Chrysanthemum is a high commercial value plant, which is accounted for a large proportion of the total export of cut flowers in Vietnam. Therefore, the demand for seedling plants is very high. As a short-day plant, chrysanthemum requires supplemental lighting during the 2nd propagation stage in the autumn-winter period. This study aimed to evaluate the applicability of energy-saving LED lights to replace traditional lights in the propagation of some chrysanthemum varieties in Hanoi. The results show that the B3R7 660 nm LED (450 nm blue LED and 660 nm red LED combined in the ratio 7:3) was the most suitable for the 2nd propagation process in the greenhouse of 3 varieties (Pha le Chrysanthemum indicumyellow, Kim cuong C. morifolium cv Kim Cuong and Farm C. morifolium Hibiki). Plants grown under this LED light had a higher shoot multiplication efficiency than those under compact lamps (67.91, 18.47, and 26.89% respectively for Pha le, Kim cuong and Farm). Besides, the quality of seedlings is equivalent to chrysanthemums grown under compact lights. The power-saving efficiency when using LED light was approximate lower 55.21% compared to compact lamps.
Learning strategies have a strong effect on students’ success in foreign language learning. In fact, they are considered tools for active and self-directed engagement, which is vital for developing communicative competence. Language learning strategies also enable students to take responsibility for their own learning progress. This study was carried out to identify the preferred language learning strategies which are most frequently employed by non-English major students at Nong Lam University, Ho Chi Minh City, Vietnam. The research was conducted with 725 undergraduate students with a descriptive quantitative method. The data was collected using a Vietnamese questionnaire adapted from Strategy Inventory for Language Learning (SILL) originally developed by Oxford (1990). The Statistical Package for Social Sciences (SPSS) version 22.0 software was used to analyze the data obtained from the questionnaire. The findings revealed that non-English majors used language learning strategies at a medium level of frequency. They didn’t equally use all 6 strategies in their learning, which probably impeded their progress of language learning. The most frequently used strategies by the learners were metacognitive strategies, followed by memory, affective, cognitive compensation and social strategies as the least preferred ones. Pedagogical recommendations for lecturers are also discussed in the paper.
Bisphenol A (BPA) is a precursor chemical to produce polycarbonate plastics and epoxy resins that have been widely used in the world with many essential daily applications. BPA is considered one of the endocrine-disrupting chemicals in animals, which causes harmful effects on health. Besides, BPA originates from resins and consumer products after use has been released into the environment. To assess the contamination level of BPA in surface water, this study collected and analysed water samples from rivers and lakes in the centre of Hanoi. The average concentration of BPA in 45 surface water samples was 76.8 ng/l (6.6-284 ng/l). The highest concentration of BPA was found at the surrounding area of the wastewater treatment plant in Yen So (177 ng/l), followed by the Yen So lake (86.9 ng/l), To Lich and Nhue rivers (~80 ng/l), Lu, Set, Kim Nguu rivers (~60 ng/l) and the lowest level in West Lake (20.1 ng/l). The BPA levels in surface water were much lower than the predicted no-effect concentration (PNEC) which is used to assess the environmental risk to protect the aquatic organism from the European Union.
Spotted fever group Rickettsiae (SFG) and Scrub typhus infections, caused by obligate intracellular bacteria within two genera Orientia and Rickettsia SFG, the main host of which is the rodent. The study performed analysis of species composition of 103 rat samples collected at three provinces in Military Region 2 including: Dien Bien (35 samples), Son La (22 samples), and Phu Tho (46 samples), they have been collected from March to April, 2021, and detected the Rickettsia SFG and Orientia tsutsugamushi DNA by real-time PCR and nested-PCR. The results recorded that rat species belonged to Rattus flavipectus (42.7%), Rattus norvegicus (51.5%) were the most abundant, followed by Rattus germaini (3.9%) and Rattus nitidus (1.9%). The density of mice in Dien Bien was 6.7, Son La was 3.3, and Phu Tho was 8.5. The 6/35 (17.1%) positive samples for Rickettsia SFG were detected in Dien Bien by real-time PCR, in which 16,7% (5/30) was Rattus flavipectus and 50% (1/2) was Rattus norvegicus. In Son La, 7/22 samples were found as positive for Rickettsia SFG, accounting for 31.8%, of which 33.3% (3/9) was Rattus flavipectus, 30% (3/10) was Rattus norvegicus and 50% (1/2) was Rattus nitidus. In Phu Tho, 7/46 rats were found positive for Ricketsia SFG, accounting for 15.2% in which, Rattus norvergicus was 17.1% (7/41). However, among 103 rat samples, O. tsutsugamushi DNA was not detected by nested-PCR method. Currently, our results indicated the prevalence of Rickettsia SFG in Dien Bien, Son La and Phu Tho provinces.
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