Examination of the Astrophysical-Rate Variations of the Key Reactions in the rp-Process due to Mass Uncertainties

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.

Potential of Visual Basic 6.0 in Teaching and Studying Physics

Duy Nguyen Ngoc 한국물리학회 2022 새물리 Vol.72 No.7

Computer programs play an important role in education and studies on subjects in natural science. Using computers, distance teaching and studying physics became easier, especially during the Covid-19 pandemic. Visual Basic 6.0 has emerged among various programming languages as a potential tool for physicists due to its simplicity and interactive graphical interface. This programming language does not require users' extensive computer knowledge or programming skills. With the hope of enhancing the efficiency of teaching and studying physics, I hereby present Visual Basic 6.0 potential to create graphical-user-interface (GUI) computer programs for creating a virtual laboratory, simulations, and numerical calculations. This study is used to enhance the effectiveness of computer programs in teaching, learning and doing research in physics.

An Approximation of the Synthesis Cross Section for the Unknown 126th Element via 58Ni + 251Cf and 64Zn + 248Cm Combinations

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.

MRTOF-S: a toolkit for pre-estimating precise mass measurements using MRTOF spectrometer

Duy Nguyen Ngoc,Uyen Nguyen Kim,채경육 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.80 No.9

An accurate estimation of the masses of exotic nuclei is important for obtaining a better understanding of the nuclear structure and for astrophysical calculations. Because most nuclear masses of unstable isotopes far from beta stability are highly uncertain, precise mass measurements are necessary. Among recent advanced techniques, the multiple-reflection time-of-flight (MRTOF) has emerged as a good device for measuring the precise masses of short-lived isotopes with high mass-resolving power. Before conducting mass measurements in laboratories, it is necessary to pre-estimate the beam production rate, separability of ions, mass resolving power, etc. Hence, a computer code named MRTOF simulator (MRTOF-S) was developed. In this study, we report the development procedure, usage, and application of the MRTOF-S toolkit.

Intra-Organizational Factors Affecting Business Performance: An Empirical Study in Vietnam

Khuong Ngoc MAI,Thao Thi Thanh NGUYEN,Phuong Ngoc Duy NGUYEN,Khoa Tien TRAN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.10

In the era of industry 4.0 with the robust digital transformation, especially under the trigger of the Covid-19 pandemic, the process of transforming businesses to achieve the desired business performance depends much on the mindset transformation of each member of the organization, beginning with the thoughts of leadership and stakeholders. This study will evaluate the relationship between leadership’s strategic reasoning perspectives on employee engagement or commitment and the company’s reputation, thereby directly or indirectly affecting organizational performance. The study examines data from 382 companies out of 500 samples in typical industries in Vietnam using the exploratory factor analysis (EFA) and partial least squares structural equation modeling (PLS-SEM) techniques. The results show that holistic thinking is closely related to employee retention and corporate reputation, thereby increasing the business outcomes of the organization, whereas there was no evidence to support analytical thinking in this study. As a consequence, transforming the business to achieve the desired business performance is heavily reliant on changing the mindset of each member of the organization, beginning with the top leaders and influencers of the business. This will assist Vietnamese leaders in gaining a comprehensive understanding of corporate governance and controlling the relationships between organizational constructs.

A Numerical Calculation of the Nuclear Spin-Parity and Magnetic Moment Based on the Single-Particle Shell Model

Nguyen Ngoc Duy,Latsamy Xayavong,Nguyen Kim Uyen,Vinh Nguyen Thanh Pham,Tran Viet Nhan Hao 한국물리학회 2019 새물리 Vol.69 No.10

Nuclear physics is an obligatory subject for the general physics program of undergraduates in most of the natural science universities worldwide. In nuclear physics, the shell model is one of the most important models, and is well used to determine the spin-parity and the magnetic moment of a nucleus. Over ten years of teaching general physics, we have realize that most undergraduate students find calculating these parameters by using this shell model to be difficult due to the classification of the subshells and the intrinsic spin of nucleons. With the hope to help these students, in the present study, we introduce a graphical-user-interface (GUI) program to execute our selfdeveloped Shell Model Calculator (SMC) code written in the Visual Basic 6.0 (VB6) programming language. Our SMC validation results for the quantum quantities in a series of nuclei Z = 1 - 20 were compared with experimental data and found to be in good agreement. In general, we successfully developed an SMC program that can be used for teaching, learning, and researching nuclear physics in universities.

Re-examination of Energy-Loss Straggling Calculations of Alpha Particles at 5.486 MeV

Nguyen Ngoc Duy,Nguyen Kim Uyen,Vinh N. T. Pham 한국물리학회 2020 New Physics: Sae Mulli Vol.70 No.2

We report on an evaluation of energy-loss straggling calculations performed using the LISE++ code and theoretical models. The energy-loss straggling of the alpha particles at 5.486 MeV in Al, Cu, Ag, Tb, Ta, and Au was calculated by using the LISE++ code and the Titeica model. The results of the calculations were compared to the measured data to improve the accuracy of the straggling predictions. The results show that the straggling is increased by the energy loss at a rate of 8.0 keV/%. The uncertainties of the LISE++ and Titeica calculations were reduced to about 15% by adding fitting parameters. We also propose a new semi-empirical formula which well reproduces the measured data with an uncertainty of about 20% for 5.486-MeV alpha particles in the materials used in the research.

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.

The Effect of Two-Dimensional Factor on Municipal Civil Servants’ Job Satisfaction and Public Policy Implications

Nguyen Ngoc Duy Phuong,Mai Ngoc Khuong,Le Huu Phuc,Le Nguyen Thanh Dong 한국유통과학회 2018 The Journal of Asian Finance, Economics and Busine Vol.5 No.3

The purpose of this study was to examine the effect of two-dimensional factor of motivators and hygiene on civil servants’ job satisfaction using the partial least square structural equation modeling (PLS-SEM) as a technique employed to analyze the measurement and structural models. Exploratory study was deployed to evaluate the relationship among variables. By using multistage stratified sampling, statistical data was collected from a survey of 441 public municipal civil servants who have employed in various levels (municipal government, districts and communes) in Vietnam. The findings provided evidence that hygiene factors (relationship with leader, salary, relationship with coworker and working environment) directly impact on civil servants’ job satisfaction. Meanwhile, only career development factor from motivators significantly influenced on public employee’s job satisfaction. Based on the empirical results, the hygiene factors of job satisfaction are more dominated that the motivators one. This finding suggests that municipal governments should focus policies on improving the hygiene factors which lead to higher job satisfaction on civil servants. Gaining a thorough understanding of the determinants of job satisfaction toward municipal public servants will enable policy makers to grasp the factors that results in retaining employees. Finally, the policy makers can use this knowledge to promote civil servants’ job satisfaction.

Key Determinants of Repurchase Intention toward Organic Cosmetics

Phuong Ngoc Duy NGUYEN,Vinh Tan NGUYEN,Nguyen Ngoc Thao VO 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.3

This paper aims to discover factors and their influences degree to repurchase organic cosmetic in Vietnam. In addition, this research also discloses the main segments that have high demand re-buying intention based on demographic groups of gender, age, income, educational level, job, type of products, and place of production. Twenty-eight scale was designed based on previous studies and adjusted to match the 5-point Likert scale to conduct measurement. By using survey method to test hypotheses and set up conceptual models to collect 295 Vietnamese consumers who have experience in consuming organic cosmetic by explain the results through Smart PLS software. The findings show that there is positive attitude of customers to the intention of acquiring organic cosmetics, green perceived and customer satisfaction. In addition, customer satisfaction, knowledge of products, safety values, and environmental protection consciousness also play important roles to form a positive attitude of customers for products. Moreover, the consciousness of green living of consumers accounts for a high proportion in creating customer satisfaction for organic products. The results show useful information for current premises to determine the factors that influence the decision to repurchase organic cosmetic product, that provide business strategies.