The kinetic features of coating growth on titanium alloy Ti–6A1–4V by plasma electrolytic oxidation (PEO) are investigated. It was observed that the coating growth rate decreases significantly with the increasing of the PEO time treatment. At the same time, large longitudinal pores (cracks) were formed; thus, the major part of the coating is separated from the substrate. Coating growth is realized by the two mechanisms: (a) migration-diffusional and (b) thermochemical treatment of the deposited aluminum hydroxide (electrolysis) and oxidation of the substrate at the bottom of the coating pores. It presumably occurs due to the saturation of the electrolyte in the pores with titanium hydroxide and the relatively low intensity of the microdischarges, which is insufficient to eject the substance from the channels for ‘pancake’ formation. This increases the amount of the aluminum titanate (TiAl2O5) in the coating. The latter presumably forms due to a eutectic reaction in the coating or due to the exothermic reactions of titanium dioxide formation. The TiAl2O5-based coating containing at least 10% aluminum oxide α-Al2O3 (more than 20% in the outer layer) and 11% titanium dioxide (TiO2) increases the wear resistance of the titanium alloy at least six times.
Panax L. is a small genus in the Araliaceae family. In Vietnam, this genus is distributed in the high mountains in the North and in some high mountains in the Central Highlands. In traditional medicine, roots and rhizomes of all Panax species are of high utility. Recently, the finding of new distributions of some Panax species in Vietnam has caused much controversy and confusion. This study investigates 27 fresh specimens of 6 taxa of Panax genus that have been collected from 6 provinces of Vietnam. Based on the combined ITS-rDNA and matK dataset, a well-resolved phylogeny of Panax species/varieties distributed in Vietnam was constructed. Thereby, the study suggests identifying Tam that la xe as Panax stipuleanatus H.T.Tsai et K.M.Feng and Sam puxailaileng as Panax vietnamensis var. fuscidiscus K.Komatsu, S.Zhu & S.Q.Cai, which contributes a new distribution point of this variety in Vietnam. The study also shows that ITS-rDNA and matK genes are highly potential in identifying and distinguishing the taxa of Panax genus. Keywords Panax, ginseng, molecular phylogeny, taxonomy, ITS-rDNA, matK. References [1] Xiang, Q.B. & Lowry, P.P. Araliaceae, In: Wu, C.Y., Rawen, P.H. & Hong (2007).[2] Nguyen Tap, The species of Panax L. in Vietnam, Journal of Medicinal Material, 10 (3) (2005) 71-76 (in Vietnamese).[3] Phan Ke Long, Le Thanh Son, Phan Ke Loc, Vu Dinh Duy and Pham Van The, Lai Chau ginseng Panax vietnamensis var. fuscidiscus K. Komatsu, S. Zhu & S.Q. Cai.I. morphology, ecology, distribution and conservation status, Proceedings of the 2nd VAST – KAST workshop on biodiversity and bio-active compounds, Hanoi- Vietnam, October 28th – 29th (2013), pp. 65-73, Publishing house for science and technology. [4] Nong Van Duy, Le Ngoc Trieu, Nguyen Duy Chinh & Van Tien Tran, A new variety of Panax (Araliace) from Lam Vien Plateau, Vietnam and its molecular evidence, J. Phytotaxa 277(1) (2016) 047-058. http://dx.doi.org/10. 11646/ phytotaxa.277.1.4[5] Tran Ngoc Lan et al., Results of study on Sam Puxailaileng in high moutain, Nghe An province, Nghe An journal of Science and Technology 12 (2016) 7-11 (in Vietnamese). [6] Do Huy Bich et al., Medicinal plant and animal in Vietnam, ep. II (2004), Science & Technic Pub. pp. 1255 (in Vietnamese).[7] X. Chen, B. Liao, J. Song, X. Pang, J. Han, S. Chen, A fast SNP identification and analysis of intraspecific variation in the medicinal Panax species based on DNA barcoding, Gene 530(1) (2013) 39-43. http://doi.org/10.1186/j.gene.2013.07.097[8] Jun Wen and Elizabeth A. Zimmer, Phylogeny and Biogeography of Panax L. (the Ginseng Genus, Araliaceae): Inferences from ITS Sequences of Nuclear Ribosomal DNA, Molecular Phylogenetics and Evolution 6(2) (1996) 167-177.[9] C. Lee, J. Wen, Phylogeny of Panax using chloroplast trnC–trnD intergenic region and the utility of trnC–trnD in interspecific studies of plants, Mol Phylogenet Evol 31(2004): 894-903, DOI: 10.1016/j.ympev.2003.10.009[10] Y. Zuo, Z. Chen, K. Kondo, T. Funamoto, J. Wen, S. Zhou, DNA barcoding of Panax species, Planta Med. 2011 Jan, 77(2) (2011):182-187. Doi: 0.1055/s-0030-1250166.[11] K. Komatsu, S. Zhu, S.Q. Cai, A new variety of the genus Panax from Southern Yunnan, China and its nucleotide sequences of 18S ribosomal RNA gene and matK gene, J. Jap. Bot 78(2) (2003) 86-94. [12] V. Manzanilla1, A. Kool, L. Nguyen Nhat, H. Nong Van, H. Le Thi Thu and H. J. de Boe, Phylogenomics and barcoding of Panax: toward the identification of ginseng species. BMC Evolutionary Biology (2018) 18-44. http://doi.org/10.1186/s12862-018-1160-y[13] Vu Huyen Trang, Hoang Dang Hieu, Chu Hoang Ha, Study on DNA barcode for identify Sam ngoc linh, National conference of biotechnology, Ep.2, (2013) 1100-1104.[14] Nguyen Thi Phuong Trang, Nguyen Thi Hong Mai, Zhuravlev Yury N, Reunova Galina D., rbcL and rpoB gene sequences of Panax vietnamensis var. fuscidiscus and Panax vietnamensis, the background for identification and comparison, Journal of Biology 39(1) (2016) 80-85. http://doi.org/10.15625/0866-7160/v39n1.7870[15] Phan Ke Long, Tran Thi Viet Thanh, Nguyen Thien Tao, Phan Ke Loc, Nguyen Tu Lenh, Nguyen Tien Lam, Dang Xuan Minh, Morphological and molecular characsteristics of Panax sp. (Araliaceae) from Phu Xai Lai Leng mountain, Nghe An province, Vietnam, Journal of Biology 36(4) (2014) 494-499. https://doi.org/ 10.15625/0866-7160/v36n4.5212[16] Phan Ke Long, Vu Dinh Duy, Phan Ke Loc, Nguyen Giang Son, Nguyen Thi Phuong Trang, Le Thi Mai Linh, Le Thanh Son, Phylogenetic relationships of the Panax samples collected in Lai Chau province based on matK and ITS-rDNA sequences, Journal of Biology 12(2) (2014) 327-337 (in Vietnamese).[17] Nguyen Thi Phuong Trang, Le Thanh Son, Nguyen Giang Son, Phan Ke Long, A new ginseng species Panax sp. (Araliaceae) in Vietnam, Journal of Pharmacology 10 (2011) 59-63. [18] Pham Thi Ngoc, Pham Thanh Huyen, Nguyen Quynh Nga, Nguyen Minh Khoi, Morphological characteristics of genus Panax L. (Araliaceae) in Vietnam, Journal of Medicinal Materials, 22(3) (2017) 315-322.
The genus Uvaria Juss. is distinguished other genus of Annonaceae especially: Stellate or caespitose hairs, flowers bisexual opposite to leaves, flower are solitary or cymose. Sepal 3, valvate,… Uvaria clementis (Merr.) Attan., I.M. Turn&R.M.K Saunders distributed from Malaysia, Indonesia, Brunei to Thailan, Campuchia,… The specimen which collected at Dongnai province and saved at The Hebarium National Instiute of Medicinal Materialis is newly recorded for the flora of Vietnam. This study, we are described, illustrated and notes on taxonomy of Uvaria clementis Teaching and scientific research are two main.
Paris L. is a small genus distributed widely in Eurasia. In Vietnam Paris occur in evergreen broad-leaved forests in some mountainous areas of the North and the Central highlands. Due to over-exploitation as well as habitat loss, populations of some Paris species are seriously declining. This genus has not been studied extensively in Vietnam. The aim of this study was to define the morphological characteristics of the genus Paris in Vietnam. Morphological description, dichotomous key for identification, ecology and distributions of the genus in Vietnam are reported. The results show that this genus in Vietnam comprises 8 species and 2 varieties, possesing unilocular ovary with parietal placenta.
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