ASSESSMENT OF THE HEALTH AND ECOLOGICAL RISKS CAUSED BY FUNGICIDES IN CHRYSANTHEMUM CULTIVATION BY ENVIRONMENTAL IMPACT QUOTIENT

This study uses the Environmental Impact Quotient (EIQ) to assess the health and ecological risks caused by fungicides used in chrysanthemum cultivation upstream of Xuan Huong Lake, Da Lat city. Survey results reveal that 134 farmers use 21 fungicides with 18 active ingredients on a total area of 35.2 hectares. In all, 18 fungicides with an EIQ at the level of “unlikely to be hazardous” (EIQ < 25) are used on about 95% of the acreage, and 3 fungicides with an EIQ of “slightly hazardous” (25 < EIQ < 50) are used on the rest of the area. The Field Use EIQ of fungicide was rated very low in only 8.2% of the survey area and moderate in 48%. Areas with high and very high ratings account for 3% and 41%, respectively. Using fungicides according to the instructions can reduce the Field Use EIQ values in cultivated areas by 38% and return areas with high and moderate ratings to a low rating. Therefore, it is necessary to instruct farmers on the safe use of fungicides and to recommend those with low EIQ values for chrysanthemum cultivation

Stabilisation des sols traités à la chaux et leur comportement au gel

The present work deals with the behaviour of fine-grained silty and clayey soils treated with lime under frost. Those soils are frequently encountered in earthworks. Three soils corresponding to A1, A2, A3 classes according French NF P 11-300 standard were chosen for this study. These soils were treated with 3 lime dosages corresponding to three objectives: 1) improvement (minimum dosage), 2) stabilization and insensitivity to water (intermediate dosage), 3) stabilization and frost resistance (highest dosage). Lime-treated soils were subsequently cured for different times: 7, 28, 90, 365 days. Two frost processes, frost heave and freeze-thaw cycles, were applied in parallel with the assessment of mechanical, hydraulic and microstructural properties. Experimental results evidenced that it is the hydraulic properties (suction at frost front, sp and unsaturated hydraulic conductivity, kunsat) that govern the frost heave phenomenon of soils, treated or not. In addition, this study demonstrates the direct link between the microstructure (the pore size distribution) and the hydraulic properties (water retention curve and hydraulic conductivity). The treatment on one hand improves the mechanical performances of soils, and on the other hand modify their microstructure, and thus changes their frost sensitivity. The frost susceptibility increases directly after treatment, and then decreases with curing time. Based on the suction at frost front and the unsaturated hydraulic conductivity, a simple model was proposed and validated allowing to estimate the frost heave. Considering that the determination of unsaturated hydraulic conductivity is not a test commonly performed by most laboratories, a criterion based on the suction at frost front and the saturated hydraulic conductivity was proposed to estimate the frost sensibility of soils. The second frost resistance test consists of measuring the retained strength factor after 10 freeze-thaw cycles, RFT (%). The results obtained show that RFT of lime treated soil varies from 0% (when soil specimen completely loses its resistance and collapses after 10 freezethaw cycles) to 90%. When RFT is higher than 60%, no visual damage was observed on the specimen surface; consequently, this value is proposed as a criterion for acceptance of lime treated soil in capping layer before covering. In addition, the study of effect of freeze-thaw cycles showed a significant decrease of mechanical performance (RFT) during the first three cycles, and a stabilization after 10 cycles. Using X-ray Tomography, the intern damage of specimens due to freeze-thaw cycles was quantified. A correlation between the decrease of mechanical performance and the increase of damage index was evidenced. A model was then developed to evaluate the degradation of mechanical performance with the increase of damage indexOn s'intéresse dans le présent travail au comportement au gel des sols fins limono-argileux traités à la chaux seule, sols valorisables qui sont couramment rencontrés sur les chantiers de terrassement. Trois sols appartenant aux classifications A1, A2, A3 selon la norme NF P 11300, ont été choisis pour cette étude. Ces sols sont traités à 3 dosages en chaux correspondant à 3 objectifs : 1) amélioration (dosage en chaux minimal), 2) stabilisation et insensibilité à l'eau (dosage en chaux intermédiaire), 3) stabilisation et résistance au gel (dosage en chaux le plus élevé). Les sols traités sont ensuite conservés pendant quatre périodes de cure : 7 jours, 28 jours, 90 jours et 365 jours. Les deux processus de gel - le géligonflement et la gélifraction sont étudiés, parallèlement à l'évaluation des performances mécaniques, hydrauliques et microstructurales. Les résultats expérimentaux ont montré que les propriétés hydrauliques (la succion au front de gel, sp et la conductivité hydraulique à l'état non-saturé, kunsat) sont les paramètres qui gouvernent le phénomène de géligonflement des sols, traités ou non. Les résultats ont également mis en évidence le lien direct existant entre la microstructure (la distribution porale) et les propriétés hydrauliques du sol, principalement en termes de capacité de rétention d'eau et conductivité hydraulique. Le traitement augmente les performances mécaniques des sols d'une part, et amène d'autre part à des modifications de leur microstructure ; ceci induit des changements vis-à-vis de leur sensibilité au gel. Les sols sont plus gélifs directement après le traitement, cette sensibilité au gel diminuant avec le temps de cure. Une modélisation simple permettant d'estimer le gonflement au gel à partir de la succion au front de gel et de la valeur de conductivité hydraulique à l'état non-saturé a été proposée et validée. Vu que la détermination de la conductivité hydraulique à l'état non-saturé n'est pas un essai couramment pratiqué au sein de la plupart des laboratoires, un critère basé sur la succion au front de gel, sp, et la conductivité hydraulique à l'état saturé, ksat a été proposé pour évaluer la sensibilité des sols au gel. L'essai de gélifraction consiste à évaluer un coefficient de résistance de l'éprouvette de sol après 10 cycles de gel/dégel, RFT (%) - « retained strength factor after freeze-thaw testing ». Les résultats expérimentaux montrent que la valeur RFT des sols traités varie de 0% (lorsque les éprouvettes de sol perdent totalement leur résistance à la compression simple et sont détruites après 10 cycles de gel/dégel) à 90%. Quand RFT ≥ 60%, aucune dégradation visuelle de la surface des éprouvettes des sols traités n'est constatée. Ainsi, cette valeur est proposée comme critère d'acceptation des matériaux constitutifs d'une couche de forme subissant le gel avant son recouvrement. L'étude de l'effet du nombre des cycles de gel/dégel montre une diminution importante de la performance mécanique (RFT) durant trois premiers cycles de gel/dégel, et ce paramètre se stabilisant après 10 cycles. A l'aide de la technique de µ Tomographie X, l'endommagement interne des éprouvettes de sol ayant subi des cycles de gel/dégel a été quantifié. Une corrélation directe entre la diminution de performance mécanique et l'augmentation de l'indice de l'endommagement de l'éprouvette a été mise en évidence. Enfin, un modèle d'endommagement permettant d'évaluer la dégradation de la performance mécanique avec l'augmentation de l'indice d'endommagement a été établ

Evaluating model teacher education and training at Vietnam's universities of technology and education

The traditional educational paradigm has become outdated as a result of changes in both the cultural and socioeconomic setting. A more sustainable and acceptable teacher is needed in education. A quantitative study was conducted. 95 administrators and teachers at the University of Technology and Education participated in this study with the aim of analyzing the current status of the teacher education model at the institution. According to the findings of the study, the model for educator preparation has been put into practice primarily through the processes of planning, organizing and directing activities related to educator preparation as well as inspecting and assessing the quality of education. The outcomes of the study indicate that it is essential to design educational programs that are appropriate for the present context. In particular, the study suggests that one of the most important steps towards achieving success is to incorporate technology into teaching methods. The process of educating teachers with the right degree of expertise and skills should be emphasized by educators and policymakers by developing relationships with other educational institutions and allowing teachers to participate in internships

Depth of powers of edge ideals of Cohen-Macaulay trees

Let $I$ be the edge ideal of a Cohen-Macaulay tree of dimension $d$ over a polynomial ring $S = \mathrm{k}[x_1,\ldots,x_{d},y_1,\ldots,y_d]$. We prove that for all $t \ge 1$, $$\operatorname{depth} (S/I^t) = \operatorname{max} \{d -t + 1, 1 \}.$

ASSESSMENT OF THE HEALTH AND ECOLOGICAL RISKS CAUSED BY FUNGICIDES IN CHRYSANTHEMUM CULTIVATION BY ENVIRONMENTAL IMPACT QUOTIENT

This study uses the Environmental Impact Quotient (EIQ) to assess the health and ecological risks caused by fungicides used in chrysanthemum cultivation upstream of Xuan Huong Lake, Da Lat city. Survey results reveal that 134 farmers use 21 fungicides with 18 active ingredients on a total area of 35.2 hectares. In all, 18 fungicides with an EIQ at the level of “unlikely to be hazardous” (EIQ < 25) are used on about 95% of the acreage, and 3 fungicides with an EIQ of “slightly hazardous” (25 < EIQ < 50) are used on the rest of the area. The Field Use EIQ of fungicide was rated very low in only 8.2% of the survey area and moderate in 48%. Areas with high and very high ratings account for 3% and 41%, respectively. Using fungicides according to the instructions can reduce the Field Use EIQ values in cultivated areas by 38% and return areas with high and moderate ratings to a low rating. Therefore, it is necessary to instruct farmers on the safe use of fungicides and to recommend those with low EIQ values for chrysanthemum cultivation

Effect Of Promotion On Customers’ Trust Organic Food In The Mekong Delta

The customer’s trust is seen as a key for the survival to any enterprises wanting to maintain sustainably in the competitive market at present time. Enterprises need to experience ceaseless efforts to gain their customer’s trust. In addition, the quality of the product, there are many other factors contributing to build and strengthen the trust of consumers. This study is to determine factors of marketing activities which have impacts on the trust of organic food in The Mekong Delta. The study was conducted with two promotion tools (advertisement and PR), surveyed 300 subjects in the Mekong Delta region, Vietnam. Descriptive statistics, EFA analysis and MLR regression analysis were used to find the advertisement and PR’s impact on the customer’s trust. The analysis results showed, form of public relations, the usefulness of public relations activities, the quality of information from public relations activities have great impacts on customers’ trust. This means that when the customer feels good about the above-mentioned factors, the higher the trust they have on the product. Based on the results, the author proposed solutions to gain greater trusts from customers. For instance, it is necessary to have a careful study on target customers’ psychology, preferences and habits when they approach advertising media and their perceptions of the frequency of advertising. The enterprises need to provide advertising information in a full and honest manner. They should develop PR programs that focus on usefulness for the target audience and the community

Antibacterial activity of Piper betle extracts on Helicobacter pylori and identification of potential compounds

Helicobacter pylori is one of the most common infectious bacteria in the world that causes gastric diseases leading to cancer. The increase of multiple antibiotic resistance rates of H. pylori have been reported worldwide. Thus, development of novel drugs is urgently required. Piper betle has many therapeutic values in traditional medicine. In this study, therefore, we investigated antibacterial activity of P. betle extracts and their fractions against a H. pylori strain isolated in Vietnam. The agar disk diffusion assay showed inhibition zone of ethyl acetate extract and methanol extract from P. betle leaf that of were 46 mm and 32 mm in diameter, respectively. After fractionation of the ethyl acetate extract through silica gel column chromatography, two peaks, PD2 and PD3, out of 12 fractions showed the strongest antibacterial activity. PD2 was sub-fractionated further by re-chromatography on the silica gel column, and subfraction TK12 gave best resolution on LC-MS analysis. Finally, 4 potential compounds, quercetrin, calodenin B, vitexin and plicatipyrone, were identified in TK12 fraction.

EVALUATION OF SOLAR RADIATION ESTIMATED FROM HIMAWARI-8 SATELLITE OVER VIETNAM REGION

The development of Solar energy system is growing rapidly in Vietnam in recent years by encouragement of the Government in renewable energy. Requirement for accurate knowledge of the solar radiation reaching the surface is increasingly important in the successful deployment of Solar photovoltaic plants. However, measurements of different components of solar resources including direct normal irradiance (DNI) and global horizontal irradiance (GHI) are limited to few stations over whole country. Satellite imagery provides an ability to monitor the surface radiation over large areas at high spatial and temporal resolution as alternatives at low cost. Observations from the new Japanese geostationary satellite Himawari-8 produce imagery covering Asia-Pacific region, permitting estimation of GHI and DNI over Vietnam at 10-minute temporal resolution. However, accurate comparisons with ground observations are essential to assess their uncertainty. In this study, we evaluated the Himawari-8 radiation product AMATERASS provided by JST/CREST TEEDDA using observations recorded at 5 stations in different regions of Vietnam. The result shows good agreement between satellite estimation and observed data with high correlation of range 0.92-0.94, but better in clear-sky episodes.Because of AMATERASS outperform, we used it for validating ERA-Interim reanalysis in the spatial scale. The comparison was made dividedly for 7 climate zones and 4 seasons. The conclusion is that ERA-Interim is also well associated with satellite-based estimates in seasonal trend for all season, but in average the reanalysis has negative bias towards satellite estimates. This underestimation is more pronounced in the months of JJA and SON periods and in the north part of Vietnam because of unpredicted cloud in the ERA reanalysis

A SURVEY ON THE DIFFICULTIES IN WRITING ESSAYS OF ENGLISH MAJORED SOPHOMORES AT TAY DO UNIVERSITY, VIETNAM

This thesis “A study on the difficulties in writing essays of English-majored sophomores at Tay Do University” was conducted to examine the difficulties that second-year students majoring in English often met in writing essays. For this purpose, the participants in this study were 100 English majored sophomores in classes 14A, 14B and 14C at Tay Do University. The interview with 3 extended statements for English majored teachers and a questionnaire with 25 closed statements for students is used as instruments to collect the data. The data from the interview and questionnaire were collected to make clear and prove the problems that the students have had in writing essays. The study figured out some difficulties about background knowledge, vocabulary, grammar structure, idea arrangement and orthography in writing essays faced by English majors sophomores at Tay Do University. Besides, this study also helps students realize their challenges and improve their writing essays.  Article visualizations

Effects of hormone and fertilizers on early flower induction of Dendrobium anosmum hybrid seedlings under ex vitro condition

Early flowering of new orchids is important to save time for selecting valuable flowers and artificial induction of flowering is a critical consideration in the orchid production industry. In this study, a new Dendrobium anosmum hybrid was generated by cross-breeding between D. anosmum ‘Chau Nhu’ and D. anosmum ‘Di Linh’. The ancestors and hybrid seedlings from in-vitro culture were trained in the net house and their growth and flowering were evaluated under ex vivo conditions with specific fertilizers and hormones. The results suggest that the hybrid plants grew better than their parents in terms of stem height, stem diameter, and leaf number. Growth hormones were applied to stimulate early flowering in matured hybrids and it was discovered that ‘Keiki pro’, a commercial hormone product, produced the best results, with a flowering rate of 66.67% after two applications. Hybrid flowers varied in width from 36.36% (3.0-6.0 cm) to 63.64 % (more than 6.0 cm) from ancestral width in medium-sized and large-sized flowers, respectively. Also, the hybrid flower colours was mostly a combination of pink/violet (75C) and purple/pink (68A), which is different from their parents. Importantly, the dorsal sepal, petal colours, and shape of hybrid flowers varied significantly among individual hybrids, between hybrids and their progenitors. Some mutations in the lips and columns of the novel hybrid flowers were also visualized. Hence, the D. anosmum hybrid seedlings successfully induced flowers after a year of culture under optimal hormones and fertilizers conditions. The results can serve as a critical reference for the early flowering of the orchid seedlings