Abstract: This paper presents new data on the orchid diversity of Vietnam obtained from field explorations made mainly in 2015–2022, as well as from the study of some historical collections housed at the Herbaria of Russia and Vietnam. It includes descriptions of two species new to science (Coelogyne phitamii and Cymbidium sangii), reports of one genus (Stigmatodactylus), and eleven species new to the flora of Vietnam (Coelogyne fuliginosa, C. suaveolens, Cremastra malipoensis, Cymbidium cochleare, C. goeringii, C. macrorhizon, Holcoglossum nagalandense, Miguelia shenzhenica, Otochilus lancilabius, Pelatantheria bicuspidata, Stigmatodactylus sikokianus). Three new nomenclature combinations (Biermannia averyanovii (Vuong, Kumar, V.H.Bui & V.S.Dang.) Aver., Miguelia shenzhenica (Z.J.Liu & S.C.Chen) Aver., Panisea sondangii (Vuong, Aver. & V.H.Bui) Aver.) and lectotypes for three species (Coelogyne suaveolens, Otochilus lancilabius, Pelatantheria bicuspidata) are proposed. Data on accepted names, main synonyms, etymology (for newly described species), morphological description, studied specimens, ecology, phenology, and distribution, conservation status assessment according to IUCN Red List Categories and Criteria, brief taxonomic notes, and illustrations are provided for each species listed.

Abstract: In this paper, we analyze an underlay two-way decode-and-forward scheme in which secondary relays use successive interference cancellation (SIC) technology to decode data of two secondary sources sequentially, and then generate a coded signal by superposition coding (SC) technology, denoted as SIC-SC protocol. The SIC-SC protocol is designed to operate in two time slots under effects from an interference constraint of a primary receiver and residual interference of imperfect SIC processes. Transmit powers provided to carry the data are allocated dynamically according to channel powers of interference and transmission, and a secondary relay is selected from considering strongest channel gain subject to increase in decoding capacity of the first data and decrease in collection time of channel state information. Closed-form outage probability expressions are derived from mathematical manipulations and verified by performing Monte Carlo simulations. An identical scheme of underlay two-way decodeand-forward relaying with random relay selection and fixed power allocations is considered to compare with the proposed SIC-SC protocol, denoted as RRS protocol. Simulation and analysis results show that the non-identical outage performances of the secondary sources in the proposed SIC-SC protocol are improved by increasing the number of the secondary relays and the interference constraint as well as decreasing the residual interference powers. Secondly, the performance of the nearer secondary source is worse than that of the farther secondary source. In addition, the proposed SIC-SC protocol outperforms the RRS comparison protocol, and effect of power allocations through channel powers is discovered. Finally, derived theory values are precise to simulation results. Keywords: Successive interference cancellation, superposition coding, power allocation, underlay cognitive radio, non-orthogonal multiple access, outage probability. 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Abstract: This paper investigates a cognitive radio network where a secondary sender assists a primarytransmitter in relaying primary information to a primary receiver and also transmits its own information toa secondary recipient. This sender is capable of jamming to protect secondary and/or primary informationagainst an eavesdropper and self-powering by harvesting radio frequency energy of primary signals.Security capability of both secondary and primary networks are analyzed in terms of secrecy outageprobability. Numerous results corroborate the proposed analysis which serves as a design guidelineto quickly assess and optimize security performance. More importantly, security capability trade-offbetween secondary and primary networks can be totally controlled with appropriate selection of systemparameters.

Abstract: Bài báo nghiên cứu ảnh hưởng tỷ lệ dung môi tới chất lượng bán thành phẩm thuốc phóng P-K59. Kết quả cho thấy, lựa chọn tỷ lệ dung môi/Pi cho quá trình trộn nitromas trong khoảng từ 130% đến 140%, hồ thuốc phóng sau khi trộn có chất lượng keo hóa tốt đảm bảo cho quá trình nén ép, độ co ngót theo đường kính kim từ 22,8% đến 25,2% và theo bề dày cháy từ 37,26% đến 39,16%. Nghiên cứu ảnh hưởng thời gian, nhiệt độ và tỷ lệ nước/thuốc phóng trong quá trình ngâm. Chế độ ngâm tối ưu: Ngâm bán thành phẩm thuốc phóng ở 45 oC, thời gian ngâm 12 giờ với tỷ lệ nước/thuốc phóng là 12, thay nước sau mỗi 01 giờ. Chế tạo được 03 mẫu thuốc phóng P-K59 trong phòng thí nghiệm với lượng chất tạo xốp và cỡ hạt chất tạo xốp khác nhau. Kết quả thử nghiệm đạn K59 cho thấy sử dụng 03 mẫu thuốc phóng P-K59 chế tạo trong phòng thí nghiệm với lượng nhồi 0,22 g cho kết quả bắn đạt yêu cầu tương đương khi sử dụng thuốc phóng cầu C-K59 của Nhà máy Z1 với lượng nhồi 0,3 g.

Abstract: The paper provides a short annotated taxonomic review of Bulbopyllum sect. Tripudianthes from the flora of Vietnam along with a species-level key for identification. The section in Vietnam includes five species, one of which is a new species for science and described under the name, B. viridipallidum. The new species was found recently from Kon Tum Province of southern Vietnam. It is similar to B. kanburiense, B. khaoyaiense, and B. wallichii, but clearly differs by having pale greenish lateral sepals and two rounded calli at the lip base fused distally into a single prominent longitudinal keel; this is inflated at the lip apex into prominent half ovoid callus. In addition, we confirm the occurrence of B. wallichii in the flora of Vietnam. The taxonomic description, data on distribution, ecology, phenology, proposed conservation status, taxonomic notes, and the comparison of the new species with morphologically similar species are reported.

Abstract: This paper presents the results of manufacturing an inhibitor layer for double-base propellant grain, with 3.5% dinitrotoluene. Curing system based on polybutylmetaacrylate and unsaturated polyester. Optimal technology parameters: curing temperature 45-50oC, curing time is 12-16 hours, diethylaniline content 0.5-1%. The post-curing material has high mechanical properties (tensile strength up to 16.2 MPa, fuel adhesion strength - flame retardant shell up to 3.8 MPa). Static and burning testing results at the Institute of Propellants and Explosives, General Department of Defence Industry meet the requirements. The research results are an important step forward in combining scientific theory and practice in manufacturing fireproof shells for ballistite fuel ingots at low temperature, supplementing existing technologies in Vietnam, and meeting the requirements of rocket industry development in the coming time.

Abstract: Mục tiêu: Đánh giá khả năng dự đoán kết quả hồi phục sau tiêu sợi huyết ở bệnh nhân (BN) đột quỵ nhồi máu não (ĐQNMN) cấp trên CT mạch não đa pha. Phương pháp nghiên cứu: Nghiên cứu hồi cứu cắt ngang trên 29 BN ĐQNMN cấp, đánh giá tuần hoàn bàng hệ trên CT mạch não đa pha và điều trị tiêu sợi huyết đường tĩnh mạch. Kết quả: Tuổi trung bình của nhóm BN nghiên cứu là 67,6 ± 11,7 năm, tỷ lệ nhóm tuổi 60 - 79 cao nhất (72,5%), tỷ lệ nhóm tuổi 〈 40 thấp nhất: 3,4%, tỷ lệ nam là 66,0%. NIHSS giảm ≥ 4 ở thời điểm 1 giờ và 24 giờ và điểm mRS ≤ 1 lúc ra viện có tuần hoàn bàng hệ mức tốt đều cao hơn so với nhóm có tuần hoàn bàng hệ trung bình lần lượt là 62,1%; 72,4% và 58,6% so với 13,7%; 13,7% và 10,3%. Diện tích dưới đường cong AUC của điểm tuần hoàn bàng hệ dự đoán khả năng hồi phục tốt ở thời điểm 1 giờ và 24 giờ sau điều trị alteplase tĩnh mạch và điểm mRS khi ra viện, đều 〈 0,6. Kết luận: Tuần hoàn bàng hệ trên CT mạch não đa pha có thể dự đoán kết quả hồi phục cho điều trị tiêu sợi huyết ở BN ĐQNMN cấp. Tuy nhiên, cần thêm các nghiêm cứu với cỡ mẫu lớn hơn.

Abstract: Aspidistra thuongiana is described and illustrated as a new species from the South Central Coast region of Vietnam. The new species has bright yellow flower and a slender pistil with a minute stigma. It is morphologically close to A. longipedunculata, but differs in shorter peduncle, bowl-shaped (vs. campanulate) perigone, shorter ovate (vs. oblong) erect to spreading (vs. recurved) perigone lobes and stamens inserted at the base (vs. middle) of perigone tube. Data on nuclear 5S-NTS region of the new species are provided, aimed to serve as a molecular characterization for comparison with its congeners.

Abstract: Abstract. Nguyen TLT, Saensouk S, Nguyen VC, Nguyen VK, Pham TTD, Nguyen DK, Nguyen DD. 2023. Taxonomic notes of Alpinia subsect. Catimbium (Zingiberaceae) in Vietnam: The first record of Alpinia nobilis and description of a new species Alpinia hoangviet. Biodiversitas 24: 5293-5301. Alpinia subsect. Catimbium is characterized by the inflorescences being a raceme, panicle or spike; bracts usually absent; prominent bracteoles, if present, almost enclosing the flower buds, calyx deeply split unilaterally, deeply concave labellum usually over 3 cm long and yellow-orange marked crimson red, reduced staminodes being subulate to lightly swollen (nearly absent), and anther usually not crested. The revision of subsect. Catimbium in Vietnam is not completed yet. We estimate that the number of this subsect. is roughly 50% of Catimbium species of the World. As a result of the examination of our living specimens collected during 2019-2022, Alpinia nobilis was defined as a new record in southern Vietnam, and Alpinia hoangviet, a new species belonging to subsect. Catimbium (Zingiberaceae: Alpinieae) from Central Vietnam is described. The taxonomic treatment with a description, photographs, distribution, ecology, conservation assessment, and morphological comparison of the new species with their allies are provided. Moreover, a revised key to all species of Alpinia subsect. Catimbium in Vietnam, is included. Alpinia hirsuta and A. latilabris were eliminated from this key. Alpinia hirsuta is considered a member of subsect. Alpinia, whereas the presence of A. latilabris in Vietnam is a misidentification.