Science and Technology Development Journal 2019-07-15T11:42:59+00:00 Phuc Van Pham Open Journal Systems The priming role of dendritic cells on the cancer cytotoxic effects of cytokine-induced killer cells 2019-07-15T11:42:59+00:00 Binh Thanh Vu Nguyet Thi-Anh Tran Tuyet Thi Nguyen Quyen Thanh-Ngoc Duong Phong Minh Le Hanh Thi Le Phuc Van Pham <p><strong>Introduction</strong>:<em> In vitro</em> cultivation of DCs and cytokine-induced killer cells (CIK cells) - a special phenotype of T lymphocyte populations — for cancer treatment has gained significant research interest. The goal of this study is to understand whether the priming from DCs helps CIK cells to exert their toxic function and kill the cancer cells.</p> <p><strong>Methods</strong>: In this research, DCs were differentiated from mononuclear cells in culture medium supplemented with Granulocyte-macrophage colony-stimulating factor (GM-CSF), and Interleukin-4 (IL-4), and were induced to mature with cancer cell antigens. Umbilical cord blood mononuclear cells were induced into CIK cells by Interferon-γ (IFN-γ), anti-CD3 antibody and IL-2. After 4-day exposure (with DC:CIK = 1:10), DCs and CIK cells interacted with each other.</p> <p><strong>Results</strong>: Indeed, DCs interacted with and secreted cytokines that stimulated CIK cells to proliferate up to 133.7%. In addition, DC-CIK co-culture also stimulated strong expression of IFN-γ. The analysis of flow cytometry data indicated that DC-CIK co-culture highly expressed Granzyme B (70.47% ± 1.53, 4 times higher than MNCs, twice higher than CIK cells) and CD3+CD56+ markers (13.27% ± 2.73, 13 times higher than MNCs, twice higher than CIK cells). Particularly, DC-CIK co-culture had the most specific lethal effects on cancer cells after 72 hours.</p> <p><strong>Conclusion</strong>: In conclusion, co-culture of DCs and CIK cells is capable of increasing the expression of CIK-specific characteristics and CIK toxicity on cancer cells.</p> <p>&nbsp;</p> <p>&nbsp;</p> 2019-05-27T22:39:52+00:00 ##submission.copyrightStatement## Critical concentration of the exotic nuclei in the 232Th chain for the alpha analysts 2019-07-15T11:42:58+00:00 Ngoc Duy Nguyen Thi To Vy Vo Kim Uyen Nguyen <p>The critical concentration plays an important role in the consideration of the analysts, such as gamma or alpha analyzers, for the isotopic analysis. Since the <sup>232</sup>Th isotope and its a-decay daughters are abundant in the environments of soils, rocks and water, it is necessary to investigate the content of these isotopes to reduce the risks of health. In this work, the critical concentrations of the mentioned radioactive nuclei were estimated based on their radioactivities for the alpha analysts. The a-decay half-lives of the nuclei in the decay chain of the <sup>232</sup>Th isotope were re-examined for the radioactivities. The semi-empirical formulae proposed by Viola-Seaberg, Royer and Poenaru were applied to the estimation. The predicted half-lives were normalized by their average values and compared to the data (NuDat) of the National Nuclear Data Center, Brookhaven National Laboratory. The results show that there exist a large uncertainty, 15% - 95% dispersed from the average values (in decimal logarithmic scale), of the half-lives evaluated by each models. Most of average half-lives are close to the NuDat data except the multi-decay-mode isotopes. The relationships between the estimated half-lives and the NuDat data are deduced as linear functions. The decay-constant deviations due to the half-life uncertainty are in the range of 1% - 120% from the average values. The large radioactivity uncertainty due to the half-lives estimated by the three models should be paid an attention for considering the environmental samples for the analysis of the natural exotic isotopes using alpha spectrometers. By assuming an efficiency of 100%, the critical concentration for the alpha analyst of the <sup>232</sup>Th nucleus is found to be in the range 1.5 – 2.5 microgram/(l or kg).</p> 2019-06-07T14:43:38+00:00 ##submission.copyrightStatement## A combined Euler deconvolution and tilt angle method for interpretation of magnetic data in the South region 2019-07-15T11:42:57+00:00 Hai Hong Nguyen Liet Van Dang Vuong Van Vo <p><strong>Introduction</strong>: The purpose of this paper is to determinate the position, depth, dip direction and dip angle the faults in the South region of Vietnam from the total magnetic intensity anomalies, that reduced to the magnetic pole (RTP).</p> <p><strong>Methods</strong>: Based on the Oasis Montaj software, we proposed a new way to compute the positions and the depth to the top of the faults by combining the Tilt angle and the Euler deconvolution methods. In addition, the angle and direction of the dip of theses faults were also determined by considering maximum of the total horizontal derivative of the RTP upward continuation at the different height levels.</p> <p><strong>Results</strong>: The results show that there are 12 faults along the longitudinal direction, latitudinal direction, Northwest — Southeast direction and Northeast — Southwest direction with the mazimum depth is about 3100 m and the dip angle changes in the range of 65-82◦.</p> <p><strong>Results</strong>: These indicate that these methods are valuable tools for specifying the characteristics of geology, contribute to give and confirm the useful information on geological structure in the South region of Vietnam.</p> <p>&nbsp;</p> 2019-06-07T23:21:10+00:00 ##submission.copyrightStatement## Synthesis of cellulose graft ionic liquid using silanization reaction 2019-07-15T11:42:56+00:00 Ut Dong THACH Thi Lan Nhi Do Ngoc Lan Anh Do Minh Huy Do <p><strong>Introduction</strong>: Ionic liquids (ILs) have attached many attentions due to their interesting physicochemical properties. However, ionic liquids have several disadvantages including high viscosity, difficult to purify, separate and recycle, and expensive. Therefore, supported ionic liquids (SIL) have been developed to overcome these problems. SIL based on cellulose material was conventionally synthesized by silanization reaction between ionic liquid trialkoxyl silane and hydroxyl groups on the surface of cellulose. However, low reactivity of cellulose hydroxyl groups causes the low efficiency of silanization reaction. With the aim to resolve these problems and improve the reactivity of cellulose silanization reaction, cellulose graft ionic liquid was synthesized and characterized.</p> <p><strong>Methods</strong>: Cellulose graft ionic liquid (CL-IL) material was synthesized by silanization reaction. The influence of reaction condition such as IL/CL (w/w) ratio, base catalyst (NH<sub>3</sub>) and agent coupling tetraethyl orthosilicate (TEOS) on silanization reaction was investigated. The modified CL-IL materials were characterized using FT-IR, TGA, SEM. The ion exchange properties were evaluated via batch adsorption studies to evidence the efficiency of silanization reaction of cellulose.</p> <p><strong>Results</strong>: The study indicated that adding TEOS with NH<sub>3</sub> catalyst could significantly increase the number of imidazolium groups grafted on cellulose about 75% compared to the conventional approach. CL-IL material is an efficient anion exchange materials displaying fast kinetic adsorption and high capacity adsorption of MO up to 1.4 mmol g<sup>-1</sup>.</p> <p><strong>Conclusion</strong>: High-efficiency of cellulose silanization was obtained by using coupling agent TEOS and base catalyst. Therefore, the silanization reaction can be used for synthesis divers of functional cellulose materials. This approach can be aimed for the design of cheaper and high-performance materials for catalysis, polymer composite and adsorption in water treatment and depollution of industrial wastewater.</p> <p>&nbsp;</p> 2019-06-13T00:00:00+00:00 ##submission.copyrightStatement## Construction of expression plasmid for Bacillus subtilis using Pspac promoter and BgaB as a reporter 2019-07-15T11:42:53+00:00 Hanh Thi-Thu Phan Nguyen Ngoc Yen Nhi Le Thuy Tien Chu Thi Bich Phuong Le Thi Phuong Ngan Phan Thi Phuong Trang Hoang Duc Nguyen <p><strong>Introduction</strong>: In basic research, it is essential to use an inducible promoter which can be controlled to express a small amount of protein for studying their roles in the cell. Pspac, a well-known weak promoter for Bacillus subtilis, uses isopropyl β-D-1-thiogalactopyranoside (IPTG) as an inducer. However, plasmids carrying this promoter such as pHCMC05 still have a disadvantage which harbors a repetitive DNA fragment of about 200 bp, resulting in structural instability in Escherichia coli, causing difficulty during cloning.</p> <p><strong>Methods</strong>: In this study, we constructed a plasmid that does not carry the repetitive sequences and investigated plasmid structural stability in E. coli, then measured the β-galactosidase reporter gene (bgaB) expression in B. subtilis.</p> <p><strong>Results</strong>: The constructed plasmid pHT2002 was stable over 56 generations while pHCMC05-bgaB was structurally instable and ultimately lost after 42 generations. BgaB activities and Western-blot indicated that BgaB-coding gene under control of IPTG-inducible promoter Pspac could be expressed at low levels.</p> <p><strong>Conclusion</strong>: The study demonstrated that the new expression plasmid without the repeated sequences retained its structural stability in E. coli facilitating the cloning step. The expression plasmid with Pspac promoter for B. subtilis could be used to express a modest amount of the heterologous protein in the presence of IPTG.</p> <p>&nbsp;</p> 2019-06-19T00:00:00+00:00 ##submission.copyrightStatement## A further investigation on the chemical constituents from Euphorbia tirucalli growing in Binh Thuan province 2019-07-15T11:42:52+00:00 Huy Thuc Duong <p><strong>Introduction</strong>: <em>Euphorbia tirucalli L.</em> is a medicinal plant popularly distributed in Asian countries. In Vietnam, only one study on the polar extract the plant Euphorbia tirucalli growing in Binh Thuan province, Vietnam was reported, revealing several phenolic components. As of 2019, no chemical reports on the non-polar extract from the Vietnamese plant were found. This research described the isolation and elucidation of compounds isolated from the non-polar extract of E.<em> tirucalli</em> growing in Binh Thuan province.</p> <p><strong>Method:</strong> The n-hexane extract of this plant was carried out by using normal phase silica gel column chromatography, thin-layer chromatography, and gel chromatography (Sephadex LH-20). Analysis of spectroscopic data and a comparison of the NMR data with that in the literature led to the structural elucidation of isolated compounds.</p> <p><strong>Results</strong>: Three terpenoid compounds, euphol (1), lupenone (2), and vomifoliol (3), along with ergosterol peroxide (4), ferulic acid (5), and vanillic acid (6) were isolated and elucidated.</p> <p><strong>Conclusions</strong>: Among them, compound 3 and 4 were reported in the first time from <em>E. tirucalli</em>.</p> <p>&nbsp;</p> 2019-06-19T00:00:00+00:00 ##submission.copyrightStatement## Influence of indium and hydrogen co-doping on optical and electrical properties of zinc oxide thin films deposited by DC magnetron sputtering 2019-07-15T11:42:51+00:00 Nguyen Huu Truong Tinh Van Nguyen Tuan Anh Thanh Pham Dung Van Hoang Hung Minh Vu Hoi Cong Nguyen Thang Bach Phan Vinh Cao Tran <p><strong>Introduction</strong>: ZnO-based thin films, known as potential transparent-conducting oxides (TCO), have still attracted much attention in applications for good-performance electrodes and inner layers in solar cells. Recently, the research tendency has focused on improving carrier mobility rather than carrier concentration to enhance performance and response speed of TCO thin films. In this work, Indium, and Hydrogen co-doped ZnO (HIZO) thin films were deposited by using DC magnetron sputtering technique in hydrogen-plasma atmosphere.</p> <p><strong>Methods</strong>: Indium-doped ZnO ceramics were used as sputtering targets, in which, Indium content varied from 0.07 to 1.0 at.%. The electrical, optical, structural and surface morphological properties of the as-deposited films were investigated by using Hall effect-based measurement, UV-Vis spectra, X-ray diffraction (XRD) and fieldemission scanning electron microscopy (FE-SEM), respectively.</p> <p><strong>Results</strong>: As a result, the HIZO films sputtered from the 0.1 at.% In-doped ZnO target and at H2/(H2+Ar) ratio of 3.5% exhibit high electron mobility (47 cm2/Vs), the lowest resistivity (4.9x10<sup>-4</sup> Ω.cm) and sheet resistance (4.7 Ω/sq.), simultaneously, high average transmittance (&gt;80%) in the visible – near IR spectrum regions.</p> <p><strong>Conclusion</strong>: Based on these results, the HIZO films are considered as potential TCO thin films that can be well-used as transparent electrodes in solar cells.</p> <p>&nbsp;</p> 2019-07-07T00:00:00+00:00 ##submission.copyrightStatement## Application of variance reduction techniques in EGSnrc based Monte-Carlo method 2019-07-15T11:42:49+00:00 Tuan Duc Hoang Tai Thanh Duong Oanh Thi Luong Loan Thi Hong Truong <p><strong>Introduction</strong>: Monte Carlo (MC) is considered to be the most accurate method to calculate dose distribution in radiation therapy. However, the limitation of MC simulations is the long calculation time to reach the desired statistical uncertainty in the dose calculation as well as in clinical practice. To overcome the above limitations, Variance reduction techniques (VRTs) has developed and shorten the calculation time while maintaining accuracy. Therefore, the purpose of this study is the application of VRTs in code EGSnrc to find the optimal method for accelerator simulation and calculated dose distribution using MC method.</p> <p><strong>Methods:</strong> The linear Accelerator HPD Siemens Primus at the General Hospital of Dong Nai had been simulated by using BEAMnrc code and several variance reduction techniques such as: range rejection, photon forcing, bremsstrahlung photon splitting (uniform, selective and direction)... These VRTs were used under the same set of input parameters as histories of 2x10<sup>8</sup>, photon energy of 6 MV, structure, size and material of the phantom… The computational efficiency ε is calculated by the following equation ε = 1/T.σ<sup>2&nbsp;</sup>where T is the CUP time of calculation and &nbsp;σ<sup>2&nbsp;</sup>is an estimate of the variance, for evaluating and selecting the VRT which gives the best computational efficiency.</p> <p><strong>Results</strong>: The results showed a good agreement between the calculated dose and measured ones when applying different VRTs. These techniques were significantly reduced uncertainty in simulation compared the analog cases. Specifically, the efficiency of DBS and UBS improved by more than 90 times and 15 times compared with the analog instances, respectively. Rang rejection and photon forcing techniques also have<br>improved the efficiency of simulation, but not significantly.</p> <p><strong>Conclusions:</strong> The application of the VRTs for EGSnrc increase the efficiency of the simulation. VRTs is a powerful tool that should be applied for the simulation by code EGSnrc to improve calculation efficiency by reducing simulation time and its variance. Our results show that the direction bremsstrahlung splitting (DBS) gives the<br>best computational efficiency.</p> <p>&nbsp;</p> 2019-07-12T00:00:00+00:00 ##submission.copyrightStatement## A brief introduction to Quillen conjecture 2019-07-15T11:42:54+00:00 Tuan Anh Bui Thi Anh Nguyen <p><strong>Introduction</strong>: In 1971, Quillen stated a conjecture that on cohomology of arithmetic groups, a certain module structure over the Chern classes of the containing general linear group is free. Over time, many efforts has been dedicated into this conjecture. Some verified its correctness, some disproved it. So, the original Quillens conjecture is not correct. However, this conjecture still has great impacts on the field cohomology of group, especially on cohomology of arithmetic groups. This paper is meant to give a brief survey on Quillen conjecture and finally present a recent result that this conjecture has been verified by the authors.</p> <p><strong>Method</strong>: In this work, we investigate the key reasons that makes Quillen conjecture fails. We review two of the reasons: 1) the injectivity of the restriction map; 2) the non-free of the image of the Quillen homomorphism. Those two reasons play important roles in the study of the correctness of Quillen conjecture.</p> <p><strong>Results</strong>: In section 4, we present the cohomology of ring ​ which is isomorphic to the free module ​ over ​. This confirms the Quillen conjecture.</p> <p><strong>Conclusion</strong>: The scope of the conjecture is not correct in Quillens original statement. It has been disproved in many examples and also been proved in many cases. Then determining the conjectures correct range of validity still in need. The result in section 4 is one of the confirmation of the validity of the conjecture.</p> <p>&nbsp;</p> 2019-06-14T11:05:00+00:00 ##submission.copyrightStatement##