http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/issue/feed Science and Technology Development Journal - Natural Sciences 2020-02-16T09:34:28+00:00 Phuc Van Pham pvphuc@vnuhcm.edu.vn Open Journal Systems http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/864 Optimization of protein extraction from green algae Chaetomorpha sp. by response surface methodology 2020-02-16T09:34:28+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_864_cover_en_US.png Bach Ngoc Minh phamvanphuc2308@gmail.com Huynh Hoan My phamvanphuc2308@gmail.com Hoang Kim Anh phamvanphuc2308@gmail.com Ngo Ke Suong phamvanphuc2308@gmail.com <p>Green brackish algae <em>Chaetomorpha</em> sp. are easily found in shrimp ponds in Mekong Delta, Vietnam. They can also be co-cultured with shrimps in brackish water shrimp ponds to increase shrimp health and yield. Chaetomorpha sp. algae contain high amount of protein from 10 to 20% w/w db, including water soluble protein and alkaline-soluble protein with over 88% total protein. Dried material were used for protein extraction by using cellulase enzyme (Crestone Conc., Genecor) and NaOH solution. In this research, we optimize the extraction condition of protein from green algae <em>Chaetomorpha</em> sp. by using response surface methodology (RSM). At optimal extraction conditions, dried material was used for protein extraction by using cellulase enzyme (Crestone Conc., Genecor) with the enzyme dosage of 121 UI/g db at 40<sup>0</sup>C during 90 mins. After extraction, the slurry was centrifuged to separate the algae biomass residue to extract the alkaline-soluble protein. The protein extraction yield by using cellulase enzyme was 38.921 mg/g db. After that the, algae biomass residue was extracted by a 1.2% NaOH solution for 78 mins at 50<sup>0</sup>C. The protein extraction yield was 68.651 mg/g db. The total protein extraction yield was 105.755 mg/g db. The extraction yield was increased 10.33% when using the response surface methodology. Concentrated algae protein can be used as a good protein source for food and feed products.</p> <p>&nbsp;</p> 2019-12-22T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/867 Initial study of lipid accumulation in green algal Haematococcus pluvialis Flotow cultured in liquid Bold’s Basal medium aerated 2020-02-16T09:34:25+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_867_cover_en_US.png Nguyen Tran Dong Phuong phamvanphuc2308@gmail.com Le Huyen Ai Thuy phamvanphuc2308@gmail.com Bui Trang Viet phamvanphuc2308@gmail.com <p>The fresh green algal Haematococcus pluvialis Flotow was proved to be the starting material for the production of biofuel, high lipid content along with astaxanthin, a high value colorant. In this study, lipid accumulation in H. pluvialis cultured in liquid Bold’s Basal medium aerated was investigated for a period of 12 weeks. Lipid accumulation was evaluated through the expression of two genes: BC (biotin carboxylase, initial gene) and FATA (acyl-acyl carrier protein thioesterase, end gene) in the process of fatty acid biosynthesis with Real-time RT-PCR, lipid determination by Nile Red and biodiesel quantifying by transesterification. The results showed that the expression of two BC and FATA genes was recorded at all weeks of culture. However, the expression of BC and FATA genes increased gradually from the week 9 (1.3, 4.1, respectively) to week 11 (1.7, 30.9, respectively). Meanwhile, yellow fluorescence in the microalgal cells showed that lipid appeared from week 6 to week 12. The obtained biodiesel increased slowly from week 8 (0.036 mg/mL) to week 12 (0.041 mg/mL). At week 11, the expression values of both BC gene (1.7) and FATA gene (30.9) were maximized, leading to the highest biodiesel content at the week 12.</p> 2019-12-30T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/593 Measurement of asphalt pavement layer thickness of road using ground penetrating radar 2020-02-16T09:34:27+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_593_cover_en_US.png Nguyen Huu Tam thegioicuatam@gmail.com <p>Thickness and moisture content of the asphalt surface are two important parameters, contributing to the assessment of road quality. Typically, these parameters are measured by drilling and sampling, causing structural damage, time loss and intermittent data acquisition. Ground Penetrating Radar is a geophysical method that uses electromagnetic waves at high frequency ranges to form pulses into the ground, so it has good resolution and accuracy. By measuring above the road surface, the data obtained can reveal the boundaries of shallow layers without causing destruction. Relying upon algorithms for wave impulse, we can calculate the value of earth wave velocity, characteristic of the wave propagation velocity in the first subclass. Therefore, the surveyor can accurately determine the thickness and moisture content of asphalt on the entire route, the accurate determination of layer thickness and defects of surface layer of plastic contributes to improving and restoring road quality. This paper presents the results of using 700 MHz and 1000 MHz frequencies to conduct field surveys and collect data, in order to verify the accuracy of processing algorithms, and evaluate the errors of initial calculation results. The use of Ground Penetrating Radar to measure the thickness of the plastic layer is a potenial method to increase the effectiveness of road quality appraisal in the future.</p> 2019-12-30T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/514 Effect of moisture on technological properties of corn starch modified by the electron beam irradiation 2020-02-16T09:34:24+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_514_cover_en_US.png Nguyen Dang My Duyen myduyen@hcmute.edu.vn Pham Ngoc Viet phamvanphuc2308@gmail.com <p>Electron beam irradiation is one of the most effective starch modification methods. Moisture is one of the factors that is affected by the irradiation via the free radical formation. The effect of the moisture content on the technological properties of irradiated starch samples was studied. The moisture content of corn starch samples in this study was adjusted at 9.08, 12.96, 15.06, 20.39 and 29.09% (w w). Corn starch samples were irradiated at 5 kGy. Color, free acid, solubility, swelling, transparency, syneresis and starch gel structure were studied to elucidate the effect of the moisture on technological properties of corn starch treated by electron beam. The results showed that electron beam radiation caused starch samples at different moisture to break into small molecules due to the separation of the glycosidie bonds. Thus, free acid, swelling, solubility of irradiated starch samples were higher than those of natural starch samples and were increased with low moisture content. The results also indicated that electron beam treatment increased the syneresis of irradiated starch samples. The texture profile analysis (TPA) of starch gel structure showed that textural properties such as hardness, elasticity and chewiness of irradiated starch samples were higher than those of natural starch samples.</p> 2020-01-01T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/720 Data analysis of two-dimensional ground penetration radar profiles in three-dimensional space to study of underground objects 2020-02-16T09:34:22+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_720_cover_en_US.png Duy Hoàng Đặng danghoanghuy0706@gmail.com Cường Văn Anh Lê lvacuong@hcmus.edu.vn Trung Hoài Đặng hoaitrungag@gmail.com Vấn Thành Nguyễn ntvan@hcmus.edu.vn <p>The Ground Penetrating Radar can be effectively applied in ground surface exploration geophysics. Underground anomalies are shown in the ground penetratingradar slices in the form of signals having similarity in amplitude and phase. Typically, each point-scattering object can be seen as a form of hyperbola. During the Ground Penetrating Radar measurement in an urban environment, the data including information of high frequency electromagnetic waveforms were easily affected by civil noise (human activities, etc.). Shielded antennas could help to eliminate mostly the civil noise, but processing and analysis of the data were still difficult because of attenuation of electromagnetic waves and wave energy dispersion during their propagation in the ground environment. Due to the field geometry condition, 2D profiles were conducted. In order to analyze and interpret data effectively, we processed each 2D profile separately and located all the 2D profiles into the 3D dimensional space for enhancing the ability of illuminating potential 3D anomalies and confirming the reliability of the data interpretation. We studied the data measured at an industrial company at Nhon Trach district, Dong Nai province, Vietnam. Results from the data analysis of ground penetration radar reflected the object in three-dimensional space.</p> 2020-01-09T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/638 The scattering time of electrons in a GaAs/InGaAs/GaAs quantum well including temperature and exchange-correlation effects 2020-02-16T09:34:23+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_638_cover_en_US.png Truong Van Tuan tuanbo83@gmail.com Nguyen Quoc Khanh nqkhanh@hcmus.edu.vn Vo Van Tai vovantai7411979@gmail.com <p>The ratio of the scattering and single-particle relaxation time of a quasi-two-dimensional electron gas (Q2DEG) in a finite lattice-mismatched GaAs/InGaAs/GaAs quantum well was investigate at zero and finite temperatures, taking into account the exchange-correlation effects via a local-field correction with three approximations for the LFC, G = 0, GH, and GGA. We studied the dependence of the surface roughness, roughness-induced piezoelectric, remote and homogenous background charged impurity scattering on the carrier density and quantum well width. In the case of zero temperature and Hubbard local-field correction our results reduced to those of different theoretical calculations. At low density, the exchange-correlation effects depend strongly on the ratio τt/τs. While at high density many-body effects due to exchange and correlation considerably modified the ratio of the scattering and single-particle relaxation time. We found that, for densities and temperatures considered T = 0,3TF in this study, the temperature affected weakly on the time ratio for four scatterings. Furthermore, with the change of quantum well width, the effect of LFC and temperatures act on the ratio τt/τs are negligible for the roughness-induced piezoelectric and remote charged impurity scattering, and are notable for the surface roughness and homogenous background charged impurity scattering.</p> 2020-01-09T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/572 Chemical constituents of the leave of Gnetum gnemon L. 2020-02-16T09:34:13+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_572_cover_en_US.png Tho Huu Le lhtho@hcmus.edu.vn Hai Xuan Nguyen nxhai@hcmus.edu.vn Truong Nhat Van Do dvntruong@hcmus.edu.vn Trinh Cong Pham congtrinh4029@gmail.com Truc Thien Lam lamthientruc1802@gmail.com Mai Thanh Thi Nguyen nttmai@hcmus.edu.vn <p>(Vietnamese name; L.), which belongs to the family, is an evergreen and perennial tree that is widely cultivated in Southeast Asia. In Vietnam, leaves of the species are used as an ordinary vegetable in many regions. The aim of this research is to investigate the chemical constituents of G. leaves collected from Lam Dong province, Vietnam. The fresh leaves were collected, dried, cut into small species, and extracted with ethanol to the extract. By using the column chromatography method together with thin layer chromatography on a normal phase silica gel with different solvent systems on the extract of the dried leaves of G. L., we isolated five pure compounds. The structures of 1-5 were elucidated by analyzing nuclear magnetic resonance (NMR) data. The result was confirmed by comparison with publish data including (1), acid (2), acid (3), (4), and (5). To the best of our knowledge, compounds 1-3were isolated from this plant for the first time. This study is to provide a comprehensive overview of of G. , and possibly make recommendations for further research.</p> 2020-02-13T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/641 Petrographical, petrochemical characteristics of Hòn Rồng massif granitoids, Cam Ranh, Khánh Hòa 2020-02-16T09:34:10+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_641_cover_en_US.png Nguyen Kim Hoang nkhoang@hcmus.edu.vn Lam Van Phuong phamvanphuc2308@gmail.com <p>Hòn Rồng massif granitoid has a high mountainous terrain, with an absolute height of 728 m, relatively equal, slightly extended in the Northwest-Southeast direction, occupying an area of ​​about 29 km<sup>2</sup>. Petrographical composition is mainly medium - grained biotite granite (phase 2), minor is fine- grained biotite granite (phase 3), vein rocks are aplite granite and pegmatite and&nbsp; a little of xenolith of granodiorite in medium - grained biotite granite. Medium-grained biotite granite: major mineral composition (%): plagioclase (oligoclase) 25–35, quartz 30, orthoclas 25, biotite 5 - 8 and few hornblend; fine-grained granite (%): plagioclase (oligoclase) 30 - 35; quartz 30 - 35; feldspar kali (orthoclase, and microclin) 30, biotite 3 - 5; accessory mineral is zircon, orthite, apatite, sphen, and very little ore minerals (about ​​2%); epimagmatic minerals including: chlorite, epidot, kaolinite, sericite, carbonate, sausorite-replaced association. Rocks are altered alkalization strongly (albitization and microlinization), and minor are chloritization, epidotization and sericitization. Averaged chemical compositions (%)SiO<sub>2</sub>: 69.07–72.07; total alkali(K<sub>2</sub>O+Na<sub>2</sub>O) 7.35–7.96. Ratio of K<sub>2</sub>O/Na<sub>2</sub>O 1.04, low TiO<sub>2</sub> (0.24–0.37). Ratios of A/CNK 1.02–1.09, Rb/Sr: 0.27–1.62; Ba/Sr: 1.82–2.56, Ba/Rb: 1.58–7.13; K/Rb: 0.42–0.62; Ca/Sr: 0.21–0.47; the value of Eu anomalies is low. Granite belongs to calc-alkaline, aluminum content is from medium to high; K-Na alkaline series, I-granite type. Granitoid had been formed in plutonic - volcanic arc of subduction-zone. Compared with the granitoid formations in South Vietnam territory, Hòn Rồng massif granitoid belongs to phase 2 (main) and phase 3 (minor) of Đèo Cả complex with late Kreta age.</p> 2020-02-13T16:03:11+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/649 New sufficient criteria for epsilon-contraction of a class of nonlinear diference system with continuous time 2020-02-16T09:34:11+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_649_cover_en_US.png Đặng Lệ Thuý thuydl@uit.edu.vn Cao Thanh Tinh tinhct@uit.edu.vn Lê Trung Hiếu lthieu@dthu.edu.vn Lê Huỳnh Mỹ Vân vanlh@uit.edu.vn <p>Contraction property of dynamical systems, especially difference systems, is one of the qualitative properties which have attracted much attention from many researchers for recent decades. Contraction of dynamical systems has many practical applications which means that two trajectories of the system convergence to each other when the time reaches to positive infinity. In this paper, by improving some existing approaches, we present a new approach to contraction problem of a class of nonlinear time-varying delay difference system with continuous time. We generalize the definition of contraction to -contraction. Then, we give some new explicit sufficient criteria for -contraction and global exponential stability of the mentioned system. Furthermore, we investigate-contraction of perturbed difference systems with continuous time under nonlinear perturbations in which perturbations are general time-varying functions. Then we obtain a new explicit-contraction bound for such systems subject to nonlinear time-varying perturbations. The obtained theorems generalize some existing results in the literature as particular cases. An example is given to illustrate the obtained results.</p> 2020-02-13T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/881 Study on components and structure of difference Vietnamese starch sources 2020-02-16T09:34:09+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_881_cover_en_US.png Vu Tien Trung phamvanphuc2308@gmail.com Ha Thuc Chi Nhan phamvanphuc2308@gmail.com <p>In this study, we focused was on the determination of amylose and amylopectin components of starch from different plant sources in Vietnam by UV-VIS spectroscopy. Besides, the distribution of natural starch structure and crystallization level of different starches was also evaluated by FT-IR, XRD analysis methods. By UV-VIS absorption spectroscopy, we could quantify amylose and amylopectin contents which are the two main components in different starch sources in Vietnam. Our results have showed that corn starch sample had the highest amylose content at 28.22%wt. The degree of morphology in the structure is evaluated through FT-IR spectroscopy method and the crystallization ability of starch was determined by XRD diffraction method. These results showed that although the amylose content of arrowroot starch sample (27.24%) is higher than that of cassava starch (10.31%) or rice starch samples (17.10%), but the tightness rearrange level in the structure of dong starch is the smallest (0.2089) compared to cassava starch (0.2793) or rice starch (0.6645). After all these effective results, starch sample having the good properties and degree of crystallization as well as suitable amylose pectine content will be selected to for further plasticization and modification for the application in elaboration of biodegradable starch based composite materials.</p> 2020-02-14T00:00:00+00:00 ##submission.copyrightStatement##