Double-Side Electromagnetic Band Gap Structure for Improving Dual-Band MIMO Antenna Performance

A double-side EBG structure with equivalent circuit model is proposed in this paper. Making H shape on surface and H with bridge shape on ground, the novel EBG that is built on FR4 substrate with height of 1.6mm, gets compact size of 8.6x8.6 mm2 at 2.6 GHz resonant frequency. Using 1x7 EBG structures for dual-band MIMO system, several performance parameters of antenna are improved. Firstly, the mutual coupling between antenna elements gets -40dB in the lower band and -30dB in the higher one with narrow distance of 0.11l from feeding point to feeding point. Then, at 2.6GHz, the antenna gain is increased significant by 160% as well as radiation efficiency of antenna is better. This improvement is unable to get in previous EBG studie

Theoretical predictions of melting behaviors of hcp iron up to 4000 GPa

The high-pressure melting diagram of iron is a vital ingredient for the geodynamic modeling of planetary interiors. Nonetheless, available data for molten iron show an alarming discrepancy. Herein, we propose an efficient one-phase approach to capture the solid-liquid transition of iron under extreme conditions. Our basic idea is to extend the statistical moment method to determine the density of iron in the TPa region. On that basis, we adapt the work-heat equivalence principle to appropriately link equation-of-state parameters with melting properties. This strategy allows explaining cutting-edge experimental and ab initio results without massive computational workloads. Our theoretical calculations would be helpful to constrain the chemical composition, internal dynamics, and thermal evolution of the Earth and super-Earths

ĐA DẠNG DI TRUYỀN QUẦN THỂ CÁ CHÌNH HOA (Anguilla marmorata) TẠI QUẢNG TRỊ

This study was conducted to evaluate the population genetic diversity of the wild Anguilla marmorata in Quang Tri province by comparing the DNA sequences of the mitochondrial control region (CR) gene with those of other giant mottled eel populations in the world. The results indicate that the genetic distance between individuals in the Quang Tri population ranged from 0 to 0.261, with an average of 0.024. Among 31 individuals, there were 203 distinct polymorphism sites (S), which led to 209 mutation sites (Eta) and 31 different haplotypes. The average number of distinct nucleotides (k) was 29,299. The nucleotide diversity factor (Pi) accounted for 26.09 × 10–3, and the minimum number of recombination processes (Rm) in the population was 51 events. The majority of eel samples collected at the site had close genetic relationships with those of the North Pacific population (27/31 individuals), and four eel samples had close genetic relationships with those of the South Pacific population. The finding of the four giant mottled eels in Quang Tri belonging to the South Pacific population is considered a significant result of this study.Nghiên cứu này được thực hiện nhằm đánh giá đa dạng di truyền của quần thể cá Chình hoa (Anguilla marmorata) tự nhiên tại tỉnh Quảng Trị dựa trên việc so sánh trình tự DNA của vùng gene điều khiển CR (control region) ty thể với các quần thể cá Chình hoa trên thế giới. Kết quả cho thấy khoảng cách di truyền giữa các cá thể trong quần thể dao động từ 0 đến 0,261, đạt trung bình 0,024. Trong 31 cá thể, 203 vị trí đa hình tách biệt (S) đã tạo ra 209 vị trí đột biến (Eta) với 31 kiểu haplotype khác nhau. Số lượng các nucleotide khác biệt trung bình là 29.299 (k); hệ số đa dạng nucleotide chiếm 26,09 × 10–3 (Pi); số lượng tối thiểu để xẩy ra quá trình tái tổ hợp (Rm) trong quần thể tương ứng với 51 sự kiện. Phần lớn cá thể thu được tại Quảng Trị có quan hệ di truyền gần gũi với quần thể cá Chình hoa Bắc Thái Bình Dương (27/31 cá thể) và 4 cá thể có mối quan hệ di truyền gần gũi với quần thể Nam Thái Bình Dương. Việc phát hiện các cá thể Chình hoa tại Quảng Trị có di truyền gần gũi với các cá thể thuộc Nam Thái Bình Dương được xem như một điểm đáng chú ý trong nghiên cứu này

Online Shopping in Relationship with Perception, Attitude, and Subjective Norm during COVID-19 Outbreak: The Case of Vietnam

People all across the world, especially in Vietnam, have been motivated to make online purchases since the COVID-19 pandemic, which started in early 2020. Despite the problematic developments of the COVID-19 pandemic throughout the 2020–2021 period, Vietnam has experienced a considerable increase in e-commerce, both in terms of users and revenue, contributing considerably to national economic growth. The purpose of this study is to examine how COVID-19 affects Vietnamese customers’ online purchasing decisions. We conducted a survey of 638 Vietnamese internet shoppers for this, and the results were analyzed using SPSS. The results show that attitudes, perceived ease of use, perceived usefulness, and subjective norms all positively and significantly impact customer purchase intention. The desire to make an online purchase, however, is negatively and negligibly impacted by perceived risk. Online purchasing behavior is positively influenced by the intention to buy online. The perceived risk of the COVID-19, in particular, significantly modifies the relationship between perceived usefulness and perceived usability and online shopping intention, but only marginally modifies the relationship between attitude, subjective norms, and perceived risk and online purchase intention. Using a combined Theory of Acceptance Model (TAM) and Theory of Planned Behaviors (TPB) model with COVID-19 as an external model variable, the study adds to the body of knowledge by providing empirical findings

Online Shopping in Relationship with Perception, Attitude, and Subjective Norm during COVID-19 Outbreak: The Case of Vietnam

People all across the world, especially in Vietnam, have been motivated to make online purchases since the COVID-19 pandemic, which started in early 2020. Despite the problematic developments of the COVID-19 pandemic throughout the 2020–2021 period, Vietnam has experienced a considerable increase in e-commerce, both in terms of users and revenue, contributing considerably to national economic growth. The purpose of this study is to examine how COVID-19 affects Vietnamese customers’ online purchasing decisions. We conducted a survey of 638 Vietnamese internet shoppers for this, and the results were analyzed using SPSS. The results show that attitudes, perceived ease of use, perceived usefulness, and subjective norms all positively and significantly impact customer purchase intention. The desire to make an online purchase, however, is negatively and negligibly impacted by perceived risk. Online purchasing behavior is positively influenced by the intention to buy online. The perceived risk of the COVID-19, in particular, significantly modifies the relationship between perceived usefulness and perceived usability and online shopping intention, but only marginally modifies the relationship between attitude, subjective norms, and perceived risk and online purchase intention. Using a combined Theory of Acceptance Model (TAM) and Theory of Planned Behaviors (TPB) model with COVID-19 as an external model variable, the study adds to the body of knowledge by providing empirical findings

Study on the Thermodynamic Properties of Thin Film of FCC Interstitial Alloy AuSi at Zero Pressure Using the Statistical Moment Method

We built a model and proposed a theory about the thermodynamic properties of face-centered cubic (FCC) binary interstitial alloy’s thin films based on the statistical moment method and performed numerical calculations for AuSi (gold silicide). First, the statistical moment method (SMM) calculations for the thermodynamic properties of Au are compared with reported experiments and calculations that show a good agreement between the calculations in this paper and earlier studies. Additionally, the SMM calculations for thermodynamic properties of AuSi alloy films are performed, which show that the thermal expansion coefficient, the specific heat at constant volume, and the specific heat at constant pressure increases, while the isothermal elastic modulus decreases with increasing temperature and increasing interstitial atom concentration. Furthermore, when the number of layers reaches 100, the thermodynamic properties of the film are similar to those of the bulk material. The achieved theoretical results for AuSi films are novel and can be useful in designing future experiments

New paleomagnetic results of upper Permian - lower Triassic volcanic sequences from the Hoa Binh area, northwest Vietnam

Oriented-core samples (125) from twelve sites collected from the Late Permian-Early Triassic volcanic Vien Nam formation exposed at the Hoa Binh Dam area, northwest Vietnam yield interpretable magnetizations in progressive demagnetization. The characteristic remanent magnetization (ChRM) components carried by magnetite and hematite are successfully isolated from secondary components and reveal a mean, in situ (geographic coordinates) paleomagnetic direction of Decl. = 33.8o, Incl. = -28.4o (a95= 9.5o, k = 30.3, N = 9 site mean directions), corresponding to a virtual geomagnetic pole located at l = 41.1 oN, f = 239.8 oE and a paleo-latitude for the study area situated at ~15 oS during the Late Permian to Early Triassic. A comparison of the pole we report in this study with the Late Permian-Early Triassic part of the South China Block apparent polar wander path shows that this volcanic terrane of northwest Vietnam has been close to if not a coherent part of the South China Block since the Late Permian.  This result implies that insignificant cumulative displacement has occurred along the Ailao Shan/Red River fault system during the Cenozoic India-Eurasia collision.References Achache, J., Courtillot, V., 1985: A preliminary Upper Triassic paleomagnetic pole for the Khorat Plateau (Thailand): Consequences for the accretion of Indochina against Eurasia.Earth Planet. Sci. Lett., 73, 147-157. Cai, J.-X., Zhang, K.J., 2009: A new model for the Indochina and South China collision during the Late Permian to the Middle Triassic. Tectonophysics 467, 35-43. Chan, L.S., Wang, C.Y., Wu, X.Y., 1984: Paleomagnetic results from some Permian-Triassic rocks from southwestern China. Geophys. Res. Lett., 11, 11, 1157-1160. Chen, Y., Courtillot, V., 1989: Widespread Cenozoic (?) remagnetization in Thailand and its implications for India-Asia collision. Earth Planet. Sci. Lett., 93, 113-122. CungThuong Chi, 1996: Paleomagnetism of Mesozoic and Cenozoic rocks from Vietnam: Implications for the Tertiary tectonic history of Indochina and a test of the extrusion model. Ph.D. Dissertation, 228pp., Texas AM University, College Station, Texas, USA. Cung Thuong Chi, Nguyen Quoc Cuong, Nguyen Trong Yem, 2000a: Preliminary paleomagnetic results of Late Permian-Early Triassic basalts from northwestern Vietnam and their tectonic implications. Journal of Geology, A/259, 7-8/2000, 1-8. (In Vietnamese). Cung Thuong Chi, Nguyen Trong Yem, Nguyen Quoc Cuong, 2000b: Paleomagnetic study on Late Jurassic-Cretaceous extrusive and intrusive rocks from northwestern Vietnam. Journal of Geology, A/256, 1-2/2000, 1-8. (In Vietnamese). Dercourt, J., Ricou, L.E., Vrielynck, B. (Eds.), 1993 : Atlas Tethys Palaeoenvironmental Maps Gauthier-Villars, Paris 307pp., 14 maps, 1 plate. Enkin, R.J., 1990: Formation et deformation de l’Asie depuis la fin de l’ere primaire: les apports de l’etudepaleomagnetique des formations secondaires de Chine du Sud. Ph.D. Thesis, 333 pp., Univ. de Paris 7. Enkin, R.J., Yang, Z., Chen, Y., Courtillot, V., 1992b: Paleomagnetic constraints on the geodynamic history of the major blocks of China from the Permian to the present. J. Geophys. Res., 97, B10, 13,953-13,989. Fang, W., Van Der Voo, R., 1990: Paleomagnetism of the Late Permian Emeishan basalt, Yunnan, China. Eos Trans. AGU, 71, 488. Fisher, R.A., 1953: Dispersion on a sphere. Proc. Roy. Soc. London, Series A, 217, 295-305. Gatinsky, Y.G., Hutchinson, C.S., 1986: Cathaysia, Gondwanaland and the Palaeotethys in the evolution of continental Southeast Asia. Proceed. GeoSea V Congress, Geol. Soc. Malaysia Bull., 20. Glotov, A.I., Polyakov, G.V., Hoa, T.T., Balykin, P.A., Akimtsev, V.A., Krivenko, A.P., Tolstykh, N.D., Phuong, N.T., Thanh, H.H., Hung, T.Q., Petrova, T.E., 2001: The Ban Phuc Ni-Cu-PGE deposit related to the Phanerozoic komatiite-basalt association in the Song Da rift, northwestern Vietnam. Can. Mineral.39, 573-589. Hanski, E., Walker, R.J., Huhma, H., Polyakov, G.V., Balykin, P.A., Tran, Trong Hoa, Ngo, Thi Phuong, 2004: Origin of the Permian-Triassic komatiites, northwestern Vietnam. Contributions to Mineralogy and Petrology 147, 453-469. Heller, F., Lowrie, W., Li, H., Wang, J., 1988: Magnetostratigraphy of the Permo-Triassic boundary section at Shangsi (Guanggyuan, Sichuan, China). Earth Planet. Sci. Lett., 88, 348-356. Huang, K., Opdyke, N., Kent, D., Xu, G., Tang, R., 1986: Further paleomagnetic results from the Permian Emeishan basalts in SW China (in Chinese). KexueTongbao, 31, 1192-1201. Hutchinson, C.S., 1989: The palaeo-Tethyan realm and Indosinian orogenic system of Southeast Asia. In: Sengor, A.M.C. (Ed.). Tectonic Evolution of the Tethyan Region, 585-643, Academic San Diego, California, 1989b. Kirschvink, J.L., 1980: The least-square line and plane and the analysis of paleomagnetic data. Geophys. J. R. Astron. Soc. London, 62, 699-718. Lacassin, R., Leloup, P.H., Trinh, P.T., Tapponnier, P., 1998: Unconformity of red sandstones in north Vietnam: field evidence for Indosinian orogeny in northern Indochina? Terra Nova 10, 106-111. Lepvrier, C., Maluski, H., Vu Van Tich, Leyreloup, A., Phan Truong Thi, Nguyen Van Vuong, 2004: The Early Triassic Indosinian orogeny in Vietnam (Truong Son Belt and Kontum Massif); implications for the geodynamic evolution of Indochina. Tectonophysics 393, 87-118. Lepvrier, C., Nguyen Van Vuong, Maluski, H., Phan Truong Thi, Tich Van Vu, 2008: Indosinian tectonics in Vietnam. C. R. Geoscience 340, 94-111. Li, Z.X., Powell, CMcA., 2001: An outline of the palaeogeographic evolution of the Australian region since the beginning of the Neoproterozoic. Earth Science Reviews 53, 237-277. Li, Z.X., Zhang, I., Powell, C.McA., Trench, A., 1993: Palaeozoic global reconstructions, In: Long, J.A. (Ed.). Palaeozoic Vertebrate Biostratigraphy and Biogeography. Belhaven Press, London, pp. 25-53. Lin, J.L., 1984: The apparent polar wonder paths for the North and South China blocks. Ph.D. Thesis, 248 pp. Univ. of California, Santa Barbara. Liu, C., Zhu, R., Jing, Z., 1985: Paleomagnetic study of Late Permian Emeishan basalts from Panxi and its neighbouring areas (in Chinese). In: Contributions to Panxi rift, China, Vol. 2, edited by Y. Zhang, pp. 194-200, Geological Publishing House, Beijing. McElhinny, M.W., 1981: Fragmentation of Asia in the Permian. Nature 293, 212-216. Metcalfe, I., 1988: Origin and assembly of Southeast Asia continental terranes, Gondwana and Tethys, In: Audley-Charles, M.G., Hallam, A. (Eds.). Geological Society of London Special Publication 37, 101-118. Metcalfe, I., 1991: Late Palaeozoic and Mesozoic palaeogeography of Southeast Asia. Palaeogeography, Palaeoclimatology, Palaeoecology 87, 211-221. Metcalfe, I., 1996: Pre-Cretaceous evolution of SE Asian terranes. In: Hall, R., Blundell, D. (Eds.). Tectonic Evolution of Southeast Asia. Geological Society of London Special Publication 106, 97-122. Metcalfe, I., 1998: Palaeozoic and Mesozoic geological evolution of the SE Asian region, multidisciplinary constraints and implications for biogeography. In: Hall, R., Holloway, J.D. (Eds.). Biogeography and Geological Evolution of SE Asia. Backhuys Publishers, Amsterdam, pp. 25-41. Metcalfe, I., 2002: Permian tectonic framework and palaeogeography of SE Asia. Journal of Asian Earth Sciences 20, 551- 566. Metcalfe, I., 2011: Tectonic framework and Phanerozoic evolution of Sundaland. Gondwana Research 19, 3-21. Metcalfe, I., 2012: Changhsingian (Late Permian) conodonts from Son La, northwest Vietnam and their stratigraphic and tectonic implications. Journal of Asian Earth Sciences 50, 141-149. Phan Cu Tien, 1977: Late Permian-Early Triassic sediments from northwestern Vietnam. In: The geological problems of NW Vietnam region, Science and Technique Publisher House, Hanoi, pp.109-151. (In Vietnamese). Polyakov, G.V., Tran Trong Hoa, Akimtsev, V.A., Balykin, P.A., Ngo Thi Phuong, Hoang Huu Thanh, Tran Quoc Hung, Bui An Nien, Tolstykh, N.D., Glotov, A.I., Petrova, T.E., Vu Van Van, 1999: Ore and geochemical specialization of Permo-Triassic ultramafic-mafic complexes in North Vietnam. Geologiya i Geofizika (Russian Geology and Geophysics) 40 (10), 1474-1487 (1453-1467). Sengor, A.M.C., 1979: Mid-Mesozoic closure of Permo-Triassic Tethys and its implications. Nature 279, 590-593. Sengor, A.M.C., 1984: The Cimmerideorogenic system and the tectonics of Eurasia. Geological Society of America Special Paper 195, 82. Sengor, A.M.C., 1987: Tectonic subdivisions and evolution of Asia. Bulletin of the Technical University of Istanbul 40, 355-435. Sengor, A.M.C., 1989: The TethysideOrogenic System, an introduction, In: Sengor, A.M.C. (Ed.). Tectonic Evolution of the Tethyan Region. Kluwer, Dordrecht, pp. 1-22. Scotese, C.R., McKerrow, W.S., 1990: Revised world maps and introduction. In: McKerrow, W.S., Scotese, C.R. (Eds). PalaeozoicPalaeogeography and Biogeography. Geological Society Memoir 12, 1-21. Scotese, C.R., Golonka, J., 1992: Paleogeographic Atlas.Paleomap Progress Report 20-0692. Department of Geology, University of Texas at Arlington, 34pp. Scotese, C.R., Langford, R.P., 1995: Pangea and the paleogeography of the Permian. In: Scholle, P.A., Peryt, T.M., Ulmer-Scholle, D.S. (Eds.). The Permian of northern Pangea. Paleogeography, Paleoclimate and Stratigraphy, Vol. 1, Springer, Berlin, pp. 3-19. Sone, M., Metcalfe, I., 2008: Parallel Tethyan Sutures in mainland SE Asia: new insights for Palaeo-Tethys closure. Compte Rendus Geoscience 340, 166-179. Steiner, M., Ogg, J., Zhang, Z., Sun, S., 1989: The Late Permian -Early Triassic magnetic polarity time scale and plate motion of South China. J. Geophys Res., 94, 7343-7363. Takemoto, K., Halim, N., Otofuji, Y., Tran Van Tri, Le Van De, Hada, S., 2005: New paleomagnetic constraints on the extrusion of Indochina: Late Cretaceous results from the Song Da terrane, northern Vietnam. Earth. Planet. Sci. Lett., 229, 273-285. Tran Trong Hoa, 1996: Magmatic activities of Northwestern Truong Son belt in Mesozoic-Cenozoic. Material substances, forming conditions and mineral resource potential // J. Sci Earth. 18 (3), 218-227. Tran Trong Hoa, 2001: Division and Comparison of Permian-Triassic basaltoid complex of the Song Da zone. Journal of Geology A/265, 12-19, Hanoi, Vietnam (In Vietnamese). Van Der Voo, R., Fang, W., Wang, Z., Suk, D., Peacor, R., Liang, Q., 1993: Paleomagnetism and electron microscopy of the Emeishan basalts, Yunnan, China. Tectonophysics 221, 367-379. Yang, Z., Besse, J., 1993: Paleomagnetic study of Permian and Mesozoic sedimentary rocks from northern Thailand supports the extrusion model for Indochina. Earth Planet. Sci. Lett., 117, 525-552. Zhang, K.J., Cai, J.-X., 2009: NE-SW-trending Hepu-Hetai dextral shear zone in southern China: penetration of the Yunkai Promontory of South China into Indochina. Journal of Structural Geology 31, 737-748. Zhang, K.J., Cai, J.-X., Zhu, J.-X., 2006: North China and South China collision: insights from analogue modeling. Journal of Geodynamics 42, 38-51. Zhao, X.X., Coe, R.S., 1987: Palaeomagnetic constraints on the collision and rotation of North and South China. Nature 327, 141-144. Zhou, M.F., Arndt, N.T., Malpas, J., Wang, C.Y., Kennedy, A.K., 2008: Two magmaseries and associated ore deposit types in the Permian Emeishan large igneous  province, SW China. Lithos 103, 352-368. Zhou, Y., Lu, L., and Zheng, B., 1986: Paleomagnetic polarity of the Permian Emeishan basalt in Sichuan (in Chinese). Geol. Rev., 32, 465-469. Ziegler, A.M., Hulver, M.L., Rowley, D.B., 1997: Permian World Topography and Climate, In: Martinin, I.P. (Ed.). Late Glacial and Postglacial Environmental Changes.Oxford University Press, New York, pp.111-146. Ziegler, A.M., Gibbs, M.T., Hulver, M.L., 1998: A mini-atlas of oceanic water masses in the Permian Period. Proceedings Royal Society of Victoria 110, 323-343. Zijderveld, J.D.A., 1967: A.C. demagnetization of rocks: Analysis of results, In: Methods in paleomagnetism, edited by D.W. Collinson, K.M. Creer, and S.K. Runcon, 254-286, Elsevier, New York. Zonenshain, L.P., Kuzmin, M.I., Kononov, M.V., 1985: Absolute reconstructions of the Palaeozoic oceans. Earth and Planetary Science Letters 74, 103-116.