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Evaluation of $alpha$-decay Half-life for Measuring Concentration of Radioactive Nuclei
Nguyen Ngoc Duy,Phuong-Thao Ho 한국물리학회 2020 New Physics: Sae Mulli Vol.70 No.5
In this study, we employed the semi-empirical formulae proposed by Viola-Seaborg, Royer, and Poenaru to estimate the -decay half-lives of the radioactive isotopes in the 235;238U chains because they are important for alpha analysis and radioprotection. We found a large uncertainty of about two orders of magnitude, in the experimental data for the half-lives, as evaluated by using each model. The results showed that the current formulae are insufficient for isotopes that undergo a multi-decay mode or -decay probability less than 1:5%. The relations between the estimated halflives and the experimental data in NuDat Database were deduced as linear functions to improve the validity of the semi-empirical models. The large radioactivity uncertainty due to the half-lives calculated by using the three models should be a concerned for the analysis of the radioactive isotopes using alpha spectrometers. On the other hand, an approach for estimating sample sizes based on the -decay half-life in concentration analyses using alpha analysts is proposed for measurements of largely uncertain or unknown half-life isotopes.
Duy Nguyen Ngoc,Ho Phuong-Thao,Pham Vinh N. T.,Hoan Nguyen Thi Thu 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.1
In this paper, we estimate the production cross section of the unknown super-heavy nuclei 309, 312126 via 58Ni + 251Cf and 64Zn + 248Cm combinations by using approximation methods. For each reaction, the competition between compound nucleus (CN) formation and quasi-fission process is also analyzed. We found that the synthesis cross section for the 309126 isotope is about 3 fb, which is about 5 orders of magnitude higher than that for the 312126 nucleus. The results also suggest that a valley exists around the isotope with A = 313 in the production yields for the 126th element. Moreover, the synthesis of the 310-317126 isotopes is still a challenge for experimental techniques due to the small cross sections, which are less than 1 fb.
Duy Nguyen Ngoc,Ho Phuong-Thao,Uyen Nguyen Kim 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.10
We report on the variations of the astrophysical rates due to mass uncertainties of the exotic nuclei in rp-process reactions. With the current mass precision obtained in the AME2016 database, only the 71Br(p,γ)72Kr and the 65As(p,γ)66Se reactions have rate uncertainties of about 10% - 20% at T9 = 0.5 while the 61Ga(p,γ)62Ge, 61, 64, 65Ge(p,γ)62, 65, 66As, 68, 69Se(p,γ)^{69, 70}Br, 69,70Br(p,γ)70,71Kr, and 75Rb(p,γ)76Sr reactions have large uncertainties of more than 50%. If an uncertainty of 10% at T9 = 1.0 is to be achieved, the mass precisions for the isotopes must be less than 10 keV. Evaluations of the photodisintegrations corresponding to proton captures and β+ decays of the waiting points, 64Ge and 68Se, indicate that the orientation of the nucleosynthesis at these waiting points is still unknown due to the large astrophysical rate variations because of the mass uncertainties of the 65As and the 69Br isotopes. The astrophysical rate variations corresponding to the mass precision levels at specific temperatures are presented in this work.
( Ramachandran priyadharshini ),( Ngoc Phuong Thao Nguyen ),( Joon Ho Choi ),( Yun Chan Kang ),( Marimuthu Jeya ),( Jung Kul Lee ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.3
A high β-glucosidase (BGL)-producing strain, Stereum hirsutum, was identified and isolated and showed a maximum BGL activity (10.4 U/ml) when cultured with Avicel and tryptone as the carbon and nitrogen sources, respectively. In comparison with other BGLs, BGL obtained from S. hirsutum showed a higher level of activity to cellobiose (Vmax = 172 U/mg, and kcat = 281/s). Under the optimum conditions (600 rpm, 30oC, and pH 6.0), the maximum BGL activity of 10.4 U/ml with the overall productivity of 74.5 U/l/h was observed. BGL production was scaled up from a laboratory scale (7-L fermenter) to a pilot scale (70-L fermenter). When S. hirsutum was cultured in fed-batch culture with rice straw as the carbon source in a 70-L fermenter, a comparable productivity of 78.6 U/l/h was obtained. Furthermore, S. hirsutum showed high levels of activity of other lignocellulases (cellobiohydrolase, endoglucanase, xylanase, and laccase) that are involved in the saccharification of biomasses. Application of S. hirsutum lignocellulases in the hydrolysis of Pinus densiflora and Catalpa ovata showed saccharification yields of 49.7% and 43.0%, respectively, which were higher than the yield obtained using commercial enzymes.
Chien Minh Tran,Ngoc Thi‑Thanh Nguyen,Minh Hieu Ho,Vinh Khanh Doan,Khanh Loan Ly,Nhi Ngoc‑Thao Dang,Nam Minh‑Phuong Tran,Hoai Thi‑Thu Nguyen,Long Phuoc Truong,Thai Minh Do,Quyen Ngoc Tran,Hien Quoc Ng 한국섬유공학회 2023 Fibers and polymers Vol.24 No.1
In this study, we proposed a straightforward electrospun polycaprolactone (PCL) loaded with silver nanoparticles (SNPs)membrane fabrication process, in which SNPs were directly synthesized from silver nitrate (AgNO3) in PCL–acetone mixtureby gamma irradiation. The insolubility of AgNO3in PCL solution was solved using an auxiliary dimethyl sulfoxide solvent. As a physical approach, gamma rays readily converted silver ions into SNPs without the addition of harmful reductionagents, which reduced the cytotoxicity of the synthesized material. By avoiding some processes such as purification, solventremoval, or redispersion of SNPs, this method was more time-saving compared to other related studies. SNPs formation wasconfirmed by both UV–Visible spectrum (UV–Vis) and X-ray diffraction analysis. Scanning electron microscopy (SEM)revealed that the addition of SNPs significantly reduced the fiber diameter of PCL–Ag membranes compared to that of rawPCL. Uniform spherical-shaped SNPs incorporated in PCL fibers were observed under transmission electron microscopy(TEM). The tensile test showed that the electrospun PCL–Ag membranes exhibited good mechanical characteristics. Moistureeasily penetrated the porous microstructure of PCL–Ag, facilitating wound humidity regulation. Inductively coupledplasma-mass spectroscopy (ICP-MS) was employed to study the release profiles of SNPs at different time intervals. Overall,the PCL–Ag 500 ppm sample exerted excellent antibacterial activity against Pseudomonas aeruginosa and Staphylococcusaureus strains and low in vitro cytotoxicity.
Anti-inflammatory tirucallane saponins from Paramignya scandens.
Phan, Nguyen Huu Toan,Thuan, Nguyen Thi Dieu,Ngoc, Ninh Thi,Thao, Nguyen Phuong,Kim, Sohyun,Koh, Young Sang,Thanh, Nguyen Van,Cuong, Nguyen Xuan,Nam, Nguyen Hoai,Kiem, Phan Van,Kim, Young Ho,Minh, Cha Pharmaceutical Society of Japan 2015 Chemical & pharmaceutical bulletin Vol.63 No.7
<P>Five new tirucallane saponins, paramignyosides A-E (1-5), were isolated from the water fraction of the Paramignya scandens stem and leaves. Their structures were elucidated on the basis of spectroscopic evidence including high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) and one dimensional (1D)- and 2D-NMR. The effects of isolated compounds on pro-inflammatory cytokines were evaluated by measuring the production of interleukin (IL)-12 p40, IL-6, and tumor necrosis factor-α (TNF-α) in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs). Paramignyoside C (3) exhibited selective and potent inhibitory effect (IC50=5.030.19??M) on the production of IL-12 p40 comparable to that of the positive control, SB203580 (IC50=5.000.16??M). Further studies are required to confirm efficacy in vivo and the mechanism of anti-inflammatory effects.</P>
Dinh Tram Anh PHAN,Thi Thuy Ngan NGUYEN,Thi Khanh Nhi NGUYEN,Tran Thien An NGUYEN,Van Si Dan PHAN,Ngoc Phuong Thao HO,Kim Xuan DO,Trong Luan NGUYEN 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.5
The outbreak of the COVID-19 pandemic has had a significant impact on the Vietnamese economy. In the midst of a complex disease that compelled people to limit their interaction, customers’ shopping habits shifted from “offline” to “online” transactions. Mobile payments have also grown in popularity. The goal of this study is to figure out what factors influence the use of mobile payments by hotel clients in Can Tho after COVID-19. The research team also examines how those factors influence customers’ willingness to use mobile payment and makes recommendations to better the current situation. Primary data was collected from 227 persons using online surveys and processed with SPSS software for this study. To analyze the correlation relationship between the elements determining the intention to use, the Cronbach alpha, EFA, Correlation, and Regression methods used to assess the scale are applied. Perceived Trustworthiness, Perceived Usefulness, and Perceived Ease of Use all have positive effects on customers’ propensity to use, according to the findings. Perceived Security, on the other hand, has no bearing. The findings of this study have significant theoretical and practical implications for the development of mobile payment services in Can Tho, particularly following the implementation of COVID-19.