VNUHCM Journal of Natural Sciences 2022-11-18T21:12:16+00:00 Phuc Van Pham Open Journal Systems Effects of nitrogen on growth and nitrate accumulation in mustard green (Brassica juncea L. ) in the hydroponic system 2022-08-21T05:00:27+00:00 Tran Thi Thanh Hien Tran Thanh Thang <p>Nitrate content (NO3-) is one of the important indicators to assess the quality of leafy vegetables. Many studies have shown that vegetables in local markets containing high levels of nitrate that induce harmful effects on human health. In Vietnam, publications on the correlation between NO3-/+NH4 ratio and the nitrate accumulation are limited. Mustard green (Brassica juncea L.) is a popular vegetable and has a high nutrient (rich in fiber and micronutrients). However, the effect of nitrogen on the nitrate accumulation by hydroponic has not been elucidated. In this study, mustard green was grown in four media with different NO3-/+NH4 ratios (2/1; 1.5/1; 3/1, and 4/0) in the hydroponic reflux system. Results showed that the nitrogen requirement of mustard green depended on growth stages. Mustard green needed a low NO3-/+NH4 ratio at the slow growth stage (seedlings) and a high NO3-/+NH4 ratio at the fast one. In addition, the increase of the nitrate content also improved the chlorophyll content in the leaves. The complete removal of +NH4 in the medium stimulated the nitrate accumulation in leaves. The study showed that the suitable hydroponic medium for mustard green was MS medium supplemented with twice KNO3. The KNO3 addition in the hydroponic medium increased the chlorophyll content, the fresh weight, and ensured the content of nitrate (417.59 ± 10.51 mg/kg) within the allowable limits (&lt; 500 mg/kg).</p> 2022-08-21T00:00:00+00:00 ##submission.copyrightStatement## Six flavonoids from the ethyl acetate extract of the pericarp of Garcinia schomburgkiana 2022-08-21T05:26:29+00:00 Trí Hữu Nguyễn Tuyết Thị Ánh Nguyễn Lien Thi-My Do <p>Garcinia is a genus of Clusiaceae, distributed throughout tropical Asia, Africa, New Caledonia, Polynesia, and Brazil. In traditional medicine, the fruits of Garcinia have been utilized in infusions for treating wounds, ulcers, and dysentery. Extracts of the pericarp and seeds of Garcinia have demonstrated antioxidant, anti-inflammatory, leishmanicidal, and antiprotozoal activities. Garcinia plants contained a broad range of biologically active metabolites which, in the last few decades, have received considerable attention due to the chemical compositions of their extracts, with compounds possessing beneficial effects in several diseases. These species provide a rich natural source of bioactive compounds with relevant therapeutic properties and anti-inflammatory effects, such as flavonoid, xanthone, biflavonoid, biphenyl derivaties, and benzophenone. This paper demonstrated the relevance of the genus as a rich source of compounds with valuable therapeutic properties, with potential use in the prevention and treatment of nontransmissible chronic diseases. Phytochemical investigation on the fraction EA4 from the ethyl acetate extract of the pericarp Garcinia schomburgkianna led to the isolation of six flavonoid compounds such as quercetin (1), kaempferol (2), luteolin (3), cirsiliol (4), quercetin 3-O-β-D-glucopyranoside or isoquercetin (5) and quercetin 3-O-α-L-rhamnopyranoside (6). Their chemical structures were elucidated by 1D, 2D–NMR as well as compared with the literatures. Compounds (1), (3), (4), (5), (6). were isolated for the first time from the species Garcinia schomburgkiana collected at Quang Binh province, Vietnam.</p> 2022-08-21T00:00:00+00:00 ##submission.copyrightStatement## Aristolactame and aporphine alkaloid from the ethyl acetate extract of stems Melodorum fruticosum L. 2022-08-21T05:35:55+00:00 Hương Thị Mỹ Nguyễn Liên Thị Mỹ Đỗ <p>Melodorum fruticosum (Annonaceae), a shrub with fragrant yellow flowers, distributed in South East Asia, more specifically indigenous to Thailand, Laos, Cambodia, and Vietnam. In Vietnam, M. fruticosum has been used as folk medicine remedies for the treatment of digestive diseases, abdominal dyspepsia in women after giving birth. This plant has been used as a tonic, a mild cardiac stimulant, antipyretics and as a hematinic to resolve dizziness by Thai people. The essential oil of M. fruticosum flowers is used in aromatherapy and as traditional medicines in Thailand. Its flowers and barks have been reported to have antifungal, antioxidant, and cytotoxic activities. Phytochemical investigation on the fractions EA.3 and EA.4 from the ethyl acetate extract of stem of M. fruticosum led to the isolation of five alkaloids including aristolactame AII (1), goniopedalin (2), piperolactame C (3), 10-amino-3,6-dihydroxy-2,4-dimethoxyphenanthrene-1-carboxylic acid (4) and noraristolodione (5). Their chemical structures were elucidated by 1D and 2D–NMR, ESI-MS as well as compared with data in the literatures. All these compounds were isolated for the first time from the M. fruticosum collected at Di Linh district, Lam Dong province, Vietnam. All isolated were evaluated for their cytotoxicity against KB, Hep-G2, and MCF-7 cell lines. Among them, compound (2) showed weak cytotoxicity against the tested cell lines.</p> 2022-08-21T00:00:00+00:00 ##submission.copyrightStatement## Green synthesis of well-dissolved high-stable silver nanoparticles using hydroxypropylmethyl cellulose as a protective agent 2022-11-15T20:59:16+00:00 Hà Thị Nguyễn Ngọc Hoa Thị Lê Bích Tuyền Thị Nguyễn Kim Lộc Thị Nguyễn Ngọc Uyên Thái Nguyễn An Nang Vu <p>This paper presented the synthesis of Ag nanoparticles (Ag NPs) by the chemical reduction method which is simple and environmentally friendly. Silver nitrate, hydroxypropylmethyl cellulose (HPMC), and glucose were used as silver precursors, protective agents, and reducing agents, respectively. The effects of AgNO3 concentration, glucose concentration, HPMC content, reaction time, and reaction temperature on the formation of Ag NPs were investigated. The properties of Ag NPs were analyzed by transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectroscopy, and X-ray diffraction (XRD). The results indicated that when the HPMC content was 0.01%, AgNO3 concentration was 0.05 M and glucose reducing agent concentration was 0.4%, the best reaction occurred in 9 hours at 90oC. The Ag NPs prepared under HPMC protection possessed a face-centered cubic crystal structure (FCC), a spherical shape having average sizes in the range of 8 ‒ 12 nm. The Ag colloidal solution had a suitable zeta potential (-37.21 mV) to maintain the stability and to avoid the agglomeration of Ag NPs. In addition,the paper proposed a method to indirectly determine the Ag NPs content through the separation of Ag NPs from the colloidal solution by coagulation, using the electrolyte Al(NO3)3.9H2O.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Synthesis of carbon nanofibers from electrospun polyvinylidene fluoride nanofibers for cathode electrodes in Li-O2 batteries 2022-11-15T21:14:32+00:00 Manh Dang Le Phuong Hoai Pham Hieu Trung Bui <p>PVDF nanofibers were fabricated by the electrospinning method from polyvinylidene fluoride (PVDF) solutions in mixture of DMF and acetone solvents. PVDF fibers were then converted to CNF fibers through the low-temperature chemical stabilization ("dehydrofluorination") before carbonization at 800°C. The free-standing, perforated features of the CNF-based PVDF enabled the CNF to be directly applied as an air cathode in a LOB just after drying, without requiring additional conducting additives or polymeric binders. The interconnected pores between the individual CNFs were estimated to be 2‒4 µm. This could prevent the electrode from clogging when the discharge product was formed. With the interstitial voids and a large surface area, the CNF electrode synthesized from polymer PVDF had a capacity of 2,600 mAh/g with a current density of 200 mA/g. Moreover, CNF fibers, synthesized from electrospun PVDF nanofibers containing C‒F bonds, could improve the electrode conductivity, forming Li2O2 discharge products with less crystalline properties, leading to overpotential reduction during a discharge. This contributed to the longer cycle life of Li-O2 batteries using the CNF synthesized from electrospun PVDF nanofibers electrode (97 cycles) compared to the one synthesized from electrospun PAN nanofibers electrode (73 cycles) at a limited capacity of 1,000 mA/h and a current density of 200 mA/g. Their structure and morphology were evaluated by Scanning Electron Microscopy, Fourier-transform infrared Spectroscopy, Energy Dispersive X-ray Spectroscopy, X-ray diffraction, and Raman Spectroscopy.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Studying the appropriate reaction conditions for the high yield controlled synthesis of gold nanostars by the seed-mediated method 2022-11-16T09:38:52+00:00 Anh Thu Nguyen Viet Ha Thi Le Sy Van Vu Bich Thao Thi Nguyen Khuong Vo Quoc Anh Thi Ngoc Quang <p>In this work, the gold nanostars (AuNS) were highly efficient in synthesis through the seed-mediate method using the surfactant cetyltrimethylammonium bromide (CTAB) and the reductant ascorbic acid. Significantly, the length of branches on the AuNS was controlled by governing the reaction composition. The effects of AgNO3 volume and CTAB concentration on the formation of AuNS were systematically investigated for clarifying their role in the growth of gold nanocrystal; thereby controlling the shape, number, and length of branches on the star-like nanoparticles. The UV-Vis analysis and scanning electron microscopic images exhibited that the AuNS were formed with the prepared condition with AgNO3 0.05 mM, 0,10 M CTAB; and the desired lengths of branches on AuNS were successfully adjusted. The physical chemistry properties of formed AuNS were further characterized through Ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDS), and zeta potential (ZP), X-Ray diffraction, and selected area electron diffraction (SAED). The UV-Vis results show the surface plasmon resonance (SPR) peaks around the wavelength of 700-750 nm, indicating the formation of AuNS. The TEM and SEM images further clarify the prediction of the formation of AuNS with long and shaped branches. DLS results were performed that the synthesized AuNSs have an average size of 13 nm. In addition, the XRD, EDS, and zeta potential also provide a more understanding insight into the formation mechanism of AuNSs. The yield of the synthesized process of AuNS was significantly improved to 96,82 %, based on ICP-MS methods. This nanomaterial is feasible for many application fields, including biosensors, catalysts, and drug delivery.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Determination for 3D sedimentary basin depths from gravity anomaly data using steepest descent method 2022-11-16T09:41:25+00:00 Tin Quoc Chanh Duong Toan Phuoc Luong <p>In solving the gravity exploration inverse problems, determining the depth of the sedimentary basin played an important role in the petroleum exploration. In this paper, the depth to the basement of 3D sedimentary basin was calculated from the gravity anomaly using the steepest descent method. This method allowed minimizing the objective function based on the first derivative and adjusting the step length by the iterative method; using the variable is the depth of adjacent rectangular prism in the x, y directions with parabolic function between density contrast and the depth. The parameters in the parabolic function were determined by the nonlinear regression method based on the information of deep borehole in the Mekong Delta. This parabolic function was used to calculate the theoretical gravity anomaly for the sedimentary basin and solve the 3D inverse gravity problem on the model and on the real data. The used objective function was the mean square error function between the measured gravity anomaly and the calculated anomaly. The proposed method was tested on the model, showing that the calculated sedimentary basin depth almost coincides with the original model depth; then the method was applied to calculate the depth of 3D sedimentary basin from the local gravity anomaly in Bac Lieu province. The analysis results were consistent with previous publications, but the calculation time was significantly shortened, so this method can be extended to analyze data on a large area.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Determination of the bacteria present along with the tuberous root formation in yacon - Smallanthus sonchifolius 2022-11-16T09:44:02+00:00 Vân Thị Thu Bùi Như Ngọc Quỳnh Nguyễn Hiền Thị Thanh Trần Hương Thị Lan Vũ <p>Yacon (Smallanthus sonchifolius), a plant traditionally grown in the Northern and Central Andes, is recently cultivated in Vietnam. The edible storage roots of yacon contain a large amount of carbohydrate during the form of indigestible fructooligosaccharide (FOS), which functions as a prebiotic and gives positive effect during the treatment of obesity, diabetes, and colorectal cancer. Thus, yacon root is expected to be a good dietary supplement for patients with these diseases. There has been limited research about the impacts of microorganisms on the tuberous root formation of yacon. Therefore, this paper presents the enumeration of aerobic bacteria in the root area at the two growing stages, before and in the early stage of the tuberous root formation, of yacon by MPN (Most Probable Number) method. The obtained results show a significant change on the amount carbohydrate metabolism bacteria presence in yacon roots between the two growing stages. Besides, there are more carbohydrate metabolism bacteria (9,3 x 105 MPN/mL) in tuberous root than protein metabolism bacteria (9,3x103 MPN/mL). The isolation of aerial bacteria from yacon roots found 22 strains, which are assigned into the 10 genera including Burkholderia, Caulobacter, Myroides, Pantoea, Pseudomonas, Stenotrophomonas, Kosakonia, Rhizobium, Enterobacter, and Klebsiella based on the phylogentic analysis of the so-called 800R 16S rRNA gene sequences. The appearance of those genera in difference parts of yacon root is not the same. The presence of difference genera is also shown in the roots at the two growing stages.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Synthesis, investigation of the properties and evaluation the stability of the mix halogen perovskite (Cl, Br, I) and fabrication of perovskite solar cells 2022-11-16T22:57:51+00:00 Thi Thanh Nguyen Ho Minh Hien Tran Nguyen Huynh Le Thanh Viet Hai Le Thai Hoang Nguyen <p>Perovskite CH3NH3PbI3 has been attracted significant attention because of its high absorption coefficient, the ideal band gap energy (Eg =1.5 eV) and the low cost of synthesis. However, CH3NH3PbI3 had an intrinsic issue regarding the long-term stability due to the unstable bond of Pb‒I. In addition, the CH3NH3PbI3 cubic structure had easily been occurred in the phase transition. The chloride or bromide ion, a high electronegativity, was used to exchange for I- in CH3NH3PbI3 to create the mixed halide perovskites, CH3NH3PbI3-xBrx (x = 0.5‒1.5) and CH3NH3PbI1,8Cl1,2. The structure of materials was identified by XRD. The stability of CH3NH3PbI3-xBrx or CH3NH3PbI3-xClx was investigated during 290 hours in an environmental chamber (80 % humidity, 40 °C). The band gap of perovskites could be tunned by controlling the Cl-, Br- or I- ratio. The result revealed that the half‒life of CH3NH3PbI3-xBrx and CH3NH3PbI3-xClx were higher from 2 to 4 times than that of CH3NH3PbI3. Perovskite solar cells based-on CH3NH3PbI2,5Br0,5 and CH3NH3PbI1,8Cl1,2 were fabricated by using spin-dip coating 2 steps process possessing the maximum efficiency of 11.4 % (J<em><sub>sc</sub></em> = 0.99<sup>-2</sup>, V<em><sub>oc</sub></em> = 1.05 V) and 12.3 % (J<em><sub>sc</sub></em> = 1.14<sup>-2</sup>, V<em><sub>oc</sub> </em>= 1.01 V) under AM 1.5 simulated sunlight of 1,000 W.m<sup>-2</sup> light intensity</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Synthesis of LiFePO4/C as the positive material for LiFePO4/GRAPHITE Lithium‒Ion batteries 2022-11-16T22:59:49+00:00 Thư Minh Nguyễn Phước Hữu Lê Liêm Thanh Phạm Khoa Anh Nguyễn Huỳnh Nhân Thanh Trần Mẫn Văn Trần Phụng Mỹ Loan Lê Ngân Huệ Đái <p>This paper presented the synthesis of carbon coated LiFePO4 (LFP/C) materials by hydrothermal method with glucose as a carbon source at two temperatures of 700oC (LFP700/C) and 800oC (LFP800/C). According to X-ray diffraction analysis, the material's structure was monophasic and devoid of impurities. The scanning electron microscopy revealed that the morphology of the composites at 700oC and 800oC was elongated and irregularly shaped-crystal with the particle size of 100‒500 nm. The Cycling Voltammetry and Galvanostatic Cycling with Potential Limitation were used to examine the electrochemical characteristics of LFP/C materials. After 50 cycles, the specific capacities of the LFP700/C and LFP800/C in 1.0 M LiPF6 EC: DMC: DEC (1:1:1, v:v:v) were 115 mAh.g-1 and 136 mAh.g-1, respectively, and the Coulombic efficiency was around 97%. The diffusion coefficient of Li+ reached 7.161.10-12 cm2.s-1 (LFP700/C) and 2.489.10-10 cm2.s-1 (LFP800/C) which was higher than that of the raw LFP sample (10-14‒10-13 cm2.s-1). The Full-cell LFP800/Graphite was investigated with four N/P ratios of 1.0, 1.1, 1.2, and 1.3. The charge‒discharge results showed that the full-cell of LFP800/Graphite with N/P ratio of 1.2 in 1.0 M LiPF6 EC: DMC: DEC (1:1:1, v:v:v) exhibited an excellent cyclability at C/10. The capacity of this full cell reached 112 mAh.g-1 in the first cycle and remained at 80% capacity after 50 cycles.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## In vitro antithrombogenicity and endothelialization evaluation of heparin immobilized bovine pericardial scaffold 2022-11-18T08:23:28+00:00 My Thi Ngoc Nguyen Nghia Hieu Thi Phan Hoang Minh Lam Ha Bao Le Tran <p>Thrombogenicity is one of the challenges when using membrane grafts in cardiovascular surgery. Therefore, this paper presented the fabrication of bovine pericardial scaffold immobilized with heparin in order to improve its antithrombogenicity for the application in the cardiovascular field. Heparin was immobilized on the scaffolds by the layer-by-layer method, based on the interaction of heparin and dihydroxy-iron (DHI). The structure, biochemistry, anticoagulation, and ability to support the endothelial cell attachment were evaluated to determine the effectiveness of the heparin immobilization. Histology staining and scanning electron microscopy images revealed the presence of heparin on the bovine pericardial scaffolds. The quantitative result demonstrated that the layer-by-layer method significantly increased the heparin content on bovine pericardial scaffolds. The heparin-immobilized scaffolds performed a good antithrombogenicity after direct incubation in the whole blood samples. This antithrombogenicity was maintained after 30 days of testing. Additionally, the scaffolds were shown to cause no cytotoxicity and support endothelial cell adhesion after 48 hours. These results indicated the potential of heparin-immobilized bovine pericardial scaffolds for the application in cardiovascular transplantation.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Montmorillonite/TiO2 nanotubes could enhance the photocatalytic activity of rhodamine B degradation in the UVC region 2022-11-18T08:32:13+00:00 Đào Thi Băng Tâm Loan Thi Thu Ha Do Trung Nguyen Truong Huu Nguyen Nhien Hon Le Chi-Nhan Ha-Thuc <p>MMT/TiO2-NTs nanocomposite materials were prepared by a simple wet agitation method at room temperature from TiO2 nanotubes and montmorillonite (MMT). The synthesized MMT/TiO2-NTs samples were used as a catalyst for the photocatalytic degradation of rhodamine B (RhB) under a UVC light source (15 W, 254 nm). MMT was purified from bentonite clay (Lam Dong, Vietnam). MMT after purification possessed a characteristic lattice surface (001) at an angle of 2 = 6.1°. The adsorption capacity and the basal spacing of MMT were 70 mg/g and 14.48 Å, respectively. The TiO2 nanotubes (TiO2-NTs) were synthesized by the hydrothermal method. TiO2-NTs possessed a polycrystalline structure consisting of two phases, anatase and rutile. The average diameter and the length of the TiO2-NTs were 5 nm and 110 nm, respectively. The results on the composition, surface morphology, crystal structure, bonding vibration and photocatalytic efficiency characteristics showed that after modification into MMT, TiO2-NTs were immobilized and randomly distributed on the surface or incorporated in the clay sheets of MMT to form a pillared interlayer clay (PILC) structure. Because MMT possessed good adsorption properties, MMT would act as an adsorption center to capture RhB molecules in clay layers. MMT also prevented the recombination of TiO2 by trapping the photogenerated e into the vacant d orbitals of the metallic elements present in the MMT. Then, the •OH or •O2 radicals generated from the TiO2 photocatalytic reaction would easily react with the RhB molecules and decomposed them. The photocatalytic efficiency of 10 ppm RhB degradation of MMT/TiO2-NTs was 82% when excited by a UVC source for 210 min.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Preparation of rGO-Cu2S for quantum dot sensitized solar cells application and investigation of its properties 2022-11-18T08:43:08+00:00 Phuong Thu Thi Nguyen Thang Van Bui Ha Thanh Tung <p>This paper presents the results of fabrication of reduced graphene oxide - Cu2S cathode to replace the Pt, CuS, PbS and Cu2S cathode electrodes in an quantum dot sensitized solar cell. The rGO-Cu2S material was fabricated by hydrolysis and printed onto the surface of the FTO substrate with a proportional change in the mass of graphene oxide and Cu2S nano, and then the film was calcined at 350 oC. The electrode structure after calcination was analyzed by X-ray diffraction spectroscopy, the particle size was determined by transmission electron microscopy, and the surface morphology was determined by scanning electron microscopy, semiconductor type is determined by Mott-Schottky measurement and the redox ability of the electrode in the polysulfide electrolyte system is evaluated by electrochemical equipment. The results show that the performance of the rGO-Cu2S cathode is better than that of the Cu2S electrode, which has been proven through the C-V measurement. This is a very positive signal for the team to continue researching to fabricate quantum dot sensitized solar cells and determining photovoltaic efficiency in further studies.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Chemical constituents of the aerial parts Helicteres hirsuta Lour (Malvaceae) 2022-11-18T08:56:04+00:00 Thao Ly Thi Nguyen Hoai Tu Tran Ngoc Mai Tran Hoang Quan Pham Phu Hoang Dang Thanh Truc Thi Duong Nhan Trung Nguyen <p>This paper reported the isolation of chemical constituents from the chloroform extract of aerial parts of Helicteres hirsuta Lour (Malvaceae) and isolated compounds were evaluated for their α-glucosidase inhibitory. This work aimed to discover effective α-glucosidase inhibitors for scientific evidence in using medicinal plants for diabetic treatment in Vietnamese traditional medicines as well as developing drugs for diabetic treatment. From the CHCl3-soluble fraction of the aerial parts of Helicteres hirsuta Lour, collected in An Giang province, four compounds, including (+)-pinoresinol (1), (3,4-dihydroxyphenyl)acetic acid ethyl ester (2), 7-O-methylisoscutellarein (3) and ethyl 3-(3,4-dihydroxyphenyl)lactate (4) were isolated. Their chemical structures were elucidated based on the NMR spectroscopic analysis and comparison with data in the literature. All four isolated compounds (1‒4) showed good α-glucosidase inhibitory assay activity with the IC50¬ of 37.9, 69.1, 12.5, 9.4 µM, respectively, better than that of the positive control acarbose (IC50¬ 168.0)</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## A Fabrication and modification of a microcrystalline cellulose (MCC) prepared from cotton yarn 2022-11-18T09:05:54+00:00 Chi Pham Thi Le NGUYEN NGOC Ân <p>Cotton fibers were used to prepare the microcrystalline cellulose (MCC) by hydrolysis in acidic H2SO4 medium at different concentrations and heating. The prepared MCC sample was further grafted with maleic anhydride (MA) as an eco-friendly compatibilizer. Physicochemical properties of the fabricated materials were analyzed in comparison with those of the commercial Merck MCC one. The samples were subjected to infrared spectroscopy (FTIR) to confirm the purity of cellulose structure and the presence of MA grafted on MCC chains. The size distribution curve analysis showed that the MCC sample prepared under optimal conditions gave the same distribution as the commercial one, and the grafted sample gave a larger average size due to the aggregation. The X-ray spectroscopy (XRD) showed that the crystal structure was preserved through the modulation processes. Thermogravimetric analysis (TGA) was carried out to compare the heat resistance of the samples. Scanning electron microscopy (SEM) indicated that the prepared samples had similar morphology with Merck’s MCC.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Effect of the sputtering time on the characteristics of p-SnOx:Na films prepared by the reactive direct current magnetron sputtering method 2022-11-18T09:15:37+00:00 Pham Hoai Phuong Pham Ngoc Yên Nhi Bui Trung Hieu Nguyen Ngoc Phuong Tran Quang Trung Nguyen Manh Tuan <p>The fabrication of n- and p-type transparent oxide semiconductor films is critical in the production of transparent electrical and optoelectronic components on the p‒n junction, particularly the p-type, because the maximum of the valence band formed by the 2p orbitals of oxygen and their local (narrow) dispersions have formed deep levels, making difficult in doping of acceptor impurities in p-type oxide semiconductors. Among the p-type transparent oxide semiconductor films that have been studied so far, the p-type SnOx film which had outstanding electrical conductivity and optical transparency, is a good candidate for constructing a p‒n junction with another n-type semiconductor in homogeneous or heterogeneous form. In this paper, a Na-doped SnOx film was produced from Sn + 3 at% Na alloy target using the reactive sputtering process at a temperature of 200 0C. XRD, XPS, AFM, Hall, and UV-Visible techniques were used to evaluate the effect of sputtering duration on the structural and electro-optical properties of SnOx:Na films. The results of the survey showed that when the sputtering time increased from 7 minutes to 14 minutes, 21 minutes, and 35 minutes, the film thickness increased, resulting in an increase in the crystal size, a decrease in the grain boundary, and an increase in carrier mobility, all of which lead to a reduction in the film's resistivity. However, as the film thickness increased, the transmittance dropped and the optical bandgap shrinked.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Triterpenoids and triterpenoid saponins from leaves of Bougainvillea spectabilis 2022-11-18T13:11:37+00:00 Nga Thi Vo Lien Thi My Do Quy Bao Pham Tuyet Thi Anh Nguyen <p>The genus Bougainvillea with about 18 species belonging to the family Nyctaginaceae is a widespread group throughout the world. Bougainvillea spectabilis was traditionally used in Indian and Mexico for treatment hepatitis, cough, and diarrhea. Ethanolic and methanolic extracts from leaves and stems of this plant showed anti–inflammatory activity. Some pharmacological studies have focused on antidiabetic activity of this species. Some extracts from leaves, bark exhibited hypoglycemic, -glucosidase, and amylase inhibitor activities. Phytochemical investigations have reported the isolation of flavonoids, triterpenoid saponins, and steroids. Leaves of B. spectabilis were collected and extracted with ethanol at room temperature by maceration method to obtain the ethanolic extract. By partitioning with n–hexane, ethyl acetate successively yields n–hexane and ethyl acetate extracts. Column chromatographies on normal phase silica gel, reversed–phase RP–18, and Sephadex LH–20 were used to isolate compounds 1–6. Their chemical structures were elucidated by HRESIMS, 1D, and 2D–NMR and compared with those reported in the literature, including lupeol (1), (20S)–3β–acetoxylupan–29–oic acid (2), maslinic acid (3), 3–O––D–(6'–O–methyl)glucuronopyranosyloleanolic acid (4), 3–O––D–(6'–O–ethyl)glucuronopyranosyloleanolic acid (5), and 3–O––D–glucopyranosyl–(14)––D–(6'–O–methyl)glucuronopyranosyloleanolic acid (6). All these compounds were isolated for the first time from the genus Bougainvillea.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Adenine phosphoribosyl transferase (SmAPRT) is an appropriate reference gene for quantitative gene expression analysis by RT-qPCR in different tissues as well as in the response to some specific stress conditions of eggplant (Solanum melongena L.) 2022-11-18T20:41:54+00:00 Vy Le Uyen Khuat Vi Thi Tuong Bui Hong Thi Anh Pham Thuong Thi Hong Nguyen <p>Eggplant (Solanum melongena L.), an important vegetable crop because of its nutritional and medicinal values, is often attacked by insects and pathogens. Quantitative gene expression analysis by reverse transcription‒quantitative PCR (RT‒qPCR) is an effective and common approach to analyze the function of genes involving in the stress responses in eggplant. The RT‒qPCR method always included the step of normalizing the expression data of the target gene to that of a stably expressed internal reference gene to ensure the accuracy of the quantitative results. This paper presented the evaluation of the transcriptional expression of adenine phosphoribosyl transferase (SmAPRT) gene in different tissues of S. melongena (young leaf, mature leaf, stem, root, flower, and fruit) under normal conditions. Besides, the expression of SmAPRT was also measured in leaf tissues of plants damaged by mechanical wounding, plants treated with stress signal molecules induced by methyl jasmonate (MeJA) or methyl salicylate (MeSA), and untreated control plants. PCR with a SmAPRT-specific primer pair (SmAPRT-qF as forward primer and SmAPRT-qR as reverse primer) amplified a 103-bp fragment from S. melongena with the efficiency of 92.7%. This value was within the recommended range (90‒110%). The Ct values of qPCR reactions using cDNA template from the wounded plants or plants treated with MeJA or MeSA were not statistically significantly different from the Ct ones of the control plants. This SmAPRT gene was also stably expressed in all tested eggplant tissues. Therefore, SmAPRT would be used as a reference gene to normalize expression data of genes of interest in different tissues as well as in the response of S. melongena to the specific stress conditions as stated above.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Population dynamics of Perisesarma eumolpe in the storm fracture area of Can Gio mangrove forest 2022-11-18T20:59:52+00:00 Nguyen Thi Ngoc Ngan Tran Le Quang Ha Tran Ngoc Diem My <p><em>Perisesarma eumolpe</em>, the dominant species living in the damaged area caused by Durian storm in the Can Gio mangrove forest, had the role of changing the sedimentary structures for easier plant regeneration, contributing to the growth and development of the small soil organisms and playing role in the natural process of mangroves. This paper presented the ecological population structure, seasonal structural changes, growth and development of this species. The investigation based on the size distribution, density, biomass, sex ratio, and reproductive rate of the population and restoration of the forest ecosystem were evaluated. These recorded a <em>P. eumolpe</em> total population of 6169 individuals, including 3749 males (accounting for 60.77%) and 2420 females (accounting for 39.23%). The ratio of male to female individuals was 1: 0.65. August was the month when the most egg-bearing females was recorded. The first time-egg-bearing female had a carapace with the size of 9 mm. The moulting of crabs took place at every month of the year where the highest molting rate was from October to March, and the lowest was in April. The carapace size of individuals in the intact forest area was larger than those in the damaged one (D2F &gt; D1F &gt; D2Hcut &gt; D1Hcut &gt; D1Hnat). The crab density ranged from 268 individuals (in September) to 639 individuals (June) per month. The crab biomass ranged from 504.09 g per month to 1161.03 g per month. The highest biomass was recorded in June (1161.03 g/month), followed by in August (1139.56 g/month), and in May had a total biomass of 1074.4 g/month. The population growth and the development had the tendency of early maturation at smaller sizes and increased individual density in fractured habitats. This was the way that the species adapt to the conditions of a natural forest regeneration.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement## Chemical constituent investigation on the fraction 6 from the n-hexane extract of the stems of Placolobium vietnamense N. D. Khoi & Yakovlev 2022-11-18T21:12:16+00:00 Tuyet Thi Ngoc Huynh Lien Thi-My Do <p>Placolobium vietnamense N. D. Khoi &amp; Yakovlev, known as ‘Rang rang Viet’ in Vietnam, is an indigenous perennial plant distributed in Dak Nong and Kontum provinces, belonging to four species of the genus Placolobium (Fabaceae) found in Vietnam. Although the plant has been used as folk remedies for snakebites, debility, to increase strength after childbirth or to treat a number of other diseases, however, there still have been few studies on its chemical constituents. This paper presented the investigation on the chemical composition of the fraction 6 of the n-hexane of the stems of Rang rang Viet, collected at Dak Nong provinceresulted in the isolation of six compounds being determined as mackaiin (1), medicarpin (2), 3,9-dimethoxy-6a-hydroxypterocarpan (3), caviunin (4), daidzein (5) and aloe-emodin (6). Their chemical structures were elucidated by MS, 1D, and 2D–NMR as well as compared with data in the literatures. The isolated compounds were also investigated for their α-glucosidase inhibitory activity. The results showed that six compounds were more active than acarbose, with IC50 values of 11.0 – 32.8 μg/mL. All isolated compounds were reported for the first time in the genus Placolobium.</p> 2022-09-30T00:00:00+00:00 ##submission.copyrightStatement##