Mosquitoes, in addition to being a biting nuisance, are vectors of several pathogenic viruses and parasites. As a continuation of our work identifying abundant and/or invasive plant species in Vietnam for use as ecologically friendly pesticidal agents, we obtained the essential oils of Blumea lacera, Blumea sinuata, Emilia sonchifolia, Parthenium hysterophorus, and Sphaeranthus africanus; analyzed the essential oils using gas chromatographic techniques; and screened the essential oils for mosquito larvicidal activity against Aedes aegypti and Aedes albopictus. The most active larvicidal essential oils were B. sinuata, which was rich in thymohydroquinone dimethyl ether (29.4%), (E)-β-caryophyllene (19.7%), α-pinene (8.8%), germacrene D (7.8%), and α-humulene (4.3%), (24-h LC50 23.4 and 29.1 μg/mL) on Ae. aegypti and Ae. albopictus, respectively, and Emilia sonchifolia, dominated by 1-undecene (41.9%) and germacrene D (11.0%), (24-h LC50 30.1 and 29.6 μg/mL) on the two mosquito species. The essential oils of P. hysterophorus and S. africanus were also active against mosquito larvae. Notably, B. sinuata, P. hysterophorus, and S. africanus essential oils were not toxic to the non-target water bug, Diplonychus rusticus. However, E. sonchifolia essential oil showed insecticidal activity (24-h LC50 48.1 μg/mL) on D. rusticus. Based on these results, B. sinuata, P. hysterophorus, and S. africanus essential oils appear promising for further investigations.

Peliosanthes crassicoronata is described and illustrated as a new species from southern Vietnam. It somewhat resembles P. macrostegia in having drooping bowl-shaped purplish flowers, but is readily distinguishable by the larger leaves with more numerous longitudinal veins, internally thickly ribbed staminal corona, and pistil with a hexagonal ovary and an indistinct style. The phylogenetic relationship of the new species was inferred from an analysis of chloroplast and nuclear DNA sequences.

Tóm tắtBê tông chất lượng siêu cao là một loại vật liệu xây dựng mới có nhiều tính năng cơ lý và kỹ thuật vượt trội so với bê tông truyền thống (bê tông thường), đã được nghiên cứu chế tạo và ứng dụng vào các công trình xây dựng, đặc biệt là công trình cầu, ở các nước tiên tiến từ những năm 90 của thế kỷ trước. Ở Việt Nam loại vật liệu này cũng đang ở giai đoạn nghiên cứu phát triển và ứng dụng thử nghiệm. Vì vậy việc nghiên cứu đánh giá hiệu quả kinh tế -kỹ thuật ứng dụng bê tông chất lượng siêu cao là rất cần thiết. Bài báo trình bày một nghiên cứu đánh giá hiệu quả kinh tế -kỹ thuật ứng dụng bê tông chất lượng siêu cao thông qua việc so sánh phương án sử dụng bê tông chất lượng siêu cao với bê tông thường để thiết kế và xây dựng cầu dân sinh An Thượng, thành phố Hưng Yên. AbstractUltra high performance concrete is a new construction material with many advantages of technical characteristic in comparison with normal concrete, which has been studied and applied in construction field, especially in bridge construction, in developed countries since the nineties of the last century. In Vietnam the Ultra high performance concrete is also studying and applying to experiment construction. So that it is very necessary to evaluate economic-technical efficiency of the Ultra high performance concrete. The article presents a study of economic-technical efficiency of the Ultra high performance concrete by comparing the alternative of Ultra high performance concrete usage to the alternative of normal concrete usage to construct An Thuong bridge in Hung Yen city.

Tripterygium wilfordii Hook.f. (Celastraceae), collected from Phia Oac-Phia Den National Park of Vietnam, is reported here as a new generic and species record for the flora of Vietnam. The genus Tripterygium differs from other genera of Celastraceae by its samara fruits, which become three-winged at maturity, and a scandent shrub. Taxonomic notes, descriptions, line drawing and photographs are provided, together with short notes on the distribution, ecology and phenology of Tripterygium wilfordii.

Two new species of Ophiopogon, O. dolichocaulis from Son La Province and O. trigonantherus from Cao Bang Province in northern Vietnam, are described and illustrated.  The former is similar to O. chingii, while the latter is similar to O. rupestris and O. dracaenoides. This paper not only details their taxonomic features and relationships to similar species but also provides ecological data on their habitats and phenology.