http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/issue/feed Science and Technology Development Journal - Natural Sciences 2020-11-27T14:56:18+00:00 Phuc Van Pham pvphuc@vnuhcm.edu.vn Open Journal Systems http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/578 Study on treatment of pesticides-containing wastewater by model combining of the pre-biotreatment and photocatalytic TiO2 2020-11-27T14:56:18+00:00 Ho Truong Nam Hai htnamhai@gmail.com Nguyen Ly Sy Phu nlsphu@hcmus.edu.vn To Thi Hien tohien@hcmus.edu.vn <p>In the current period, with the development of economy, science, and technology, people's lives have been improved, leading to increasing demand for water use. Thus, one of the main current concerns is the increased pollution of surface water and groundwater. Especially water pollution by pesticides is a serious problem. In this study, the wastewater treated system, which is including the aerobic biological process and photocatalytic TiO<sub>2</sub>, used to evaluate the effective treatment of pesticides. Self-generated wastewater was added by a group mixed 8 types of Organochlorine pesticides (OCPs): Tetrachloro-m-xylene,b -HCH,d - HCH, Heptachlor – epoxide, 4,4'- DDE,b -Endosulfan, Endrin – aldehyde, Endosulfan – sulfate and 5 types of Organophosphate pesticides (OPPs): Diazinon, Malathion, Parathion, Ethion, Trithion. The results showed that the COD removal efficiency was over 89,09% for the whole system when maintaining the load of 0,78 kgCOD/m<sup>3</sup>. day, total retention time was 16 hours. Five types of OPPs was thoroughly treated after going through the system based on its easily biodegradable. For OCPs, the treatment efficiency through the biological process is not high, 6/8 types about 5 - 27% but through photocatalytic TiO<sub>2</sub>/UV, the treatment efficiency increased 67 - 100% for each type. The results obtained in the study show that the use of the method of combining biology and AOPs is effective for wastewater difficult to treat as pesticides.</p> 2020-10-17T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/666 Assesment Assessment of X-Ray converter for electron beam radiation processing facility 2020-11-27T14:56:15+00:00 Nguyen Anh Tuan ntuan3584@gmail.com Chau Van Tao phamvanphuc2308@gmail.com <p>Recently, a high energy electron beam from accelerators studied on the application for foods and medical devices irradiation, therapy, denature material, discolored semi-precious stones and degradation of environment pollution (Gas, Water, and Sludge Waste). The advantages of electron beam from accelerators are high power density and easy focusing on the target, but electron beam is only useful to irradiate on the surface of the irradiation product because their penetration is short. In order to irradiate high area density products, the X-ray converter is used to generate photon (bremsstrahlung effect). In this article, converting efficiency and direction of X-ray emission is measured by film dosimeter and simulated by MCNP-4c2 code. Measurement and simulation results show that converting efficiency depends on materials of the targets and electron energy, the converting efficiency of Ti – H2O – Pb converter at electron beam energy 5.0 MeV, 7.5 MeV, and 10.0 MeV are 5.57 %, 7.12 %, and 13.54 %. Ti – H2O – Pb converter is made up of 3 layers of Ti wrap material with the function of bearing, heat resistance, circulating cooling water between Ti and Pb layers to cooling, so it is applied for the accelerator.</p> 2020-10-17T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/893 Performance of full-cell Na-ion with NaNi1/3Mn1/3Co1/3O2 cathode material and different carbonate-based electrolytes 2020-11-27T14:56:13+00:00 Hoang Van Nguyen nvhoang@hcmus.edu.vn Minh Le Nguyen minhnguyen29111998@gmail.com Man Van Tran tvman@hcmus.edu.vn Nhan Thanh Tran ttnhanhhh@gmail.com Phung My Loan Le lmlphung@hcmus.edu.vn <p>The battery performance not only depend on the electrodes nature but also depend on the choice of electrolyte consisting of salts and organic solvents. The development of electrolytes compatible with both cathode and anode materials is essential for enhancing the performance of practical full-cell Na-ion batteries. Among electrode with difference Ni/Mn/Co ratio, NaNi<sub>1</sub>/3Mn<sub>1</sub>/3Co1/3O<sub>2</sub> (NMC) showed the best stable cycling. Besides, carbonaceous anode materials such as hard carbon (HC) are attracting due to it low cost, high gravity/volumetric capacity. In this work, the electrochemical performance of full-cell Na-ion including NMC as cathode and HC as anode was studied in difference carbonate-based electrolytes with 2wt%FEC as additive. The cathode material was synthesized by sol-gel reaction following a calcination at 900oC for 12 hours. X-ray diffraction result of the synthesized sample indicates a layered structure with mutual O3 and P2 phase intergrowth and the dominant phase is O3. The impurity phase NiO also presents with negligeable content. In half-cell configuration with sodium metal anode, the material exhibited a typical staircase chargedischarge profile in various electrolytes. The highest capacity of 106 mAh/g with stable clycing up to 50 cycles was obtained in the electrolyte NaClO<sub>4</sub> 1 M/PC+2wt%FEC. However, this electrolyte couldn't enable the cycling the full-cell HC||NMC due to the incompatibility with HC anode. In consequence, the initial capacity of full-cell in this electrolyte was only 30 mAh/g and significantly decreased in consecutive cycles. Meanwhile, the electrolytes without PC or with low PC content tend to improve the charge/discharge capacity and the cycle life as well. Indeed, full-cell HC||NMC using NaClO<sub>4</sub> 1M/EC-DMC (1:1) + 2wt%FEC electrolyte exhibited the highest capacity of 90 mAh/g and excellent capacity retention (90% of the initial capacity) after 50 cycles. Additionally, the full-cell could deliver capacity of 55 mAh/g at high rate up to 2C.</p> 2020-10-17T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/960 Some physiological and biochemical changes of micropropagated Rhynchostylis gigantea during ex vitro acclimatization and greenhouse stages 2020-11-27T14:56:09+00:00 Cao Phi Bang phamvanphuc2308@gmail.com <p>The<em> ex vitro</em> acclimatization and greenhouse periods play a significant role for the <em>in vitro</em> originated plantlets. In these stages, the micropropagated plantlets have to rapidly adapt to environmental changes. <em>Rhynchostylis gigantea</em> is widely<em> in vitro</em> produced due to highly aesthetic and economic value. The aim of this work was to update the physiological changes of micropropagated <em>R. gigantea</em> plantlets during<em> ex vitro</em> acclimatization and greenhouse stages. The analysis results showed that leaf water content was significantly decreased at day 14 (90.36%) and day 28 (90.17%) stages but increased at day 84 (92.52%) and day 140 (92.34%) stages in compared to <em>in vitro</em> stages, day 0 (92.7%). Dry matter content was changing in the opposite direction to the leaf water content with the highest values at day 14 (9.63%) and day 28 (9.83%), respectively. The leaf transpiration rate was the highest at day zero (0.146 g/dm2/h) in compared to all other studied points. Oppositively, GPX activity was the lowest in plantlets at day zero (13.2 UI/g fresh leaf ) and the highest in planlets at day 14 (36,4 UI/g fresh leaf ). The leaf proline content was higher at day 7 and day 14 stages (132.3 and 150.8 m g/g fresh leaf, respectively) but lower at day 84 and day 140 stages (44.3 and 53.3 microgram/g fresh leaf, respectively) than at day zero (73.7 microgram/g fresh leaf ).</p> 2020-10-25T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/934 Synthesis of gold nanostar using chitosan as reductive agent by the seedless reduction method 2020-11-27T14:56:05+00:00 Khuong Quoc Vo vqkhuong@hcmus.edu.vn Hong Tong Thi phuonghong020389@gmail.com Phuong Phong Thi Nguyen ntpphong@hcmus.edu.vn Phuc Thanh Hoàng hoangthanhphuc0803@gmail.com <p>The gold nanostars (AuNS) were prepared through seedless reductive method by using the natural biodegradable polymer chitosan acting both as the stabilizing and shape-directing agent, ascorbic acid as a reducting agent. This reaction synthesis was carried out at room temperature and facile conditions. In an effort to control the size and shape of AuNS, many experimental parameters were investigated for the thorough understanding the role of chitosan in the formation of gold nanostar. In this novel method, the pH condition and appropriate stabilizer concentration were crucial factors to prepare the well-defined AuNS. The obtained AuNS were characterized by many physical-chemistry analysis method such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, dynamic light scattering (DLS), and X-Ray diffraction (XRD). The AuNS have an average size of about 55 nm and narrow size distribution when characterized by TEM images. UV-Vis spectroscopy of the gold nanoparticles colloidal solution showed the characteristic peaks at 587-700 nm, corresponding to the surface plasmon resonance of star-shaped nanostructure. The specific interactions between the functional groups of chitosan chain and the as-prepared gold nanostars are analyzed by the FT-IR spectroscopy technique. These results provided insight into the role of biopolymer as both a protecting agent and structure-directing agent. This novel method can overcome previous limitations in controlled synthesis of star-shaped gold nanoparticles such as surfactant use and complex implementation. Besides, the gold nanostars stabilized by chitosan could be a potential material in many applications in the field of biomedical medicine.</p> 2020-10-27T09:44:48+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/921 Preparation of silica/carbon composite from rice husk and its electrochemical propertives as anode material in Li-ion batteries 2020-11-27T14:56:02+00:00 Vu Tan Phat vtphat@hcmus.edu.vn Ngoc Thi Bao Nguyen nguyenbaongoc14041997@gmail.com Phung Gia Thinh phamvanphuc2308@gmail.com Tuyen Thi Kim Huynh htktuyen@hcmus.edu.vn Man Van Tran tvman@hcmus.edu.vn Phung My Loan Le lmlphung@hcmus.edu.vn <p>Rice husk is a common agricultural waste and an abundant source in Viet Nam. In terms of composition, rice husk is a silica-rich material (SiO<sub>2</sub>) so it can be used to prepare negative electrode materials for rechargeable Li-ion batteries. Recent processes of synthesizing the silica materials for the rechargeable batteries are often complex, expensive, and energy-intensive. In this study, KOH was used to treat rice husk ash to obtain SiO<sub>2</sub>/C porous composite materials. X-ray diffraction results (XRD) showed that the diffraction peak between 22<sup>o</sup> and 23<sup>o</sup> (2q ) was characterized of SiO<sub>2</sub> material, and the other peaks around 43-44<sup>o</sup> was featured of carbon material. Scanning electron microscope image (SEM) showed the porous structure with the pore size 3-5 mm.Besides, the amorphous structure with coverage layers was also confirmed through the Transmission Electron Microscope (TEM) images. Preliminary electrochemical results demonstratedthat Li-ion coin cell using the SiO<sub>2</sub>/C anode material exhibited a high capacity of 1200 mAh/g at a discharge current of 1.0 A/g and maintained 1000 mAh/g after 100 cycles. SiO<sub>2</sub>/C materials prepared from rice husks were highly promising for battery application thanks to their low cost, stable performance, environmental friendliness, and easy expansion for production scale.</p> 2020-10-27T10:06:39+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/863 Seasonal variation of zooplankton in Ba Lai river, Ben Tre province 2020-11-27T14:55:56+00:00 Nhi Nguyen Y Ha hanguyenynhi@gmail.com My Ngoc Diem Tran tndmy@hcmus.edu.vn <p>The purpose of research is studying the variation of zooplankton community in Ba Lai river in Ben Tre province. Research was conducted in 2 seasons: rainy season (December, 2017) and dry season (March, 2018). There were 7 sampling points in Ba Lai river, Ben Tre province. Our study recorded 95 taxa zooplankton belong to 56 genera, 39 families, 12 orders, 8 classes and 5 phylums. Generally, Rotifers had highest munbers of species among 2 seasons. Rotifers were dominant in density and species composition at all sampling points in the rainy season. Copepods were dominant in density and species composition in the dry season. There were some marine species present at sampling points during the dry season. In addition, the Bray - Curtis analysis showed that the similarity of the zooplankton communities between rainy season and dry season at sampling points wasnot high. This suggests that there was a shift in the structure of the zooplankton community between rainy season and dry season. These are proof to prove the salinity rising in Ba Lai river in dry season. Although there is an irrigation dam to prevent the infiltration of salt water, but the infiltration of salt water is happening. A solution to preserve fresh water to provide local people in dry season is necessary.</p> 2020-11-03T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/915 The Synthesis of silica nanoparticles from Vietnamese rice husk - Application for adsorption of heavy metals in industrial wastewater 2020-11-27T14:55:51+00:00 Đào Thi Băng Tâm dtbtam@hcmus.edu.vn Nguyễn Trung Độ ntdo@hcmus.edu.vn Lưu Kiến Quốc lkquoc@hcmus.edu.vn Hà Thúc Chí Nhân htcnhan@hcmus.edu.vn <p>Heavy metals are known to be toxic, even at low content (ppm), for living organisms<sup>[1,2]</sup>. The presence of heavy metals and other pollutants in water continues to be a major concern and the removal of such contaminants is considered as an important solution for environmental remediation<sup>[3,4]</sup>. In this paper, we study the ability adsorption of &nbsp;Pb<sup>2+</sup> and Cd<sup>2+</sup> heavy ionic metal on silica nanomaterials which was extracted and purified from Vietnamese rice husk. The structure of the materials was investigated by X-ray diffraction (XRD) and FT-IR spectroscopy. By Adsorption Atomic Spectroscopy (AAS) analysis, the results have demonstrated the time taken for attaining equilibrium adsorption is about 1.5 hours for both cases, and the adsorption capacity of Pb<sup>2+</sup> and Cd<sup>2+</sup> on silica are 21 and 24 mg/L, respectively.</p> 2020-11-03T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/951 Design of a monitoring and control system for Aquaponics based on Iot technology 2020-11-27T14:55:42+00:00 Nhan Chi Nguyen ncnhan@hcmus.edu.vn Khang Phuoc Hoang Nguyen nphkhang@hcmus.edu.vn Quan Hoang Nguyen nhquan@hcmus.edu.vn Hieu Van Nguyen nvhieu@hcmus.edu.vn Huy Thanh Ho hothuy@hcmus.edu.vn <p>This paper presents the design of environmental monitoring and control system in aquaponics based on Internet of Things (IoT) technology. This system allows users to monitor and control the operation of devices through the application on smartphones, including: 3 water pumps, 3 air pumps, pH sensor, dissolved oxygen (DO) sensor, temperature sensor and humidity sensor, exhaust fan and misting. These devices are monitored and controlled in two modes: automatic and manual control. For 3 pumps and 3 air pumps, in automatic mode, allows the user to set the pump time between water pumps and between air pumps. In manual control mode, allows the user to control water pumps and air pumps by the push of a button on a smartphone application. Monitor pH, DO and allows the user to set the pH threshold and DO threshold to give an alert when the pH and DO exceed the threshold. Monitor the parameters of temperature, humidity in the membrane house and allow setting the temperature threshold and humidity threshold to control the exhaust fan and misting respectively when the temperature and humidity exceed the threshold. This system tested at aquaponics farm - Dong Thap Aqua. The results show that this system is working reliably and promising which brings significantly benefits to aquaponics. Besides, it also contributes to improve production efficiency and sustainable development of green agriculture.</p> 2020-11-09T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/929 Transgenic Drosophila melanogaster model of metabolic disorders 2020-11-27T14:55:45+00:00 Thao Thi Phuong Dang thaodp@hcmus.edu.vn Linh My Dao dmlinh@hcmus.edu.vn Anh Man Huynh mrmananh@gmail.com Dan Thi Hanh Vo hanhdanvlg@gmail.com <p>Metabolic syndrome is a collection of disorders related to metabolisms such as obesity, lipid disorders, hyper/hypoglycemia, ... Metabolic syndrome can lead to cardiovascular diseases, strokes, and diabetes - the leading death causes in the world. In many cases, metabolic disorders are original by the redundant/ reduction of insulin- the most important hormone in metabolism regulation. Both of them are involved in beta-cells dysfunction. Many mechanisms related to this phenomenon has been approved, notably mitochondrial dysfunction and the Ubiquitin proteasome system impairment. UCH-L1 is a protein belonging to the Ubiquitin proteasome system and highly expressed in beta cells. Previous studies reported that decrease UCH-L1 function can alter metabolism and lead to b cell apoptosis under various nutritional conditions, however, the mechanism has not been clarified. In this study, we proposed a Drosophila melanogaster model that expresses many symptoms of metabolic syndrome, by knocking down dUCH (Drosophila homolog of UCH-L1) specifically in Insulin-producing cells. Our fruit fly model had abnormal metabolism, physiology, loss of insulinproducing cells, and mitochondria over-workload, similar to metabolic syndrome in humans. These results suggested that this model is suitable for further studies on the role of UCH-L1 in b cells, as well as a potential model in metabolism diseases' drug screening.</p> 2020-11-09T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/860 An algorithms to improve the energy resolution of two-step cascade spectrum 2020-11-27T14:55:37+00:00 Nguyen Ngoc Anh ngocanh8999@gmail.com Nguyen Xuan Hai xuannguyennri@gmail.com Hồ Hữu Thắng thanghonds@gmail.com Phan Bao Quoc Hieu pbqhieu@gmail.com Truong Van Minh truongminhdnu@gmail.com <p>The present paper proposes an algorithm to improve the energy resolution of two-step cascade spectrum. The energy resolution plays an important role in the domain of gamma spectrum analysis. The better the energy resolution is, the better the ability of peak resolving is. The algorithm is constructed based on an analyze of energy resolution of the summation amplitude of coincident pulses spectrometer using the analogue technique. The algorithm proposed has been tested on some two-step cascade spectra of <sup>164</sup>Dy nucleus obtained from the (n, ) reaction experiment using the gamma – gamma coincidence spectrometer at Dalat Nuclear Research Institute. Two-step cascade spectra corresponding to the cascade decays from the compound state to final states whose energies are 0, 74, and 242 keV have been evaluated. The results obtained show that the energy resolution of the two-step cascade spectrum has been reduced by 1.05 to 2.04 times within the energy range of 586 to 6830 keV. Our algorithm can therefore be applied to improve the ability of peak deconvolution, the accuracy, and the realibility in analyzing two-step cascade spectra.</p> 2020-11-13T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/891 The effect of the blue light on the pericarp cell growth and lycopene content of cherry tomato (Solanum lycopersicum var. cerasiforme) fruit 2020-11-27T14:55:34+00:00 Dien Thi Kieu Pham kieudien93@gmail.com Kiet Thuong Do dtkiet@hcmus.edu.vn Sanh Du Nguyen ndsanh@hcmus.edu.vn <p>The cherry tomato fruit size depends on the growth of the pericarp which is parenchymal cells. The blue light stimulates the expansion of cotyledon cells, hypocotyl cells and leaf cells. In this study, the cherry tomato fruit was used as a material to investigate the effects of the blue light on the pericarp cells growth in fruit growth stage and lycopene accumulation in fruit growth and ripening stage. After 7 days of the blue light (440, 450 or 460 nm) treatment, pericarp cells growth and physiological, biochemical changes of the pericarp cells of 7-day-old fruit pericarp piece in vitro were analyzed. The lycopene content and some organic compound contents of 42-day-old postharvest fruits treated by the blue light similarly in 7 days and 7, 21-day-old fruit wrapped with blue filter (440-510 nm filtered) in 7 days were measured. The results showed that the 450 nm wavelength blue light the increased pericarp thickness of 7-day-old fruits through the increasement of the pericarp cell diameter. The 460 nm wavelength blue light the increased lycopene content of 42-day-old postharvest fruits. The blue filter treatment increased the sugar total content of 7- day-old fruits and increased the lycopene content of 21-day-old fruits.</p> 2020-11-13T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/866 Using free-living nematode communities as biological monitoring of environmental quality status in Ben Tre city 2020-11-27T14:55:07+00:00 Thai Thanh Tran thanhthai.bentrect@gmail.com Nguyen Le Que Lam leopique62@gmail.com Nguyen Thi My Yen myyenitb@gmail.com Pham Thanh Luu thanhluupham@gmail.com Tran Thi Hoang Yen tthyen95@gmail.com Nguyen Thi Huynh huynhnguyen.821992@gmail.com Lam Van Tan lvtan.skhcn@bentre.gov.vn Ngo Xuan Quang ngoxuanq@gmail.com <p>Nematode communities were used as a tool to assess the environmental quality status of sediment of the water bodies in Ben Tre city. Eight locations in the main canals and river in the city were surveyed during the rainy season (September). The study recorded 51 genera belonging to 33 families, 10 orders (Araeolaimida, Chromadorida, Desmodorida, Dorylaimida, Enoplida, Monhysterida, Mononchida, Plectida, Rhabditida, and Triplonchida), 2 classes (Chromadorea and Enoplia). The density of nematode communities at most survey locations is quite high, ranging from 29.88 +/- 38.01 to 1172.08 +/- 659.74 individuals/10 cm<sup>2</sup>. However, the biodiversity is quite low, species richness index (S) ranged from 5.33 1.15 to 18.33 4.72, and Shannon diversity index (H') from 1.28 +/- 0.12 to 3.19 +/- 0.50 and Pielou's evenness index (J') from 0.47 +/- 0.04 to 0.93 +/- 0.04. The Maturity Index (MI) of nematode communities was applied to assess the environmental quality status of sediment. The results showed that the environmental quality status of sediment recorded disturbances, classified as bad to moderate. The colonizer-persister (c-p) combined with the MI is a potential tool in biological monitoring of environmental quality status. However, to increase the reliability of evaluation conclusions, the combination of MI and biological indicators as well as physical-chemical parameters is necessary.</p> 2020-11-16T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/652 Phonon investigation on the interaction of hydrogen on the missing row Pt (110)-(1x2) surface 2020-11-27T14:54:48+00:00 Hoa Van Nguyen nvhoa.sdh20@hcmut.edu.vn Phi Minh Nguyen 1512425@hcmut.edu.vn Thien Ngoc Nguyen thien08kvl@gmail.com Dao Minh Chau minhdao003@gmail.com Hanh Thi Thu Tran thuhanhsp@hcmut.edu.vn <p>The phonon calculations of hydrogen when adsorbed on the missing row Pt(110)-(1x2) surface using the Ultrahigh Vacuum (UHV) model were studied. The calculations were based on a combination of Density Functional Theory (DFT) and the approximation of hydrogen vibrations on the surface. The harmonic vibration of H on the Pt surface was used for the calculation in this study. At the hydrogen coverage of 1ML for the model surface (when H completely covering the Pt surface), the interaction formed at the edge of the first layer (short bridge - R) was the most stable. The less stable positions were recorded as the bridge position between two atoms on a horizontal row in the second layer (trough - T), the top position of the second surface layer - fcc (F), the bridge position of the second surface layer - hcp (F'), and the least stable position was the top position of the first layer (T'). When accounting the quantum calculation for the model, the adsorption energy of hydrogen at the short bridge position increased by 90 meV, and the stable adsorption order of hydrogen changed with the most stable positions ware R, T, T', F', F respectively. This demonstratesd the significant influence of quantum effects on the adsorption model.</p> 2020-11-21T00:00:00+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/911 Effect of the pyrolysis temperature after hydrothermal reaction on the structure of electrode material LiFexCo1􀀀xPO4 (0.1 x 0.5) and electrochemical evaluation of this material in Li-ion half-cell 2020-11-27T14:55:29+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_911_cover_en_US.png Quang Đại Tran trandaiquang2015@gmail.com Hoang Van Nguyen hoangkhtn09@gmail.com Mẫn Văn Trần tvman@hcmus.edu.vn Phụng Mỹ Loan Lê lmlphung@hcmus.edu.vn <p>High voltage cathode LiCoPO4 has been taken great interest for high power Li-ion batteries (LIBs). Though Co enhance the cyclability, capacity of materials, Co concentration should be reduced in electrode materials due to its high cost and toxic. In this work, the solvo-thermal reaction following by pyrolysis in inert Ar was investigated to synthesize the electrode materials LiFe<sub>x</sub>Co<sub>1-x</sub>PO<sub>4</sub> (0.1 &lt;= x &lt;= 0.5) for LIBs. The structure of the materials after calcinated at 600 oC, 700 oC and 800 oC was analyzed by X-ray diffraction (XRD). The results indicated that the olivine structure was obtained for all Fe contents, except for x = 0.5. At the content of 0.1 and 0.5, the intensity of impurity peaks in the samples increased with the pyrolysis temperature. Meanwhile, other samples did not display the obvious change of olivine structure. Electrochemical properties of the materials were evaluated via cyclic voltammetry (CV) and Galvanostatic charging-discharging. CV curves of the samples with Fe content of 0.2x0.4 all displayed high intensity and reversible redox peak of Co<sup>3+</sup>/Co<sup>2+</sup> locating at 4.8 V and another peak of Fe<sup>3+</sup>/Fe<sup>2+</sup> locating at 3.5 V. As the Fe content increased, the former peaks decreased while the latter increased due to the change of active species concentrations. Unfortunately, the specific capacities obtained for Fe-substituted materials were lower than the pristine material (70 mAh/g versus 120 mAh/g) and gradually declined during cycling. The results could be due to the electrolyte decomposition in the first charging. However, the sample with x = 0.1 exhibited the best performance with discharge capacity of 70 mAh/g and 73% capacity retention obtained after 25 cycles, which was better than the sample with x = 0.2 and unsubstituted sample.</p> 2020-11-13T09:47:04+00:00 ##submission.copyrightStatement## http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/927 Study of Curcumin Adsorption of Nano Fe-based Metal-Organic Framework 2020-11-27T14:55:18+00:00 http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_927_cover_en_US.png Trang Thị Thu Nguyễn ntttrang@inomar.edu.vn Ý Thị Đặng dty@inomar.edu.vn Linh Hồ Thùy Nguyễn nhtlinh@inomar.edu.vn Hạnh Thị Kiều Tạ ttkhanh@hcmus.edu.vn Thắng Bách Phan pbthang@inomar.edu.vn Tân Lê Hoàng Đoàn dlhtan@inomar.edu.vn <p>Highly porous and biocompatible nano metal-organic framework materials (NMOF) are increasingly being applied in biomedical fields, especially as pharmaceutical adsorbent materials. Curcumin, found in turmeric, is a widely common herb in Eastern which has recently used in many applications in supporting cancer treatment. In the synthesis of MOF materials, the use of surfactants allows to control the morphology, the process of crystal formation and development and particle size of the material. In this research, MIL-100 (Fe) nanomaterials were successfully synthesized at room temperature in the presence of polyvinylpyrrolidone surfactant (PVP) to control the nanoparticle size about 50 nm in size. The synthesized MOF structure and properties were analyzed by using characterization techniques, including powder X-ray diffraction (PXRD), fourier-transform infrared (FT-IR), thermal gravimetric analyses (TGA) and nitrogen isothermal adsorption-desorption at 77 K. The characterization results showed that MIL-100 (Fe) nanomaterials have high crystallinity, large surface area, and highly thermal stability. However, its particle size is very small, only about 50 nm. Curcumin adsorption studies exhibited that this material had the ability to adsorb curcumin with an adsorption capacity up to 64.36 mg g<sup>-1</sup>. Kinetic and mechanism studies revealed that curcumin adsorption followed the pseudo-second model. In addition, thermodynamic studies proved that this was a spontaneous and exothermic adsorption process.</p> 2020-11-13T09:56:54+00:00 ##submission.copyrightStatement##