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  • Vietnam National University Journal of Science  (102)
  • 1
    Online Resource
    Online Resource
    Synthesis and Properties of Some Polythiophenes Containing Benzo[d]thiazole Heterocycle
    Vietnam National University Journal of Science ; 2022
    In:  VNU Journal of Science: Natural Sciences and Technology ( 2022-12-03)
    Details
    In: VNU Journal of Science: Natural Sciences and Technology, Vietnam National University Journal of Science, ( 2022-12-03)
    Abstract: In this paper, some new polythiophenes containing benzo[d]thiazole heterocycle were synthesized by the oxidative polymerization in chloroform using iron(III) chloride as a catalytic oxidant. Infrared (IR) spectroscopy and ultraviolet–visible (UV-Vis) spectroscopy analyses confirmed that the polymerization reaction successfully took place and the absorption band at 497 nm is typical for π–π* transition in the conjugated polythiophenes. The polymers are composed of relatively uniform particles using field emission scanning electron microscopy (FESEM) method. Based on thermal gravimetric analysis (TGA), the polymers had average thermal stability in the atmosphere when decomposed completely at 500 oC. The polymers exhibited fluorescence emission at about 516 nm due to the conjugated chain in the polymers.
    Type of Medium: Online Resource
    ISSN: 2588-1140 , 2615-9317
    URL: Article
    DOI: 10.25073/2588-1140/vnunst.5376
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2022
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  • 2
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    Fabricating Ultra-thin Silicon Nitride Membranes Suspended on Silicon Wafer
    Vietnam National University Journal of Science ; 2021
    In:  VNU Journal of Science: Mathematics - Physics Vol. 37, No. 1 ( 2021-03-12)
    Details
    In: VNU Journal of Science: Mathematics - Physics, Vietnam National University Journal of Science, Vol. 37, No. 1 ( 2021-03-12)
    Abstract: Ultrathin silicon nitride SiNx membrane suspended on a silicon wafer is a popular two-dimensional platform in MEMS applications. The unsupported membrane has a low thermal conductivity, is electrically insulated, and very robust against mechanical impact. Remarkably thin, it is difficult to fabricate and manipulate. Recently equipped with a dual chamber system for plasma enhanced chemical vapor deposition (PECVD) and reactive ion etching, we calibrate it to deposit silicon nitride Si3N4, silicon dioxide SiO2, and to dry etch these materials. Based on the superb quality of Si3N4, we perform a through-wafer etch that creates suspended Si3N4 membranes. The recipe is reliable and reproducible. We analyze the membrane’s chemical composition and optical properties. Although created by PECVD, the membrane is so robust that it survives multiple lithography steps. It extends our capability to study thermal transport at the submicron scale as well as to fabricate micron size devices for MEMS applicati
    Type of Medium: Online Resource
    ISSN: 2588-1124 , 2615-9341
    URL: Article
    DOI: 10.25073/2588-1124/vnumap.4518
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2021
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  • 3
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    Online Resource
    Protein Drug Production
    Vietnam National University Journal of Science ; 2023
    In:  VNU Journal of Science: Medical and Pharmaceutical Sciences Vol. 39, No. 2 ( 2023-06-20)
    Details
    In: VNU Journal of Science: Medical and Pharmaceutical Sciences, Vietnam National University Journal of Science, Vol. 39, No. 2 ( 2023-06-20)
    Abstract: The group of protein drugs has been developing very strongly, promising great advances in diagnosis, treatment, prevention, and human health improvement. Protein drug production is a large area of research, requiring advanced scientific and technological expertise, and integration of multi-disciplinary technology from fields such as biology, genetics, biotechnology, protein extraction and purification, and pharmaceutical manufacturing. As protein drug manufacture involves biosynthesis processes using different cell lines, biopharmaceuticals have some distinct characteristics from small-molecule synthetic drugs, such as variability of biological processes, diversity of synthetic proteins, therefore leading to some differences in research and development, approval procedures, bioactivity testing, quality control and quality assurance and the production of “generic” biopharmaceuticals - biosimilars. This article provides an overview of protein drug production from the initial stage to the finished product process, to identify and promote training activities, research and development, and knowledge transfer, contributing to the development of the biopharmaceutical industry in Vietnam, as well as effectively applying the drugs in clinical practice. Protein drug production is a valuable industrial field, with the goal of not only protecting and taking care of people's health but also developing national research, manufacturing, scientific and technological capacity, and bringing economic value. Keywords: Protein drug, biopharmaceuticals, formulation, biosimilars.     
    Type of Medium: Online Resource
    ISSN: 2588-1132 , 2615-9309
    URL: Article
    DOI: 10.25073/2588-1132/vnumps.4526
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2023
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  • 4
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    Influence of Calcium on the Structure and Hydrophilic of CaTiO3 Coating on Titanium Implants
    Vietnam National University Journal of Science ; 2023
    In:  VNU Journal of Science: Mathematics - Physics Vol. 39, No. 3 ( 2023-09-24)
    Details
    In: VNU Journal of Science: Mathematics - Physics, Vietnam National University Journal of Science, Vol. 39, No. 3 ( 2023-09-24)
    Abstract: Calcium titanate (CaTiO3), a multi-metal oxide has received extensive attention in recent years, due to its unique structural features, high chemical stability, strong catalytic activity, inexpensiveness, low toxicity, and easy synthesis. In this work, we have focused our research on and investigated the influence of Ca weight on the microstructure and properties of CaTiO3 films. CaTiO3 films on TiO2 nanotube templates were synthesized using hydrothermal method at 200 oC for 24 h. The TiO2 template was synthesized by anodizing using a Ti plate. The synthesized materials were analyzed on their crystal phase, surface morphology, Raman characterization, surface roughness, and hydrophilic properties by X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), 3D optical Profilometer, and contact angle measurement. The synthesized film exhibited a morphological transformation from nanotube morphology to nanopillars. Notably, the hydrophilic properties and the surface roughness of the CaTiO3 films were altered after hydrothermal treatment of the TiO2 nanotube template. These findings could potentially lead to the development of highly efficient materials for use in biomedical implants.  
    Type of Medium: Online Resource
    ISSN: 2588-1124 , 2615-9341
    URL: Article
    DOI: 10.25073/2588-1124/vnumap.4841
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2023
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  • 5
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    Online Resource
    Study on the Influence of Processing Oil on the Physical Mechanical Properties and Adhesion of Ethylene Propylene Diene Monomer (EPDM) Rubbers to Polyester Fabrics
    Vietnam National University Journal of Science ; 2020
    In:  VNU Journal of Science: Natural Sciences and Technology Vol. 36, No. 2 ( 2020-06-26)
    Details
    In: VNU Journal of Science: Natural Sciences and Technology, Vietnam National University Journal of Science, Vol. 36, No. 2 ( 2020-06-26)
    Abstract: In this paper, the influence of paraffinic oil on the physical mechanical and thermal properties of three EPDM rubbers types Buna EP T.6465, Keltan 5260Q and Keltan 6160 D have been investigated. The results showed that the tensile strength and the elongation at break of Keltan 5260Q and Keltan 6160 D with 10 phr paraffinic oil represent the improvement of 57.8% to 57.6% and 71% to 81% respectively, compared to EPDM rubbers without paraffinic oil. The mean peel force of EPDM keltan 6260D with 10 phr paraffinic oil loaded is about 36% and 32.5% higher than that of keltan 5260Q and EP.T 6465 respectively. Beside that at the suitable paraffinic oil contents, the thermal resistance of Keltan 5260 Q and 6160D seems to be a little higher than that of without processing oil and these EPDM rubbers are suitable for application to high thermal resistance rubber products.
    Type of Medium: Online Resource
    ISSN: 2588-1140 , 2615-9317
    URL: Article
    DOI: 10.25073/2588-1140/vnunst.4986
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2020
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  • 6
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    Góp phần nghiên cứu tổng hợp một số N-(ω-azidoalkyl)isatin thế từ các isatin thế và không thế
    Vietnam National University Journal of Science ; 2022
    In:  VNU Journal of Science: Natural Sciences and Technology Vol. 38, No. 1 ( 2022-03-15)
    Details
    In: VNU Journal of Science: Natural Sciences and Technology, Vietnam National University Journal of Science, Vol. 38, No. 1 ( 2022-03-15)
    Abstract: Tóm tắt: Các dẫn xuất azide của isatin là các chất đầu cần thiết cho phản ứng click để tạo ra dị vòng 1,2,3-triazole. Các dẫn xuất N-(ω-bromoalkyl)isatin cần cho chuyển hoá được tổng hợp từ phản ứng thế nucleophile của các isatin tương ứng với các dibromoalkane thích hợp. Một số N-(ω-azidoalkyl)isatin có chứa nhóm thế hoặc không thế ở vòng benzene đã được tổng hợp bằng phản ứng của các N-(ω-bromoalkyl)isatin tương ứng đã tổng hợp được với natri azide. Phản ứng được thực hiện trong DMF khan với sự có mặt của KI với vai trò chất xúc tiến. Hiệu suất sản phẩm đạt được 30−85%. Abstract: Azide derivatives of isatins were the needed initial materials for click chemistry in order to form 1,2,3-triazoles. N-(ω-Bromoalkyl)isatins were prepared by nucleophilic reaction of (un)substituted isatins with appropriate dibromoalkanes. Some ω-azidoalkylisatins were synthesized by reaction of corresponding ω-bromoalkylisatins with sodium azide. The reactions were performed in dry DMF as solvent in the presence of KI as promotive agent. Product yields achived 30−85%.
    Type of Medium: Online Resource
    ISSN: 2588-1140 , 2615-9317
    URL: Article
    DOI: 10.25073/2588-1140/vnunst.5174
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2022
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  • 7
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    Phase Transition in the 2D XY Model with 3-Fold Nematic Interactions
    Vietnam National University Journal of Science ; 2022
    In:  VNU Journal of Science: Mathematics - Physics Vol. 38, No. 2 ( 2022-06-24)
    Details
    In: VNU Journal of Science: Mathematics - Physics, Vietnam National University Journal of Science, Vol. 38, No. 2 ( 2022-06-24)
    Abstract: In this work the results of the study on a generalization of the XY model with an additional q-fold nematic-like term through Monte Carlo simulations in two dimensions (2D) have been presented. While the conventional 2D XY model has only integer vortexes, the generalized 2D XY model has both integer and non-integer 1/q vortexes, making the phase diagram of the generalized 2D XY model is much richer than that of the conventional 2D XY model. Here, we located the phase transition between the disordered phase (P), the quasi-long-range order phase (F), and the nematic phase (N) for the case of q = 3. We provided the numerical evidence to clarify the N−F phase transition of either the first-ordered or second-ordered phase transition. The results showed that the N−F phase transition is the second-ordered, not the first-order phase transition.
    Type of Medium: Online Resource
    ISSN: 2588-1124 , 2615-9341
    URL: Article
    DOI: 10.25073/2588-1124/vnumap.4694
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2022
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  • 8
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    Removal of Phenol from Water by Commercial Coconut Shell Charcoal
    Vietnam National University Journal of Science ; 2023
    In:  VNU Journal of Science: Natural Sciences and Technology ( 2023-05-15)
    Details
    In: VNU Journal of Science: Natural Sciences and Technology, Vietnam National University Journal of Science, ( 2023-05-15)
    Abstract: In this study, phenol was adsorbed by commercial coconut shell charcoal (CSC), which is inexpensive, commercially available, non-toxic, and environmentally friendly. The measurements, namely the density functional theory (DFT) calculation, the energy-dispersive X-ray spectroscopy (EDS), and the Fourier-transform infrared spectroscopy (FTIR), were conducted to characterize the features of the CSC. The highest phenol removal efficiency reached 78.62% at optimal conditions (pH: 7, initial concentration of phenol: 20 mg/L, adsorption time: 120 minutes, and dosage of CSC: 2.5 g/L). The phenol adsorption process follows the Langmuir adsorption model with the coefficient R2 = 0.9964. The maximum adsorption capacity by the CSC was determined to be 14.32 mg/g. The process of desorption of phenol from CSC was most effective in the NaOH solution. On the other hand, the adsorption efficiency of CSC gradually decreased after five consecutive cycles. At the fifth use, the phenol uptake efficiency reached 22.2%.
    Type of Medium: Online Resource
    ISSN: 2588-1140 , 2615-9317
    URL: Article
    DOI: 10.25073/2588-1140/vnunst.5515
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2023
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  • 9
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    Spectroscopic Characteristics of Dual - Color CdSe/CdS/CdSe1-xSx/CdS Quantum Dot - Quantum Wells
    Vietnam National University Journal of Science ; 2022
    In:  VNU Journal of Science: Mathematics - Physics Vol. 38, No. 4 ( 2022-12-16)
    Details
    In: VNU Journal of Science: Mathematics - Physics, Vietnam National University Journal of Science, Vol. 38, No. 4 ( 2022-12-16)
    Abstract: In this work, preparation and spectroscopic characteristics of CdSe/CdS/CdSe1-xSx/CdS core/shell 1/well/shell 2 structure were presented. The obtained quantum dot - quantum well (QDQW) samples exhibited two emission peaks at 1.97 and 2.2 eV. Excitation power dependent photoluminescence (PL) of the QDQWs indicated that the integrated emission intensities of these peaks increase linearly with excitation power densities up to 1.3×102 mW/cm2. The temperature dependence of the bandgap energies of the QDQW’s core and well layer was well described using the Varshni expression. Evidence of the existence of “local wells” in the QDQW’s well layer that leads to a more significant change in the maximum position and full width at half maximum of the well’s emission peak compared to the core’s counterpart was discovered. Annealing samples resulted in the considerable increase of the well layer’s emission efficiency. Keywords: Quantum dot - quantum wells, dual - color, spectroscopic characteristics.
    Type of Medium: Online Resource
    ISSN: 2588-1124 , 2615-9341
    URL: Article
    DOI: 10.25073/2588-1124/vnumap.4769
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2022
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  • 10
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    Protein Drugs
    Vietnam National University Journal of Science ; 2022
    In:  VNU Journal of Science: Medical and Pharmaceutical Sciences Vol. 38, No. 3 ( 2022-09-23)
    Details
    In: VNU Journal of Science: Medical and Pharmaceutical Sciences, Vietnam National University Journal of Science, Vol. 38, No. 3 ( 2022-09-23)
    Abstract: Abstract: To serve health care, up to now, sciences have successfully developed many drugs with different effects. In general, in terms of chemical structure and effect characteristics, medicine can be classified into groups including inorganic drugs, small-molecule organic drugs, protein drugs (macromolecules), and recently a new group of drugs has been formed, separate from the protein drug class, which is the RNA drugs. In terms of pharmacological effects, in general, the mechanisms of protein drugs and small-molecule organic drugs do not differ too much because they all act at a particular stage related to pathological manifestations. Protein drugs in the process of development have gone through many different stages, with different origins, from extraction and isolation from living tissues at an early stage to biosynthesis by recombinant technology and other modern biotechnology methods. To date, most of the proteins used in medicine have been produced through recombinant pathways, possibly through different semisynthetic steps to give the molecules more superior drug properties. Therefore, the group of protein drugs has an additional new name, biopharmaceuticals, to indicate their synthetic origin by biological methods. The research, development, and application of protein drugs into clinical practice are of great significance, helping to enhance the ability of medicine to control and treat many difficult-to-treat diseases today, bringing many opportunities to have good health for people. Keywords: Protein drugs, RNA drugs, Biopharmaceuticals, Inorganic drugs, Small-molecule organic drugs, Drug development, Cytokine, Enzyme, Hormone peptide, Stem cell, Recombinant technology, Biosimilar. *    
    Type of Medium: Online Resource
    ISSN: 2588-1132 , 2615-9309
    URL: Article
    DOI: 10.25073/2588-1132/vnumps.4436
    Language: Unknown
    Publisher: Vietnam National University Journal of Science
    Publication Date: 2022
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