Vietnam Academy of Science and Technology: Journals Online
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Tungsten Oxide Nanoplates: Facile Synthesis, Controllable Oxygen Deficiency and Photocatalytic Activity
No full textMonoclinic tungsten oxide (WO3) nanoplates were synthesized via a two-step simple process: acid precipitation at room temperature to prepare WO3.H2O nanoplates and annealing at high temperature (400 and 500 oC) in ambient air to obtain WO3 nanoplates. The effect of annealing temperature on physical properties (morphology, oxygen deficiency, crystallinity, optical properties, and photocatalytic activity) of WO3 nanoplates was studied. At both two studied annealing temperatures, all samples have the stable monoclinic structure and visible light-range optical bandgap, but the morphology and photocatalytic activity of the samples vary significantly with annealing temperature. At higher annealing temperature (500 oC), the sample has both nanoplate and nanograin morphologies with round edges, higher crystallinity, larger optical bandgap (2.71 eV), and lower photocatalytic activity. The sample annealed at 400 oC has nanoplate morphology with sharp edges, lower optical bandgap (2.63 eV), and higher photocatalytic which shows a high potential for photocatalytic application under visible light irradiation. The effect of the annealing temperature on the properties of WO3 nanoplates is assigned to the dehydration, the coalescence, and/or the melting processes at high temperatures. Dehydration causes the formation of oxygen vacancy – oxygen deficiency. The coalescence and/or the melting result in the changing of morphology and the decrease of the oxygen vacancies. These results imply a simple, cost-effective method to prepare highly oxygen-deficient WO3 nanoplates
Synthesis and Characterization of Monodisperse Hydrous Colloidal Zirconia Nanoparticles
No full textThe suspension of hydrous colloidal zirconia particles (CZPs) was prepared from zirconium oxychloride solutions via thermal hydrolysis at acidic condition and at boiling point of 110 ºC for 72 h. Characterization of the obtained suspension and dried solid ZrO2 was performed by DLS, FESEM, FTIR, XRD and TGA measurements. Purification via dialysis membrane can maintain the monodispersion of the colloidal suspension when stabilized at pH6. The suspension contained almost sheet-like colloidal particles with amorphous structure with size ranges from 70 to 140 nm in wide and about 40-60 nm in thickness. The formula of hydrous CZPs can be expressed as ZrO2.2H2O
Effects of Additives and Conductors on Properties of Conducting Porous Composite Based on Activated Carbon
No full textClimate change is increasingly clear and threatening to human life. One of the consequences of climate change is the increase of sea level leading to saline intrusion and serious shortage of fresh water. Today, some technologies are used to treat saline water such as Reverse Osmosis technology (RO), Multi-Effect Distillation (MED) technology, and Multi-Stage Discharge Technology (MSF), Electrodialysis (ED) and Capacitive Deionization (CDI). Among them, CDI technology is a technique for energy-saving and economical. The conductive composite electrode based on activated carbon from Tra Bac coconut shell charcoal were fabricated which were used as a electrode for CDI device. In this study, effect of adhesives and conductors on characterization and properties of the materials was investigated. The adhessive of PVDf and conductor of CNTs was chosen. With ratio of AC/CNTs = 9:1, the composite had a specific surface area of BET of about 517 m2/g and pore size of 1.71 nm
Optimization of culture conditions for squalene production and squalene extraction method of Thraustochytrium sp. TN22
No full textSqualene, a natural triterpene with important roles as antioxidant, skin hydrating, cardio-protection and detoxifier, has attracted the attention of researchers in the world. This study investigated the optimal culture conditions for squalene production and to develop a method for squalene extraction and purification from cell suspension of Thraustochytrium sp. TN22. The results showed that squalene production by the strain Thraustochytrium sp. TN22 was optimum at 2% glucose, 0.5% yeast extract and 0,14% mixture of vitamins (B1, B6 and B12) at 28 oC for 2 days of cultivation. At the optimum conditions, the dry biomass, squalene content and productivity were approximately 9.3 g/L, 9.9 mg/g DCW and 95.3 mg/L, respectively. Time-dependence on cell lysis and extraction solvents were selected as the extraction parameters. The obtained results showed that the highest squalene production of 178.1 mg/100 g biomass was obtained in cell lysate at alkaline medium (pH = 10), at 60 oC for 6 hours and n-hexan was the best solvent for squalene extraction. Squalene was then purified on silica gel column using n-hexan as the mobile phase and 90% purity of squalene was archived. Our obtained results are promising for the commercial productions of various value-added compounds from species belong to the genus Thrautochytrium in Vietnam.
Study on the expression of interleukins in patients with twin-twin transfusion syndrome
No full textTwin-twin transfusion syndrome (TTTS) is an unusual and serious condition that occurs in twin pregnancies when identical twins share a placenta but develop discordant amniotic fluid volumes. The TTTS has a high risk of fetal death and birth defects if left untreated. IL-1β, IL-6 and IL-8 have been shown to play an important role in preterm birth in twin pregnancies, which is one of the consequences of TTTS. This study quantified plasma levels of IL-1β, IL-6 and IL-8 in twin pregnant women with (n = 52) and without TTTS (n = 73) by ELISA and analyzed the association of interleukin expression levels with TTTS. The results showed that plasma concentrations of IL-1β and IL-8 were low and not significantly different between the first trimester and the second trimester of pregnancy, between the patients with and without TTTS or between patients with TTTS before and after treatment. IL-6 levels showed no significant difference between first trimester and second trimester of pregnancy or between patients with and without TTTS. Importantly, IL-6 levels were significantly elevated in TTTS patients after surgical treatment compared to those before surgical treatment. In conclusion, IL-6 may be considered as a potential marker for the prognosis of surgical treatment of TTTS
Comparison of morphogenesis and anatomy between hairy roots and adventitious roots of Ngoc Linh ginseng (Panax vietnamensis Ha et Grushv.)
No full textIn this study, morphogenesis and anatomy of adventitious roots and hairy roots of Ngoc Linh ginseng (Panax vietnamensis Ha et Grushv.) were compared. Adventitious roots were derived from four different samples (leaf, petiole, root and callus) in vitro cultured on medium SH supplemented with 5 mg/L IBA. Hairy roots were derived from callus infected with Agrobacterium rhizogenes strain ATCC 15834. The results showed that there were significant differences in morphogenesis and anatomy, the pathway of secondary roots formation, culture medium between adventitous roots and hairy roots. The hairy roots strongly grew and branched on the free-plant growth regulator medium. The secondary root of the hairy root was formed in two pathways: (1) The secondary root formation began at the vesicles system of main root; (2) The secondary root formation was independent of the vesicles system of main root; it kept developing in length and connected to the vesicles system of main root. On the other hand, growing adventitous roots only grew on the environment with exogenous auxin supplementation; also their branching ability were low. The secondary root formation of the adventitous root was started at the vesicles of the main roots and there was only one secondary root that was formed at an location of adventitous root. The results that obtained in this study will be the reference to identify two types of root
New records of cascade frogs of the genus Odorrana (Amphibia: Anura: Ranidae) from Vietnam
No full textOdorrana fengkaiensis was recorded for the first time from Vietnam based on a new amphibian collection from Cao Bang, Bac Kan, Bac Giang, Quang Ninh provinces. Sequences of the specimens from Vietnam were identical to those of the paratypes of O. fengkaiensis from China. In addition, O. trankieni was newly recorded from Hoa Binh and Bac Giang provinces, Northern Vietnam, including the first description of female individuals. Genetic divergence between O. trankieni from Vietnam and its sister species, O. nasuta from China, ranged from 1.42 to 2.66%. The intra-specific genetic distance within O. trankieni ranged from 0.68 to 1.88% between the northeastern and northwestern populations.
Plant tissue and cell culture in Vietnam: forty-five years of development and the future
No full textBy 2020, plant tissue and cell culture in Vietnam had undergone 45 years of research and development. For nearly half a century, plant tissue and cell culture has been developed to its full potential, especially with the development of genetics, biochemistry and molecular biology. It has contributed significantly to basic and practical researches in our country. In addition to contributions to domestic science and technology, plant tissue and cell culture in Vietnam has also made impressive imprints in the development of plant tissue and cell culture in the world. In this review, I will summarize the process of formation, development and important achievements as well as the challenges and future prospects of this potential field in Vietnam to provide information for researchers, managers, graduate students and other interested readers.
The regulatory role of peripheral blood mononuclear cell function by A20
No full textPeripheral blood mononuclear cells (PBMC) consist of lymphocytes (T cells, B cells, natural killer cells), monocytes and dendritic cells and play important roles in initiating and regulating immunity against pathogens or immunotolerance to allergens. Activation of PBMCs is induced upon exposure to multiple stimuli by the binding with toll-like receptors (TLRs), recognition elements of the innate immune system. A20 is a negative regulator of nuclear factor (NF)-κB-dependent immune reaction in response to TLR ligands. A20-deficient mice display severe inflammation, tissue damage in multiple organs, cachexia and premature mortality. Single nucleotide polymorphisms (SNPs) at A20 gene region in humans reduce the binding capacity of A20 to NF‐κB subunits, resulting in reduced expression and function of A20 and leading to the pathogenesis of autoimmune and cancers. Although the inhibitory role of A20 on immune cells including B, T and DC functions has been previously reported, the effect of A20 on PBMC function is not mentioned yet. The present study, therefore, explored whether A20 expression is involved in immunophenotypic changes, the release of cytokine production, cell migration, and apoptosis. To this end, immonophenotypic profile and cell apoptosis were examined by flow cytometry, secretion of inflammatory cytokines by ELISA and cell migration by a transwell migration assay. As a result, percentages of CD3+CD25+, CD19+CD25+, and CD11b+CD40+ expressing cells, the release of TNF-α and IL-1β and cell migration were enhanced in A20-silenced PBMCs. However, cell apoptosis was independent of the presence of A20 in PBMCs. In conclusion, these results attained in this study suggested that A20 expression might modulate the immune response in autoimmune disease and cancers
Conjugation of nanomaterials containing rare-earth ion Tb3+ with CD133 monoclonal antibody and its potentials for labeling colon cancer cells (HT-29)
No full textNanotechnology is the key technology that brings many important applications in biomedical research.Nanolantanites present high stability, easy fabrication and functionalization. Tb3+ ion-containing nanomaterial, a specific type of nanolantanites, possess great prospects. In addition, cancer stem cells (CSCs) are directlyrelated to drug resistance, metastasis, recurrent cancer, etc. Therefore, CSCs are considered as the target forcancer researching and for discovery of more effective therapies. CD133, a trans-membrane glycoprotein, isone of the typical markers that are found to appear very commonly on the surface of many types of CSCs. Inthis study, CD133 monoclonal antibody (MAb) was cojugated with nanomaterials containing Tb3+. Thecoupling between fluorescented nanomaterials containing Tb3+ ions and CD133 MAb was then incubated withhuman colon cancer cells (HT-29) to evaluate its ability to label CSCs in vitro. The results showed thatnanorods containing rare-earth based Tb3+ ions which were fabricated by hydrothermal method, present thelength of about 300 - 800 nm and the diameter in range of 40 - 50 nm. The Tb3+ nanoparticals also havehexagonal structure of terbium phosphate monohydrate and green illuminant. Tb3+ nanorods were also furthersurface silica coated and amino-silane functionalized. This nanostructure was successfully combined withmonoclonal antibodies against CD133 which labelled the surface marker of HT-29 human colon cancer cells.As a result, the combination of CD133+TbPO4@Silica-NH2 (functionalized surface) showed strongerluminescence than the CD133+TbPO4 unfunctionalized combination