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We investigate the influence of preliminary energy-mechanical treatment (EMT) of the initial Co–Cr–Mo-based powders in the vortex layer of ferromagnetic bodies on the structure-mechanical properties of products obtained by the spark plasma sintering (SPS). To study the properties of the powder and the sintered samples, we employed the scanning electron microscopy (SEM), the optical microscopy, the value determination of the flexural strength and the microhardness on the Vickers scale. We show that the short-time EMT of the powders (1–3 min) in the vortex layer of ferromagnetic bodies results in severe plastic deformation of the majority of the rounded particles of the original powder: they form particles of irregular shape including plates with increased surface roughness. As a result, this treatment influences positively their spark plasma sintering process and makes it possible to produce densely compact sintered material with a low-porosity structure. We discover that the sample preliminarily passing the 3-min EMT compacts densely during sintering (the relative density being 98.3%) and obtains improved mechanical properties (the microhardness and the flexural strength values being by 16% and 14%, respectively, higher than those for the sample without treatment). This improvement of structure-mechanical properties of the EMT-passed sintered samples results from intensification of the diffuse mass transfer during sintering due to the plastic deformation of the material, modification of the shape, the surface condition of the powder particles, and the increase of the total contact area between them. The increased surface roughness and the particle shape deviation from that regular lead to a decrease in the radii of curvature of their contact surfaces and thus an increase in the Laplace force magnitudes, playing the dominant role in the diffusion mass transfer during sintering.

Purpose. Study of the main characteristics of synthesizing processes of magnetite and iron nanopowders by hydrogen reduction from hydroxide compound (α-FeOOH). Materials and methods. α-FeOOH hydroxide nanopowder was obtained by chemical precipitation from aqueous solutions of iron (III) nitrate Fe(NO3)3 (10 wt. %) and alkali NaOH (10 wt. %) at room temperature, pH = 11, under the condition of continuous stirring. Synthesizing processes of Fe3O4 and Fe nanopowders by hydrogen reduction of hydroxide α-FeOOH were carried out in a tubular furnace "SNOL 0.2/1250". The study of the crystal structure as well as the composition of the powder samples was performed by X-ray phase analysis. The size and morphology of nanopowder particles were investigated by scanning and transmission electron microscopes. The specific surface area of the powders was measured by using BET method by low-temperature nitrogen adsorption. The average size of the powders articles was determined via the measured value of specific surface area. Results. It has been established that the optimal temperatures corresponding to the values of the maximum specific rate for carrying out the synthesizing processes of Fe3O4 and Fe nanopowders by hydrogen reduction are 340 and 500 °C, respectively. The resulting products are nanopowders of pure Fe3O4 and Fe after being through hydrogen reduction process for 2 hours. It was shown that Fe3O4 nanoparticles consist of particles with indefinite shape, which are prone to the formation of flakes. They have a nanometer size (about tens of nm) and are in a sintered state with connections to several neighboring particles by isthmuses. Fe nanoparticles are mainly rounded and spherical, up to one hundred nm in size and distributed separately. Originality. For the first time, the optimal temperatures have been established for synthesizing processes of Fe3O4 and Fe nanopowders by hydrogen reduction from hydroxide compound. Practical value. The research results will serve as a basis for the synthesis of nanopowders based on Fe3O4 and Fe, guarantee the acceleration of processes, ensure the necessary properties of nanopowders and can be used for various fields of science, technology, ecology and oth., Цель работы − исследование основных характеристик процессов получения нанопорошков магнетита и железа водородным восстановлением гидроксидного соединения (α-FeOOН). Материалы и методика. Нанопорошок гидроксида α-FeOOН получен химическим осаждением из водных растворов нитрата железа (III) Fe(NO3)3 (мас. доля, 10 %) и щелочи NaOH (мас. доля, 10 %) при комнатной температуре, рН = 11, в условиях непрерывного перемешивания. Процессы получения нанопорошков Fe3O4 и Fe водородным восстановлением гидроксида α-FeOOН проведены в трубчатой печи «SNOL 0,2/1250». Кристаллическую структуру и состав порошковых образцов изучали методом рентгенофазового анализа. Размер и морфологию частиц нанопорошков изучали сканирующим и просвечивающим электронно-микроскопическими методами. Удельную поверхность образцов измеряли методом БЭТ по низкотемпературной адсорбции азота. Средний размер частиц порошков определяли по данным измерения величины удельной поверхности. Результаты. Установлено, что оптимальные температуры, соответствующие значениям максимальной удельной скорости для проведения процессов получения нанопорошков Fe3O4 и Fe водородным восстановлением, равны 340 и 500 °С соответственно. Полученные продукты представляют собой нанопорошки чистых Fe3O4 и Fe при восстановлении после двух часов выдержки. Показано, что наночастицы Fe3O4 состоят из частиц неопределенной формы, которые склонны к образованию хлопьев, они имеют нанометровый размер (порядка десятков нм) и находятся в спеченном состоянии, каждая из них соединена с несколькими соседними частицами перешейками. Наночастицы Fe главным образом имеют округлую и сферическую форму; их размер составляет до 100 нм и они распределяются раздельно. Научная новизна. Впервые установлены оптимальные температуры для проведения процессов получения нанопорошков Fe3O4 и Fe водородным восстановлением гидроксидного соединения. Практическая значимость. Полученные результаты исследований послужат основой для синтеза нанопорошков на основе Fe3O4 и Fe, гарантируют ускорение процессов, обеспечение необходимых свойств нанопорошков и могут использоваться в различных областях науки, техники, экологии и др., Мета роботи − дослідження основних характеристик процесів отримання нанопорошків магнетиту і заліза водневим відновленням гідроксидної сполуки (α-FeOOН). Матеріали і методика. Нанопорошок гідроксиду α-FeOOН отриманий хімічним осадженням із водних розчинів нітрату заліза (III) Fe(NO3)3 (10 мас. %) і лугу NaOH (10 мас. %) за кімнатної температури, рН = 11, в умовах безперервного перемішування. Процеси отримання нанопорошків Fe3O4 і Fe водневим відновленням гідроксиду α-FeOOН проведені в трубчастій печі «SNOL 0,2/1250». Кристалічну структуру і склад порошкових зразків вивчали методом рентгенофазового аналізу. Розміри і морфологію частинок нанопорошків − сканувальним і просвічувальним електронномікроскопічними методами. Питому поверхню зразків вимірювали методом БЕТ за низькотемпературною адсорбцією азоту. Середній розмір частинок порошків визначали за даними вимірювання величини питомої поверхні. Результат. Установлено, що оптимальні температури, які відповідають значенням максимальної питомої швидкості для проведення процесів отримання нанопорошків Fe3O4 та Fe водневим відновленням, дорівнюють 340 та 500 °С відповідно. Отримані продукти являють собою нанопорошки чистих Fe3O4 та Fe при відновленні після двох годин витримки. Показано, що наночастинки Fe3O4 складаються з частинок невизначеної форми, які схильні до утворення пластівців, вони мають нанометровий розмір (порядку десятків нм) і перебувають у спеченому стані, кожна з них з'єднана з декількома сусідніми частинками перешийками. Наночастинки Fe, головним чином, мають округлу і сферичну форму; їх розмір складає до 100 нм і вони розподіляються роздільно. Наукова новизна. Вперше встановлено оптимальні температури для проведення процесів отримання нанопорошків Fe3O4 та Fe водневим відновленням гідроксидної сполуки. Практична значимість. Отримані результати досліджень слугуватимуть ля синтезу нанопорошків на основі Fe3O4 і Fe, гарантують прискорення процесів, забезпечення необхідних властивостей нанопорошків, і можуть використовуватися в різних галузях науки, техніки, екології тощо.

В данной работе представлены данные по изучению процессов измельчения графитовой смеси с применением разных технологий обработки в аппаратах вихревого слоя и планетарной мельнице. Исследования проводились с использованием методов лазерного анализа распределения частиц по размерам, сканирующей электронной микроскопии и рентгенофазового анализа. Установлено, что обработка в планетарной мельнице Pulverisette 7 в течение 60 мин приводит к получению полидисперсных частиц графитовой смеси, характеризующихся широким бимодальным распределением по размерам с ярко выраженными пиками максимумов в 12 и 24 мкм соответственно. Показано, что обработка графитовой смеси в аппаратах вихревого слоя АВС-80 и УАП-3 за 10 мин позволяет получить узкодисперсные частицы графита с максимумами распределения 13 и 11 мкм соответственно, что говорит о преимуществе и эффективности данной технологии по сравнению со случаем измельчения графитовой смеси в планетарной мельнице., This paper presents data on the study of grinding processes of a graphite mixture using various processing technologies in vortex layer devices and planetary mills. The studies were carried out using methods of laser analysis of particle size distribution, scanning electron microscopy and X-ray phase analysis. Processing the graphite mixture in a Pulverisette 7 planetary mill for 60 min was found to lead to the formation of polydisperse graphite particles characterized by a wide bimodal size distribution with pronounced maxima at 12 and 24 μm, respectively. We showed that processing the graphite mixture in the devices of vortex layer AVS-80 and UAP-3 in 10 min makes it possible to obtain finely dispersed graphite particles with maxima of the size distribution at 13 and 11 μm respectively, which indicates the advantage and efficiency of this technology as compared to the case of grinding the graphite mixture in the planetary mill.

Статья содержит сведения о 33 новых и редких видах рода Hoya, полученные в ходе полевых работ, проводившихся на протяжении 2012–2017 гг. в восточном Индокитае, включающем территорию Камбоджи, Лаоса и Вьетнама. Полученные результаты включают иллюстрированные описания 3 видов, новых для науки, а также 24 видов, новых для флор изучаемых стран. С учетом этих данных флора восточного Индокитая насчитывает как минимум 45 видов рода, произрастание восьми из которых задокументировано для Камбоджи, 21 – для Лаоса и 40 – для Вьетнама. Два новых для науки вида описаны из Вьетнама (H. crassipetiolataи H. nutans) и один – из Лаоса (H. uniflora). 18 видов впервые указываются для флоры Вьетнама (H. arnottiana, H. burmanica, H. chinghungensis, H. erythrina, H. erythrostemma, H. fungii, H. griffithii, H. hainanensis, H. lanceolata, H. linearis, H. loyceandrewsiana, H. mengtzeensis, H. nummularioides, H. pachyclada, H. pandurata, H. parviflora, H. revolubilis, H. vaccinioides), 9 – для флоры Лаоса (H. arnottiana, H. carnosa, H. chinghungensis, H. fungii, H. globulosa, H. griffithii, H. linearis, H. pandurata, H. polyneura) и 2 – для флоры Камбоджи (H. lobbii, H. multiflora). Выявлены новые местонахождения ряда редких видов (H. bonii, H. lockii, H. lyi, H. micrantha, H. multiflora, H. oblongacutifolia и H. verticillata), известных ранее в восточном Индокитае по единичным сборам. Для 8 видов (H. arnottiana, Hgriffithii, H. lanceolata, H. lobbii, H. nummularioides, H. oblongacutifolia, H. pachycladaи H. vaccinioides) выбраны лектотипы. Названия 5 таксонов, принимаемых ранее в качестве самостоятельных видов (H. villosa, H. pseudovalifolia, H. graveolens, H. balansae), сведены в синонимы к следующим принятым ныне видам: H. globulosa, H. micrantha, H. oblongacutifolia, H. verticillata, соответственно., This paper provides new data on 33 new or rare species of Hoya obtained in fieldwork mainly during 2012–2017 in eastern Indochina including Cambodia, Laos and Vietnam. These data include illustrated descriptions of three species new for science, as well as illustrated records of 24 species new for the floras of the studied countries. When these new data are included, the flora of eastern Indochina comprises at least 45 species. Among them eight species are recorded and documented for Cambodia, 21 sp. for Laos and 40 sp. for Vietnam; two new species are described in Vietnam (H. crassipetiolata and H. nutans) and one species is described from Laos (H. uniflora). Eighteen species were recorded newly for the flora of Vietnam (H. arnottiana, H. burmanica, H. chinghungensis, H. erythrina, H. erythrostemma, H. fungii, H. griffithii, H. hainanensis, H. lanceolata, H. linearis, H. loyceandrewsiana, H. mengtzeensis, H. nummularioides, H. pachyclada, H. pandurata, H. parviflora, H. revolubilis, H. vaccinioides), nine for Laos (H. arnottiana, H. carnosa, H. chinghungensis, H. fungii, H. globulosa, H. griffithii, H. linearis, H. pandurata, H. polyneura) and two for Cambodia (H. lobbii, H. multiflora). New localities were discovered for H. bonii, H. lockii, H. lyi, H. micrantha, H. multiflora, H. oblongacutifolia, and H. verticillata known earlier in Cambodia, Laos and Vietnam by few collections. Lectotypes are proposed for the following eight species: H. arnottiana, H griffithii, H. lanceolata, H. lobbii, H. nummularioides, H. oblongacutifolia, H. pachyclada, and H. vaccinioides. Names of five taxa earlier known as separate species (H. villosa, H. pseudovalifolia, H. graveolens, H. balansae) are regarded as synonyms of H. globulosa, H. micrantha, H. oblongacutifolia, H. verticillata respectively.

Michelia citrata is one of threatened species in Vietnam. It grows in subtropical evergreen broadleaved and coniferous forests at elevations higher than 1000m in Ha Giang province. In Cao Ta Tung forest, Quan Ba district, Ha Giang province, the distribution of 33 individuals of Michelia citrata is scattered with low regeneration rate and mature trees threatened by firewood and planting Cardamom. Keywords Magnoliaceae, Michelia citrata, Ha Giang, Vietnam References [1]. Malin Rivers, Emily Beech, Lydia Murphy and Sara Oldfield, The Red list of Magnoliaceae, revised and extended, BGCI, Richmond, UK, 2016.[2]. Vu Quang Nam, Taxonomic Revision of the Family Magnoliaceae from Vietnam, Thesis of Doctorate, Graduate University of The Chinese Academy of Sciences. Guangzhou, 2011.[3]. Từ Bảo Ngân, Nghiên cứu sự phân bố, sinh thái, sinh học và hiện trạng bảo tồn của loài Giổi chanh (Michelia citrata (Noot. & Chalermglin) Q. N. Vu & N. H. Xia) tại xã Tùng Vài, huyện Quản Bạ, tỉnh Hà Giang, Luận văn Thạc sĩ, Trường Đại học Khoa học Tự nhiên, ĐHQGHN, 2014.[4]. Chalermglin P. and H. P. Nooteboom, A new species of and a new combination in Magnolia (Magnoliaceae), Blumea, 52, 2007: 559-562.[5]. Nguyễn Quang Hiếu, Nguyễn Tiến Hiệp, Từ Bảo Ngân, Nguyễn Sinh Khang, Kết quả nghiên cứu bước đầu về thành phần loài thuộc họ Ngọc lan (Magnoliaceae Juss.) tại tỉnh Hà Giang và đánh giá tình trạng bảo tồn của chúng, Hội nghị Khoa học toàn quốc lần thứ sáu về Sinh thái và Tài nguyên sinh vật, Viện Sinh thái và Tài nguyên sinh vật, Hà Nội, 2015: 130-136.[6]. Vũ Quang Nam, Xia Nianhe, Bổ sung loài Michelia citrata (Noot. & Chalermglin) Q. N. Vu & N. H. Xia (họ Mộc lan - Magnoliaceae Juss.) cho hệ thực vật Việt Nam, Tạp chí sinh học, 33(4), 2011: 42-44.[7]. Nooteboom H. P. and P. Chalermglin, The Magnoliaceae of Thailand, Thai For. Bull. (Bot.). 37, 2009, 121.[8]. Nguyễn Nghĩa Thìn, Các phương pháp nghiên cứu thực vật, NXB Đại học Quốc gia Hà Nội, Hà Nội, 2007.[9]. UBND tỉnh Hà Giang, Báo cáo tổng hợp Quy hoạch bảo tồn Đa dạng sinh học tỉnh Hà Giang đến năm 2020, định hướng đến năm 2030” kèm theo QĐ số 1589/QĐ-UBND ngày 27/8/2015 của UBND tỉnh Hà Giang về việc Phê duyệt Quy hoạch bảo tồn Đa dạng sinh học tỉnh Hà Giang đến năm 2020, định hướng đến năm 2030, 2015.

Whether natural product drug discovery programs should rely on wild plants collected "randomly" from the natural environment, or whether they should also include plants collected on the basis of use in traditional medicine remains an open question.This study analyzes whether plants with ethnomedical uses from Vietnam and Laos have a higher hit rate in bioassay testing than plants collected from a national park in Vietnam with the goal of maximizing taxonomic diversity ("random" collection).All plants were extracted and subjected to bioassay in the same laboratories. Results of assays of plant collections and plant parts (samples) were scored as active or inactive based on whether any extracts had a positive result in a bioassay. Contingency tables were analyzed using χ(2) statistics.Random collections had a higher hit rate than ethnomedical collections, but for samples, ethnomedical plants were more likely to be active. Ethnomedical collections and samples had higher hit rates for tuberculosis, while samples, but not collections, had a higher hit rate for malaria. Little evidence was found to support an advantage for ethnomedical plants in HIV, chemoprevention and cancer bioassays. Plants whose ethnomedical uses directly correlated to a bioassay did not have a significantly higher hit rate than random plants.Plants with ethnomedical uses generally had a higher rate of activity in some drug discovery bioassays, but the assays did not directly confirm specific uses.Ethnomedical uses may contribute to a higher rate of activity in drug discovery screening.

Taxonomic review of the genus Calocedrus in Vietnam accompanied with modern available data on distribution, ecology and habitat conditions of its two aboriginal species is presented. Detailed illustrated description of recently discovered species C. rupestris endemic to rocky limestone mountains of northern Vietnam is provided. This rare species differs from wide-spread C. macrolepis in obtuse to broadly-obtuse leaf apex; small, subsessile, 4-scaled, broadly-ovate seed cones 4-5(6) x 2.5-3(3.5) mm with very short stalk 0.5-1(1.5) mm long, having 6-8(12) obtuse scales, and fertile seed scales with incurved rounded apex having rough, more or less flat surface without any mucro. Trees of C. rupestris were found as a co-dominant in relictual coniferous forests on rocky hills and ridges composed of highly eroded limestone. Relictual primary, highly endangered woods with this rare tree, as well as their floristic complex represent a unique plant diversity center of global significance. Urgent and effective protection of these areas should be of highest priority for nature conservation activity.

Trevesia vietnamensis J. Wen & P.K. L?c (Araliaceae) is described as an unusual new species from northwestern Vietnam. This species has 4?5-merous flowers with a 4-5-locular ovary and palmately compound leaves and would thus fit well within Brassaiopsis morphologically. Phylogenetic analysis using the nuclear ribosomal ITS and the chloroplast ndhF and trnL-F sequences, however, clearly places the new taxon in Trevesia, defined to include species with 6-16-merous flowers with 6-16-locular ovaries, and palmately lobed simple leaves. The discovery of Trevesia vietnamensis thus blurs the generic boundary between Trevesia and Brassaiopsis. The phylogenetic analysis suggests a sister-species relationship between Trevesia vietnamensis and T. lateospina from northern Thailand, a finding supported by a shared morphological character?the presence of setose hairs on the inflorescences and young stems. Trevesia vietnamensis is restricted to two localities in northwestern Vietnam. It grows in limestone areas in valleys and on shady mountain slopes at 500-700 m in primary, tropical, monsoon, broad-leaved forests.

The Convention on Biodiversity mandates a new approach to the discovery of natural product drugs, one that incorporates concepts of national ownership of genetic resources, intellectual property rights in traditional knowledge, and sharing of economic benefits with countries that are the source of new natural products. The International Cooperative Biodiversity Group (ICBG) program was established to support experimentation in implementation of the Convention through development and execution of international agreements for bioprospecting. The agreement of one such ICBG program, between the University of Illinois at Chicago and institutions in Vietnam and Laos, is presented here. The core elements contained in the single, five-way Memorandum of Agreement are the arrangements for intellectual property rights, treatment of informed consent, and plans for benefit-sharing (including the sharing of short- and long-term royalty benefits, capacity building, and community reciprocity). Program participants were able to develop a practical and flexible agreement that satisfies the wishes of all institutions that are parties to it.

The phylogenetic position of the recently described monotypic Vietnamese genus Grushvitzkya is evaluated using nuclear ribosomal ITS and chloroplast ndhF sequence data. Grushvitzkya stellata has often been considered as intermediate between Brassaiopsis and Trevesia, but differs in having a 5-locular ovary rather than a 2- or 6–16-locular ovary, respectively. The molecular data indicate that Grushvitzkya is deeply nested within Brassaiopsis and has a close relationship with B. phanrangensis from central and southern Indochina, and B. stellata from the regions bordering China and Vietnam. The Kimura 2-parameter distances of the ITS sequences between G. stellata and B. phanrangensis and B. stellata are 0.403 and 0.945%, respectively. Furthermore, G. stellata and B. phanrangensis have an identical ndhF sequence profile. Grushvitzkya stellata differs from B. stellata by a single nucleotide in their ndhF sequences. The available evidence is compatible with the hypothesis that Grushvitzkya diverged recently from B. phanrangensis and B. stellata. Although these three closely related species all possess stellate trichomes, G. stellata and B. phanrangensis have highly similar trichome micromorphology, with almost no difference in size, shape and branching pattern, supporting a very close relationship between the two taxa. The higher number of locules in the ovary of Grushvitzkya appears to be a secondary increase despite earlier interpretations that higher numbers are evolutionarily primitive. Grushvitzkya is herein merged with Brassaiopsis; because the combination B. stellata is occupied, a new name, Brassaiopsis grushvitzkyi, is proposed. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 142, 455–463.

Pinus dalatensis Ferre’(Family: Pinaceae) is an endemic plant with restricted habitats at higher altitudes in Vietnam highland. The species are now near threatened by over-exploitation and habitat destruction. The genetic variation within and among populations of P. dalatensis was investigated by 41 microsatellite (single sequence repeat, SSR) primers, but only 11 SSR primers showed polymorphism bands. In all, 70 sampled trees from six populations in Vietnam highland were analyzed in this study, samples were collected from populations located in different altitude. A total of 40 allelic variants have been detected. The mean number of alleles per locus was 2.197. The SSR data showed a genetic diversity parameters within populations with an average of I = 0.524, Ho = 0.222, He = 0.317, Fis =0.333 and Ap = 0.106. The number private alleles (Ap) was only found in four populations, the Hoa Son population showed the highest (0.273), followed by Da Chay (0.182), and value of 0.091 for all Ngoc Linh and A Yun. Analysis of molecular variance analysis showed that most genetic variation was within populations of 57.504 % and among population of 42.496 %. The population pairwise differentiations indicated that most of the populations were significantly differentiated p < 0.001 with Fst values ranged from 0.195 to 0.418. This study highlights the importance of conserving the genetic resources of P. dalatensis species

The impact of the University of Illinois at Chicago-based Vietnam-Laos International Cooperative Biodiversity Group (ICBG) Program "Studies on Biodiversity of Vietnam and Laos", which has been in operation for the period of 1998-2005, touches on five major areas of endeavor: (a) biodiversity inventory and conservation; (b) studies on medicinal plants; (c) drug discovery and development; (d) economic development; and (e) issues on intellectual property rights and benefit sharing in natural products drug discovery and development. Highlights are presented and the significance is discussed.