Abstract: Lignin plays a crucial role as a structural material of plant cell walls and is also known as a significant renewable resource that has the potential to be a raw material for producing high value chemicals. The article aimed to research on the extraction of lignin from sugarcane bagasse by environmental method using deep eutectic solvents (DESs) containing choline chloride and formic acid. In the process, lignins dissolved in DESs were isolated from the solution by dilution with water and ethanol. The obtained lignin samples were characterized with UV - Vis (Ultraviolet – visible spectroscopy), FT-IR (Fourier-transform infrared spectroscopy), GPC (Gel permeation chromatography), and 1H-NMR (Proton nuclear magnetic resonance). The initial results showed that the extracted lignin obtained adequately distinct functional groups and the weight average molecular mass of the lignin was about 28265 g/mol.

Abstract: The nanostructure of zinc oxide has excellent potential in gas sensing applications to detect and monitor toxic gases in the atmosphere. Appropriate nanostructures can enhance the performance of gas sensors. In this study, we report the controlled fabrication of ZnO nanorods of different sizes by a simple hydrothermal method, which can be applied to detect NO2 toxic gas efficiently. The size of the nanorods was controlled by varying the amount of D-Glucose. The morphology and crystal structure of the materials were analyzed using advanced techniques such as field-emission scanning electron microscopy, X-ray diffraction patterns, and energy-dispersive X-ray spectroscopy. The sensor's response based on ZnO nanorods at 2 ppm NO2 is 13.3 and 18.8 times higher than that of 500 ppm CO and NH3, respectively. In addition, the sensor also exhibits good selectivity and repeatability for NO2 toxic gas; The optimum working temperature is about 150 oC. \[H_2= H_1+ H_1 \tag{1}\] H2 hoac H2

Abstract: The paper presents the initial results of the study of volcanic cave system and its typical formations in Krongno Volcano Geopark (KVG), Dak Nong, Vietnam. The volcanic caves have been discovered since 2007, under UNESCO sponsored the scientific project, are seen as unique geological heritages. The collaborative surveys and studies between Vietnamese geologists and the members of the Non-Profit Organization, Vulcanospeleological Society of Japan have discovered and surveyed 45 caves, and detailed mapping 20 caves. Using a complex of adequate methods, especially Remote Sensing image interpretation method, Surveying and mapping lava cave method, K/Ar dating isotopic analytical method and Current methodology, the studies aim to affirm endogenous origin of the lava cave system, the formation mechanism, as well as the typical formations of the caves. Up to date, the lava caves and interior formation in lava caves in KVG have been examined and evaluated in term of geological nature and recognized as pillar geological heritages of the Geopark.References Allred K., AllredC., 1997. Development and morphology of Kazumura Cave, Hawaii. Journal of Cave and Karst Studies, 59(2), 67-80.Allred K., Allred C., 1997. Tubular lava stalactites and other related segregations. Journal of Cave and Karst Studies, 60(3), 131-140.Barnabás Korbély, 2014. Diverse volcanic features as dominant landscape elements and pillars of geotourism in the Bakony-Balaton Geopark, Hungary. Abstract Book Workshop “Geoparks in volcanic areas: sustainable development strategies”, October 29th to November 1st, 2014. Terceira and Graciosa Islands, Azores Global Geopark, 35-38.Bird Deanne K., et al., 2014. Southern Iceland: Volcanoes, Tourism and Volcanic Risk Reduction.In Volcanic Tourist Destinations. Springer, Editors: Erfurt-Cooper, Patricia (Ed.). ISBN: 978-3-642-16190-2, 35-46. Cooper Malcolm J.M., 2014. Volcanic National Parks in Japan.In Volcanic Tourist Destinations. Springer, Editors: Erfurt-Cooper, Patricia (Ed.). ISBN: 978-3-642-16190-2, 231-246.Dave Bunnell, 2014. The virtual lava cave Created: August 4, 2000.Last update: December 16, 2014. Reviewed by Kevin & Carlene Allred. Available at: 〈 http://www.goodearthgraphics.com/virtual_tube/virtube.html). Date accessed: 02 May 2018.Gadányi P., 2010. Formation, types and morphology of basalt lava caves. PhD. thesises. University of Pécs Faculty of Natural Sciences Doctoral School of Earth Sciences, Hungary, 1-19.Gaki-Papanastassiou, Kalliopi, et al., 2014. Volcano Tourism in Greece: Two Case Studies of Volcanic Islands.In Volcanic Tourist Destinations. Springer, Editors: Erfurt-Cooper, Patricia (Ed.). ISBN: 978-3-642-16190-2, 69-87.Honda T., Tachihara H., 2015. Vietnam Volcanic Cave Survey. e-NEWSLETTER, UIS Commission on Volcanic caves, 69, 11-12. Honda T., Tinsley J.C., 2016. Classification of lava tubes from Hydrodynamic models for active lava tube, filled lava tube and drained lava tube. 17th International Vulcanospeleology symposium in Hawaii, USA. Sponsored by the Commission on volcanic caves of the International Union of Speleology.Larson C.V., 1991. Nomenclatures of lava tube features. 6th International Symposium on Vulcanospeleology in Hawaii. Published by the National Speleological Society, 231-248.Laumanns M., 2013. Important Lava Tube Caves found in Dong Nai Province Southern Vietnam. e-NEWSLETTER, UIS Commission on Volcanic caves, 67, 13. Machado M., Lima E., 2014. Geotourism and sustainable development partnerships in the Azores Geopark. Abstract Book Workshop “Geoparks in volcanic areas: sustainable development strategies”, October 29th to November 1st. Terceira and Graciosa Islands, Azores Global Geopark, 45-48.Moreira Jasmine Cardozo, et al., 2014.Tourism and Volcanism in the Canary Islands, Spain. In Volcanic Tourist Destinations.Springer, Editors: Erfurt-Cooper, Patricia (Ed.). ISBN: 978-3-642-16190-2, 47-55.Nelson S.A., 2017. Volcanoes and Volcanic Eruptions.EENS 1110. Physical Geology.Tulane University. New Orleans, USA.Nguyen Duc Thang (Ed.), 1989. Geology and Mineral Resources of Ben Khe - Dong Nai sheet at scale 1:200,000. General Department of Geology and Minerals of Vietnam. Hanoi. Nunes, João Caros., 2014. The Azores Archipelago: Islands of Geodiversity.In Volcanic Tourist Destinations. Springer, Editors: Erfurt-Cooper, Patricia (Ed.). ISBN: 978-3-642-16190-2, 57-67.Nunes João Caros., 2014. Azores Geopark volcanoes and volcanic landforms. Valuating the Azorean geodiversity and geosites through the geotourism. Abstract Book Workshop “Geoparks in volcanic areas: sustainable development strategies”, October 29th to November 1st. Terceira and Graciosa Islands, Azores Global Geopark, 41-43.Ogawa T., 1993. On lava caves in Japan and vicinity.Proceedings of the Third International Symposium on Vulcanospeleology, 56- 73.Patricia Erfurt-Cooper, 2014. Volcanic Geo-heritage.Sustainable Tourism Development in Volcanic Regions: Geoparks, National Parks and World Heritage Sites. Abstract Book Workshop “Geoparks in volcanic areas: sustainable development strategies”, October 29th to November 1st. Terceira and Graciosa Islands, Azores Global Geopark, 23-25.Peterson D.W., Holcomb R.T., Tilling R.I., Christiansen R.L., 1994. Development of lava tubes in the light of observations at Mauna Ulu, Kilauea Volcano, Hawaii. Bulletin of Volcanology, 56, 343-360. 

Abstract: Aluminum doped zinc oxide was prepared by magnetron sputtering methods at room temperature using a ZnO ceramic target doped 2%wt by Al2O3. The optical transmittance of the films is higher than 80% in the visible range. A direct bandgap type was reached by controlling deposition conditions; the bandgap value was in the range between 3.2 eV and 4.2 eV. Good electrical and optical properties were obtained for the films deposited by an appropriate co-sputtering of ZnO and Al targets. These films with a resistivity, about 1.3´10-2W.cm, and a transmittance, higher than 80%, can be applicable for transparent conducting electrodes.

Abstract: This paper presents velocities of present-day tectonic movement and strain rate in the East Vietnam Sea (South China Sea) and surroundings determined from GPS campaigns between 2007 and 2010. We determine absolute velocities of GPS stations in the ITRF05 frame. The result indicates that GPS stations in the North of East Vietnam Sea move eastwards with the slip rate of 30 - 39 mm/yr, southwards at the velocities of 8 - 11 mm/yr. Song Tu Tay offshore moves eastwards at the rate of ~24 mm/yr and southwards at ~9 mm/yr. GPS stations in the South of East Vietnam Sea move to the east at the rate of ~22 mm/yr and to the south at the velocities of 7 - 11 mm/yr. The effect of relative movement shows that the Western Margin Fault Zone activates as left lateral fault zone at the slip rate less than 4 mm/year.In Western plateau, the first result from 2012 - 2013 GPS measurement shows that the velocities to the east vary from 21.5 mm/yr to 24.7 mm/year. The velocities to the south vary from 10.5 mm/yr to 14.6 mm/year. GPS solutions determined from our campaigns are combined with data from various authors and international projects to determine the strain rate in the East Vietnam Sea. Principal strain rate changes from 15 nanostrain/yr to 9 nanostrain/yr in the East Vietnam Sea. Principal strain rate and maximum shear strain rate along the Red River Fault Zone are in order of 10 nanostrain/year. East Vietnam Sea is considered to belong to the Sunda block.

Abstract: The appearance of antibiotic sulfamethoxazole (SMX) in natural environments poses a potential risk to human health and ecology. Among many developed treatment techniques to remove and degrade SMX from an aqueous environment, photodegradation using the phase-pure TiO2 nanoparticles (NPs) in brookite structure as an active photocatalyst could be considered as a novel and effective strategy. The photocatalytic degradation of SMX in aqueous media followed an apparent first-order kinetics under the simulated UV-A irradiation. The higher the photocatalysts load, the higher photocatalytic efficiency. The SMX photodegradation over brookite nanoparticles depended on the pH of the SMX solution that was related to changes in chemical isomers of SMX molecules in the range of pH values between 2.0 and 10.0. The degradation efficiency was highest at pH 10.0 (up to 88 % after 180 min under UV-A irradiation) when SMX was in anionic form. With real matrices, the presence of metal ions (in mineral water) and fact-finding organic matter (in surface water) had a small effect on photodegradation efficiency due to either the complexation between SMX with metal ions or the inhibition of free radicals. The obtained results confirmed that the nano-sized TiO2 brookite photocatalyst has a high potential for water and wastewater remediation.

Abstract: Organometal halide perovskite materials have shown high potential as light absorbers for photovoltaic applications. In this work, perovskite planar solar cells were fabricated on corning substrates with the structure as follows: the first layer made of tantalum-doped tin oxide as transparent contact material, followed by sputtering niobium-doped titanium oxide as the compact electron transport layer; covered with perovskite CH3NH3PbI3 as the light harvester by combination between spin-coating and dipping methods; CuSCN was evaporated as the hole transport layer; the final thin Al/Ag electrodes were deposited. This configuration is shortly described as Al/TTO/NTO/CH3NH3PbI3/CuSCN/Ag. Such heterojunctions are expected to be suitable for the development of efficient hybrid solar cells. The fabricated cells were measured under the air mass 1.5 illumination condition, showed the rectification effect and exhibited a power conversion efficiency of 0.007%, with a open circuit voltage of 53.2 mV, a short circuit current of 0.36 mA/cm2, and a form factor of 37%. The power conversion efficiency will be further optimized in near future.

Abstract: The Garcinia genus belonging to the Clusiaceae family (Guttiferae) has been reported to be a rich source of polyisoprenylated benzophenones, xanthones and biflavonoids with various biological activities. Garcinia fagraeoides A.Chev is an evergreen hardwood tree found only in the north provinces of Viet Nam and Guangxi province of China. Its stem bark and leaves have been used in Vietnamese traditional medicine for treatment of malaria and dermatitis diseases. In our continuing studies on chemical constituents and biological activities from the genus Garcinia, the phytochemical of Garcinia fagraeoides’s stem bark collected from Thua Thien Hue province was investigated. Repeated chromatography steps over silica gel and Sephadex LH-20 of the dichloromethane partition from the methanol extract of  Garcinia fagraeoides’s stem bark led to the isolation of five compounds including one polyisoprenylated benzophenone (isogarcinol (1)), two tetraoxygenated xanthones (rubraxanthone (2), a-mangostin (3)), ferulic acid (4), and pyromeconic acid (5). Their structures were elucidated mainly by analysis of their 1D, 2D NMR spectroscopy and ESI-MS data, and by comparison with reported data. The absolute configuration of isogarcinol (1) was determined by comparison of its experimental optical rotation and NMR data with the values of its stereoisomer. This is the first reported isolation of compounds 1-5 from the stem bark of Garcinia fagraeoides.

Abstract: Bach Long Vi island is an offshore district in the centre of the Gulf of Tonkin in Vietnam and administratively belongs to Hai Phong city. The island surrounded by abundant marine ecosystems with high biodiversity is one of 16 marine protected areas approved by the Prime Minister of Vietnam on 26/5/2010 according to the Decision No.742/QD-TTg. Currently, in addition to the main service of economic activities as fishery logistics, Bach Long Vi island still remains the wild features with beautiful scenery, fresh air and the diversity of marine species that are suitable for the development of eco-tourism and resorts. Although tourism at present is not developed yet, its potentials are promising. Deploying zone travel cost method (ZTCM), tourism potentials based on ecosystem services of Bach Long Vi island were estimated at 5.4 billion VND (Vietnamese currency). The value can be much higher if the infrastructure of the island is improved and the island is accessible more easily. Tourism potential valuation and identification of the advantages of the island strongly support tourism planning in the future.