundwater is from 0–11 (1/s/km2), surface water annual flow module is from 9 – 23 (1/s/km2), vegetable matter is (NDVI) from -0.4 – 0.6, river density is from 0–1.6 km/km2, humidity of land is from 3.65–55 % and slope is from 0o– 62.8o. This study focuses only on the meteorological drought, we need more detailed researchs to continue estimating the 3 types of drought (agricultural, hydrological, socio-economic) to be able to recognize drought in this region more fully, thereby giving effective measures against drought.

Weak anion exchange sorbent based on cross-linked polystyrene with primary secondary amine group was prepared by substitution nucleophilic reaction (SN2) between methylene chloride group and 1,2-ethylene diamine. The effect of factors, namely the weight ratio of amine over methylene chloride, reaction time and temperature on nitrogen percentage were studied using experimental design approach. The amination yield rose as all of factors increased but was reduced while both temperature and time increased simultaneously. Nitrogen percentage of the products were varied from 4.0% to 6.3%. Sorbents with predicted capacity of 4.5%, 5.0%, 6.3%, and 6.5% were synthesized. The results showed that the actual capacities of the products were close to the predictions, especially for those in the experimental domain, indicating a good model that can be used to prepare sorbents of any desired capacity. The sorbent application ability of multiresidue pesticides analysis in food were initially investigated through both aspects: interference elimination and analyte content conservation.

The granite of the Song Ma block mainly consists of two types of granite: biotite granite and hornblende-biotite granite. Biotite granites have the percent of plagioclase (35– 45%), K-feldspar (25–35%), quartz (~20%) and biotite (~10%). Biotite-hornblende granite with the content of plagioclase (40–50%), Kfeldspar (10–15%), hornblende (5–10%) and biotite (5%). Zircon crystals were selected from the granite of Song Ma block are V0741, V0856 and V1006 samples with the LA-ICPMS U-Pb analyses gave concordant ages concentrated at 257±4Ma, 262±3Ma and 241±6Ma (weighted mean). Those ages are older than the results of the previous research. The mineral assemblages and geochemical characteristics show the typical of I-type granites. The results of Hf isotope composition analysis give the value of εHf(t) from +7.3 to +13.9, which is proven the sources of the granite Song Ma block similar to the granite of Phan Si Pan zone, NW Viet Nam during the period from late Permian to early Triassic.

The essential oil is a main product of Holy basil (Ocimum sanctum L.). It present mainly in the peltate glandular trichomes. Therefore, the morphological and physiological changes during the development of peltate glandular trichomes are of great interest. In this paper, the morphological changes of glandular trichomes, the relationship between glandular trichomes and leaf development, and the physiological changes during leaf development of Holy basil were analyzed. The Holy basil peltate glandular trichomes were formed at the early stage of leaf development (leaf primordia) and continuously renewed during leaf development. The development of peltate glandular trichomes of Holy basil included four main stages: initiation, shaping, secretory cavity formation and essential oils accumulation. The formation of peltate glandular trichomes started at the beginning of leaf rapid growth while the accumulation of essential oils occurred at the slow mature growth and strongly increased at the stationary growth phase. The intensity of photosynthesis and respiration of leaves increased strongly during the period of rapid growth. The activities of auxins and cytokinins in leaf were very high at the beginning of the rapid growth stage while gibberellin activity was high only at the end of the rapid growth stage. Treatment with 1 mg/L gibberellic acid increased the length of branch, area of leaf, and the content of the essential oil.

Electroencephalographic (EEG) signals have usually been affected by different types of noise as 50 Hz noise, mechanical noise caused by body movements, heart disturbance, eye noise... In this paper, methods such as: independent component analysis (independent component analysis-ICA), discrete wavelet transform and design of digital filters, were used to filter the noises, to classify the basic components for EEG signals. Then the mean of energy value was calculated to identify the status of the EEG signals such as blink, thoughts, emotion, smoking and blood pressure. The results of calculations and simulations of signals EEG could demonstrate the efficiency of the method.

A combination between the nanostructured photocatalyst and cellulose-based materials promotes a new functionality of cellulose towards the development of new bio-hybrid materials for water treatment and renewable energy applications. In this study, nanocellulose (CNC) was synthesized from sugarcane bagasse (SCB) biomass via formic /peroxyformic acid process treatment and acid hydrolysis at an atmospheric pressure. The resulting CNC of sugarcane bagasse were characterized by crystallinity index, chemical structure and morphology. X-ray diffraction (XRD) analysis revealed that the crystallinity increased with successive treatments. Images generated by TEM showed that CNC was rod-like in morphology, average diameter and length of 10 nm and 410 nm, respectively. The obtained CNC was used as a biotemplate for the synthesis of copper oxide (CuO) nanostructures through in - situ solution casting method. The photo-Fenton catalytic activity was evaluated via the degradation of methylene blue under sunlight irradiation with H2O2 as a oxidizing agent. The methylene blue degradation ratio of CuO/ CNC composite could achieve 98% in 150 min. The addition of H2O2 enhanced photocatalytic activities of the CuO/CNC. H2O2 not only prevented the recombination of charge carriers by accepting the photogenerated electrons and holes effectively but also produced additional OH.

This work aimed at calculating and assessing sensitivity (S) to the climate change (CC) of the rural fresh water and sanitation (RFWS), a case study in Can Gio for the period of 2014 – 2025, by index (via 12 indicators), survey, and professional adjustment methods. Results showed that, in 2014, the S index of the whole district was 40.7 (medium low level), ranging from 29–58 among 7 communes (according to medium low to medium high levels). Binh Khanh had the highest S index, 58 points (2014), followed by An Thoi Dong, Tam Thon Hiep, and Long Hoa. For the period of 2020–2030, S indices of the district tend to decrease (35.3 and 33.9, respectively), ranging from low to medium low levels among the communes. This work also reviewed strengths and weaknesses in the sensitivity to CC of RFWS in the local, pointing out and prioritizing 7 defected links as the basis for establishing solutions to mitigate the S to CC of the system, serving the sustainable development objectives of the local.

Thermal comfort is a parameter to assess environmental indoor quality which affects especially performance of students. A cross-sectional study was conducted in classrooms at a university campus in Ho Chi Minh City to assess the thermal condition during the class time. Microclimate parameters were measured at the same time when students answered the survey on their thermal sensation and acceptability of the indoor climate. Objective data analysis from adaptive PMV model for non-air-conditioned buildings revealed that none of classes had the thermal condition were in the comfort zone of TCVN 7438:2004, coinciding with the subjective result from the surveys. The research showed that 72 percent of the 472 students did not accept the thermal environment and 91.3 percent of students preferred cooler. The suggested neutral temperature was 29.4 oC, the derived from the linear regression between adaptive Predicted Mean Vote (aPMV) and operative temperature (To).

In this study, NaCl at varrious concentrations of 4 – 10 g/L was used to investigate the salt tolerance of in vitro shoot cuttings of Chrysanthemum indicum. Morphological, physiological and biochemical changes during the response of shoot cuttings in the salinity stress were analyzed. NaCl at 6 g/L reduced the development of shoot cuttings. Under salinity stress conditions, there have just a little reduction of the chloroplast in parenchymal cells near the midrib of leaf before they turn brown and die. Besides, carotenoid, starch content, and photosynthesis intensity were decreased. In contrast, respiration rate, proline and total soluble sugar content, and the activity of IAA and gibberellin were strongly increased. The application of IAA 0.25 mg/L, zeatin 0.1 mg/L and GA3 0.1 mg/L improved the shoot development in the salinity stress condition. Shoots in MS medium supplemented with BA 0.2 mg/L, NAA 2 mg/L and NaCl 6 g/L grow better in salinity stress condition.