Science and Technology Development Journal - Natural Sciences

Journal Information
ISSN / EISSN : 2588-106X / 2588-106X
Current Publisher: Viet Nam National University Ho Chi Minh City (10.32508)
Former Publisher: Biomedical Research and Therapy (10.15419)
Total articles ≅ 377
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Viet Quoc Huynh, Quynh Nguyen-Thi-Nhu, Minh Duc Tran, Anh Ngoc Le, Phuoc Thanh Nguyen, Tuan Van Huynh
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.1006

Abstract:
Human emotion plays an important role in communication without language, and it also supports research on human behavior. In addition, electroencephalogram signals have been highly confirmed by researchers for reliability as well as ease of storage and recognition. So, the use of electroencephalogram to identify emotion signals are currently a relatively new field. Many researchers are targeting the key ideas in this research field such as signal preprocessing, feature extraction and algorithm optimization. In this paper, we aim to recognize emotion signals using Long Short Term Memory (LSTM) algorithms. Emotional signals dataset was taken from DEAP database of koelstra authors and associates to serve this research. The research will focus on accuracy and training time, and it will test different architectural types as well as the initials of LSTM. The obtained results show the 3-dimensional cubes's structure has better performance than the 2-dimensional cubes's structure. In addition, our research is also compared with other authors' studies to prove the effectiveness of the classification algorithm.
Tran Le, Huu Phuc Dang
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.980

Abstract:
This work studied the effects of Zn and N co-doping on the crystal structure, electrical properties, and photoelectric effects of p-typed Zn-N co-doped SnO2/n-Si heterojunction. Zn and N co-doped SnO2 films (ZNTO) were deposited on n-type Si substrates at 300oC in different sputtering gas mixture Ar/N2 (% N = 0%, 30%, 50%, 60%, 70 % and 80%) from 5 wt% ZnO doped SnO2 target by the DC magnetron sputtering method. The crystal structure, surface morphology, chemical composition, electrical properties, and photoelectric effects of ZNTO films were investigated by measurements such as X-ray diffraction, FESEM, AFM, EDS, Hall, and I-V. The results showed that all films had a rutile structure, and the SnO2 (101) reflection was dominant on the optimal fabrication of 70% N2. Substitution of Sn4+ by Zn2+ and O2􀀀 by N3􀀀 were determined by the X-ray diffraction pattern (XRD) and X-ray energy scattering spectrum (EDS). The lowest resistivity for the ZNTO-5-70 film was r= 6.5010􀀀2 W.cmwith carrier concentration n = 1.461019 cm􀀀3 and hole mobility m = 6.52 cm2.V􀀀1.s􀀀1 respectively. I-V characteristics of the p – ZNTO – 5 – y/n – Si under the illumination condition showed the p-type electrical properties and their application as optical sensors. The ZNTO – 5 – y films' optical response current characteristic had high sensitivity and good reproducibility.
Dũng Hoàng Văn, Anh Tuấn Thanh Phạm, Thư Nguyễn Bảo Lê, Trương Hữu Nguyễn, Thắng Bách Phan, Vinh Cao Trần
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.973

Abstract:
Climate change is promoting researches on materials which is capable of converting environmentally friendly energy, in which materials that convert heat into electricity are receiving significant attention, because their ability of converting heat to electricity not only generates the electricity but also contributes to slow down the consumption of fossil fuel. The existence of point defects in the semiconductors greatly effected properties of materials, especially thermoelectric properties. Therefore, the study of defects in materials is a popular research trend today. In this study, we focus on evaluating the existence of oxygen interstitial in CuCr1􀀀xMgxO2 [0.00 x 0.30] compounds, because oxygen interstitial greatly affected the thermoelectric properties of this material. Based on X-ray photoelectron spectroscopy (XPS) analysis, at the large ratio of Mg impurity x = 0.15, the compound had the highest percentage of oxygen interstitial and was also a good thermoelectric material. In addition, it could be also seen that CuCrO2 material being doped a large Mg doping ratio (x = 0.15) was suitable for thermal-to-electrical applications rather than the ones with a small ratio (x 0.05).
Long Hoang Nguyen, Thanh Ha Nguyen, Tuan Anh Dao, Ke Huu Nguyen, Hung Vu Tuan Le
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.971

Abstract:
This study investigated the effect of changing the density of Ag nanoparticles on the ZnO/Ag nanorod structure on the SERS substrate signal amplification ability. First, ZnO nanorods were fabricated by the sol - gel method combining with the chemical bath deposition method. Next, the Ag nanoparticles were decorated on ZnO nanorods by the DC magnetron sputtering method. The density and size of the modified Ag nanoparticles on the ZnO nanorods were changed by adjusting the sputtering times to 5, 10, 15 and 20s respectively. The optical properties of the material are characterized by UV - Vis and PL measurements. The surface morphology of ZnO nanorods and Ag nanoparticles were investigated by scanning electron microscope (SEM). X-ray diffraction measurement (XRD) is used to examine the crystal structures of materials. The composition and distribution of the chemical elements inside the material were investigated by Energy-dispersive X-ray spectroscopy (EDX). The ability of SERS substrates to amplify Raman signals was evaluated by measuring the R6G solution and investigating application for abamectin with a laser excitation wavelength of 532 nm. The results showed that SERS ZnO/Ag substrates with sputtering time of 15s gave the best ability to amplify SERS with the detection of R6G solution at 10􀀀9 M and abamectin at 50 ppm.
Tuấn Nguyên Hoài Đức, Trần Tiện Lợi Long Tứ, Lê Đình Việt Huy
Science and Technology Development Journal - Natural Sciences, Volume 5, pp 1032-1039; doi:10.32508/stdjns.v5i2.928

Abstract:
We built a model labelling the Predicate Argument Structure (PAS) for biomedical documents. PAS is an important semantic information of any document, because it reveals the main event mentioned in each sentence. Extracting PAS in a sentence is an important premise for the computer to solve a series of other problems related to the semantics in text such as event extraction, named entity extraction, question answering system… The predicate argument structure is domain dependent. Therefore, in Biomedical field, it is required to define a completely new Predicate Argument frame compared to the general field. For a machine learning model to work well with a new argument frame, identifying a new feature set is required. This is difficult, manual and requires a lot of expert labor. To address this challenge, we chose to train our model with Deep Learning method utilizing Bi-directional Long Short Term Memory. Deep learning is a machine learning method that does not require defining the feature sets manually. In addition, we also integrate Highway Connection between hidden neuron layers to minimize derivative loss. Besides, to overcome the problem of small training corpus, we integrate Deep Learning with Multi-task Learning technique. Multi-task Learning helps the main task (PAS tagging) to be complemented with knowledge learnt from a closely related task, the NER. Our model achieved F1 = 75.13% without any manually designed feature, thereby showing the prospect of Deep Learning in this domain. In addition, the experiment results also show that Multi-task Learning is an appropriate technique to overcome the problem of little training data in biomedical fields, by improving the F1 score.
Thai Thanh Tran, Yen Thi My Tran, Giang Hoai Tran, Hoai Ngoc Pham, Tinh Tran, Trang Thu Ngo, Tan Minh Lam, Quang Xuan Ngo, Vanreusel Ann, Veettil Kozhikkodan Bijeesh
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.835

Abstract:
Water can make a substantial contribution to human life for drinking as well as purposes related to human life and human nature. Because of increasing demand for water, there is a need for dam construction in preparation for agricultural purposes, drinking, industry and also flood control, power generation, etc. Simultaneously, they have had a considerable impact on the environment. A large range of potential impacts and hazards linked to the exploitation of dams and reservoirs, such as: (i) Major change in flow regime, thermal regime, physico-chemical cycles, (ii) reduction or loss of biological diversity, particular in aquatic species, (iii) greenhouse gas emissions, (iv) increases in the number of infectious disease and accumulation of heavy metals in food web...Therefore, there are various potential health risks of the environment and residents. However, whilst dam effects are very well documented elsewhere in the world, little or no information about negative effects of dams on the environment is available from Vietnam. Consequently, this paper provides a brief review of the environmental impact of dam constructions and after that, we will investigate some strategies to deal with the effects for Vietnam. By the way, we give some insight into ​​the first studies on the impacts of dams on the environment, which focuses on aquatic species was also noted in paper.
Ly Thi Thao Nguyen, Thai Le Tran, Dung Ngoc Bui, Thai Quoc Bui, Le-Thu Thi Nguyen, Lien-Hoa Dieu Nguyen, Hieu Tri Nguyen
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.981

Abstract:
Garcinia lanessanii Pierre belongs to the genus Garcinia of the Guttiferae (Clusiaceae) family. In Cambodia, people use this species to cure sore throat and tooth decay. However, chemical and biological study of this species has been not reported in the world until now. To contribute to chemical knowledge of the genus Garcinia in Viet Nam, we chemically investigated the species Garcinia lanessanii Pierre. The bark of this plant collected in the National Forest Lo Go – Xa Mat, Tan Bien ward, Tay Ninh province was dried, ground into powder and extracted in turn with n-hexane, chloroform and ethyl acetate solvents by using a Sohxlet system. Four flavonoids were isolated from the ethyl extract of G. lanessanii Pierre using column and thin layer chromatography on silica gel, RP-18 and Sephadex LH-20 with different solvents. Based on the analysis of 1D and 2D NMR spectra as well as comparison with literature, the structures of these compounds were elucidated as a flavanone, naringenin (1); two biflavonoids, volkensiflavone (2) and GB-2 (3), together with a biflavonoid glycoside, volkensiflavone-7-O-rhamnopyranoside (4). These compounds were isolated from G. lanessanii Pierre for the first time.
Ngoc Kim Bui, Hieu Trung Pham, Minh Pham, Phuc Duc Le
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.962

Abstract:
Metacarbonates located in Sa Thay, Kon Tum massif are distributed in ultramafic marble assemblage from Kham Duc (NP-e1kđ) complex.The main rock-formingminerals arecalcite and dolomite (40÷85%), olivine (5÷20%), pyroxene (5÷15%), and serpentine (5÷25%). Accessory minerals aretalc and epidote. Chemical composition of pyroxene in metacarbonate was determined by EPMA method: the composition of pyroxene is diopsite (Wo49.5 En50.1Fs0.4 to Wo50.8En48.9Fs0.2). The rim of pyroxene grains generally have higher wollastonite than core(49.9÷50.8%).Metacarbonates originated from metamorphic sources with three main stages: regional metamorphism, superimposed metamorphismand hydrothermal metamorphism stages. With each stage, they have different color characteristicsto create a variety of color. Metacarbonateshave quality characteristicsofcolor, durability, pattern, diversity, and low radioactivity. These make the metacarbonates suitable for gemstone applications.
An Nang Vu, Ngoc Hoa Thi Le, Linh Thi My Nguyen, Khoa Tien Le, Hieu Van Le
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.918

Abstract:
A combination between the nanostructured photocatalyst and cellulose-based materials promotes a new functionality of cellulose towards the development of new bio-hybrid materials for water treatment and renewable energy applications. In this study, nanocellulose (CNC) was synthesized from sugarcane bagasse (SCB) biomass via formic /peroxyformic acid process treatment and acid hydrolysis at an atmospheric pressure. The resulting CNC of sugarcane bagasse were characterized by crystallinity index, chemical structure and morphology. X-ray diffraction (XRD) analysis revealed that the crystallinity increased with successive treatments. Images generated by TEM showed that CNC was rod-like in morphology, average diameter and length of 10 nm and 410 nm, respectively. The obtained CNC was used as a biotemplate for the synthesis of copper oxide (CuO) nanostructures through in - situ solution casting method. The photo-Fenton catalytic activity was evaluated via the degradation of methylene blue under sunlight irradiation with H2O2 as a oxidizing agent. The methylene blue degradation ratio of CuO/ CNC composite could achieve 98% in 150 min. The addition of H2O2 enhanced photocatalytic activities of the CuO/CNC. H2O2 not only prevented the recombination of charge carriers by accepting the photogenerated electrons and holes effectively but also produced additional OH.
Hà Tuyết Minh Nguyễn, DongQuy Hoang, Thị Chi Phạm
Science and Technology Development Journal - Natural Sciences, Volume 5; doi:10.32508/stdjns.v5i2.1011

Abstract:
Bis(2-hydroxyethyl) terephthalate (BHET) obtained from waste poly(ethylene terephthalate) bottles was used to synthesize polyurethane foams (B-PUF) and the fireproof B-PUF in the presence of nonhalogen flame retardant, namely, aluminum hydrogen phosphonate (AHP). Loading of 25 php AHP was needed for B-PUF/AHP to achieve UL-94 V-0 rating. The thermal stability of B-PUF was improved with the addition of AHP through the thermogravimetric analysis (TGA) results. In addition, other properties such as density and foam structure were also investigated. The outcomes of this study also confirmed that the B-PUF prepared from recycled PET not only were composed of a high percentage of waste poly(ethylene terephthalate), which could help reduce the amount of recycled polymer materials and improved waste management but also met the high demands for the fire safety of polymer applications.
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