https://publisher.uthm.edu.my/ojs/index.php/JST/issue/feed Journal of Science and Technology 2020-07-15T17:27:45+08:00 Ahmad Hadi Ali jst@uthm.edu.my Open Journal Systems <p>Journal of Science and Technology (JST) aim to publish original and high quality articles (be it in theoretical or applied perspectives) on all aspects of science and technology. This peer reviews journal seek to publish TWO (2) issues annually.</p> <p>JST is devoted in providing a platform for the publication of full-length articles focusing (and not limited) to research areas as listed below:</p> <p>Physcis, Chemistry, Mathematics, Statistic, Biodiversity, Food Science and Technology as well as Engineering and Education Science.</p> https://publisher.uthm.edu.my/ojs/index.php/JST/article/view/5201 Derivation of Repair and Mis-Repair DNA Double-Strand Breaks (DSBs) Model: A Case with Two Simultaneously DSBs Repair Condition 2020-06-21T09:19:23+08:00 Muhamad Hanis Nasir p4000@pps.umt.edu.my Fuaada Mohd Siam fuaada@utm.my <p>“A double-edged sword-like of ionizing radiation”, a common phrase used to describe the effect of irradiation to human cells. Our aim in this article is to study the dynamics of double-strand breaks (DSBs) damage on deoxyribonucleic acids (DNA) following irradiation. In particular, we derived a structured cell population model of DNA with respect to DSBs count and mis-repair DSBs, specifically in the present of two simultaneously DSBs repair. We also derived the characteristic of exact solution, which follows a Homologous-Cauchy condition of initial value problem. These results may give insights on modelling strategies of DNA response to irradiation.</p> 2020-06-21T09:05:52+08:00 Copyright (c) 2020 Journal of Science and Technology https://publisher.uthm.edu.my/ojs/index.php/JST/article/view/5259 The Film Thickness Effect on The Physical Properties of NiO Thin Films Elaborated by Sol-gel Method 2020-07-02T08:09:39+08:00 Said Benramache s.benramache@univ-biskra.dz <p>In this work, nickel oxide (NiO) was elaborated on glass substrate at by sol-gel technique. The NiO thin films were prepared with 0.8 M Ni(NO<sub>3</sub>)<sub>2 </sub>6H<sub>2</sub>O annealed at 600 °C for 2 h. The coating process was repeated for 13, 14, 15, 16 and 17 times to obtain a thin film, which corresponded to 124, 137, 143, 147 and 166 nm of film thickness. NiO thin films were observed as nanocrystalline with cubic structure at 166 nm with (111) and (200) peaks were observed. All NiO thin films have an average transmittance of about 80 % in the visible region. The NiO thin films have a variety in the band gap energy from 3.87 to 3.94 eV. Because of the effect of deposition times, the minimum value was found at 166 nm where this condition has the highest Urbach energy. The NiO thin films have an electrical conductivity which was increased from 7.94 x10<sup>-3</sup> to 84x10<sup>-3</sup> (Ω.cm)<sup>-1</sup> when film thickness increases from 124 to 137 nm. In the end, the electrical measurements were investigated by the four-point method, with the results show good electrical conductivity at 166 nm.</p> 2020-06-21T09:07:46+08:00 Copyright (c) 2020 Journal of Science and Technology https://publisher.uthm.edu.my/ojs/index.php/JST/article/view/5377 Numerical Performance of AlGaN/GaN High Electron Mobility Transistors under Hydrostatic Pressure and Temperature 2020-07-02T08:18:32+08:00 Rajab Yahyazadeh r.yahyazadeh@iaurmia.ac.ir Zahra Hashempour r.yahyazadeh@iaurmia.ac.ir <p>In this paper, drain-source current, in AlGaN/GaN high electron mobility transistors have been investigated. In order to obtain parameters of exact AlGaN/GaN high electron mobility transistors such as electron density, the wave function, band gap, polarization charge, effective mass and dielectric constant, the hydrostatic pressure and temperature effects are taken into account. It has been found that the drain-source current decreases with increasing temperature and increases with increasing hydrostatic pressure. The increase in temperature is equivalent to a negative virtual gate and an increase in the hydrostatic pressure equivalent to the positive virtual gate voltage. Moreover, the temperature and hydrostatic pressure effective mass dependence in high electron mobility transistor structures are investigated, and it is observed that the increase of hydrostatic pressure decreases the effective mass and the wave function penetrated to quantum barrier AlGaN. The calculated results are in good agreement with existing experimental data.</p> 2020-06-21T09:08:58+08:00 Copyright (c) 2020 Journal of Science and Technology https://publisher.uthm.edu.my/ojs/index.php/JST/article/view/6106 An Improved Confidence Interval for The Difference between Standard Deviations of Normal Distributions Using a Ranked Set Sampling 2020-07-02T08:27:59+08:00 Wararit Panichkitkosolkul wararit@mathstat.sci.tu.ac.th <p>In this paper, a confidence interval is derived for the difference between the standard deviations of normal distributions using the method of variance of estimates recovery. This confidence interval was improved using the estimators of the standard deviations using ranked set sampling (RSS) instead of the standard method using simple random sampling (SRS). An evaluation of the performance of the proposed confidence interval based on RSS compared to the existing one based on SRS was conducted via a Monte Carlo simulation study. The results revealed that the proposed confidence interval based on RSS performed more efficient than the existing one based on SRS in terms of the coverage probability and average length. A confidence interval comparison is also illustrated using a real data example in the area of medical science.</p> 2020-06-21T09:09:57+08:00 Copyright (c) 2020 Journal of Science and Technology https://publisher.uthm.edu.my/ojs/index.php/JST/article/view/5321 DFT Investigation on the Electronic Properties and Intramolecular Hydrogen Bond of Trans-Cis and Cis-Trans Methyl Substituted N-Benzoyl-N’-(2-pyridyl)thiourea 2020-07-06T11:25:55+08:00 Rafie Draman rafiedraman@gmail.com Mohd Sukeri Mohd Yusof mohdsukeri@umt.edu.my Maisara Abdul Kadir maisara@umt.edu.my <p>Five single molecule methyl substituted Benzoyl pyridinylthiourea compounds namely N-benzoyl-N’-(2-pyridyl)thiourea, N-benzoyl-N’-(6-methyl-2-pyridyl)thiourea, N-benzoyl-N’-(5-methyl-2-pyridyl)thiourea, N-benzoyl-N’-(4-methyl-2-pyridyl) thiourea and N-benzoyl-N’-(3-methyl-2-pyridyl)thiourea are investigate theoretically for <em>trans-cis</em> and <em>cis-trans</em> conformation at B3LYP 6-31G(d,p) level of theory. Electronic properties have been analyzed by Gaussian 09W package and AIMAll code. Methyl substituent and its position give noticeable effect to reactivity, stabilization, and hydrogen bond interaction strength. AIM prove that 6-methyl substituted on pyridyl ring has significant effect to preferent conformation.</p> 2020-07-05T14:31:37+08:00 Copyright (c) 2020 Journal of Science and Technology https://publisher.uthm.edu.my/ojs/index.php/JST/article/view/5710 On New Mathematical Modeling Measuring the Band Gap of Semiconductor in Nanomaterial 2020-07-15T17:27:45+08:00 Aisha Salem asalemresearch@gmail.com <p>The magnitude and character components (M&amp;C) band gap energy of semiconductor composite&nbsp;nanomaterial&nbsp;(SCN) is framed in this effort. The theoretical preparations&nbsp;supported&nbsp;by the energy increased by spacing the atoms in a crystalline state (solid energy) of the nano crystals compared to the bulk crystals. CdTe, CdSe, ZnSe, ZnTe&nbsp;and ZnS semiconductor&nbsp;composites were deliberated for the investigation of M&amp;C components band gap dynamism. In addition, an entropy definition was employed in terms of this energy. It is confirmed that the band gap (BG) energy of SCN is subjected to the atom magnitude and character. From the layout, it can be concluded that the band gap energy increases whenever the atomic magnitude&nbsp;of the semiconductor&nbsp;nanomaterial&nbsp;reducing. The results attained were associated with the obtainable experimental information, which sustain the ability of the layout described.</p> 2020-07-05T14:29:58+08:00 Copyright (c) 2020 Journal of Science and Technology