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INDONESIA
Science and Technology Indonesia
Published by Universitas Sriwijaya
ISSN : 25804405     EISSN : 25804391     DOI : -
Core Subject : Science, Social, Engineering,
Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Environmental Science Materials Science & Nanotechnology Physics
An international Peer-review journal in the field of science and technology published by The Indonesian Science and Technology Society. Science and Technology Indonesia is a member of Crossref with DOI prefix number: 10.26554/sti. Science and Technology Indonesia publishes quarterly (January, April, July, October). Science and Technology Indonesia is an international scholarly journal on the field of science and technology aimed to publish a high-quality scientific paper including original research papers, reviews, short communication, and technical notes. This journal welcomes the submission of articles that covers a typical subject of natural science and technology such as: > Chemistry > Biology > Physics > Marine Science > Pharmacy > Chemical Engineering > Environmental Science and Engineering > Computational Engineering > Biotechnology Journal Commencement: October 2016
Arjuna Subject : -
Articles 551 Documents
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The Use of Probability and Edge Analysis to Solve the Multi-Period Degree Constrained Minimum Spanning Tree Problem Wamiliana; Junaidi, Akmal; Gamal, Mohammad Danil Hendry; Thamrin, Taqwan
Science and Technology Indonesia Vol. 9 No. 4 (2024): October
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2024.9.4.999-1008

Abstract

The goal of the Multiperiod Degree Constrained Minimum Spanning Tree (MPDCMST) problem is to determine the smallest weight-spanning tree that satisfies the vertex installation criterion for each period and maintains the degree requirement in each vertex. This issue emerges as a network connection problem. The degree requirement indicates the reliability of each vertex, and the vertex connection/installation requirement denotes the priority vertices that must be inserted in the network within a specific time frame. The installation is split up into multiple phases/stages. This is because of various considerations such as severe weather, budgetary limitations, etc. In this research, two algorithms for solving the MPDCMST using probability hybridized with Prim’s modification, and edge analysis are proposed. The algorithms are implemented on the undirected complete graph of orders 10 to 100. The solutions are compared with some heuristics which are already in the literature. The results show that the proposed algorithms perform better.
Relation Between the First Zagreb and Greatest Common Divisor Degree Energies of Commuting Graph for Dihedral Groups Romdhini, Mamika Ujianita; Nawawi, Athirah
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.1-8

Abstract

The commuting graph for a finite group G, ΓG, has a set of vertices G \ Z(G), where Z(G) is the center of G, and vp,vq ∈ G \ Z(G) in which vp ≠ vq , are adjacent whenever vpvq = vqvp. The entries of the first Zagreb matrix (Z1) of ΓG are either the summation of the degrees of two adjacent vertices, or zero for non-adjacent vertices and also for the diagonal entries. Meanwhile, the entries of the greatest common divisor degree matrix (GCDD) of ΓG are the greatest common divisor of the degrees of two adjacent vertices and zero otherwise. The Z1-energy is determined by the sum of absolute eigenvalues of the corresponding Z1-matrix, whereas GCDD-energy is the sum of absolute eigenvalues of the GCDD-matrix. In this study, we find the spectral radius and the energies of ΓG for dihedral groups of order 2n, D2n, associated with Z1- and GCDD-matrices. It is found that Z1-energy is equal to twice GCDD-energy, whereas GCDD-energy is similar to maximum and minimum degree energies that were reported earlier in previous literature.
Modeling of Human Development Index Using Bayesian Spatial Autoregressive Approach Yanuar, Ferra; Wulandari, Sintya; Asdi, Yudiantri; Zetra, Aidinil; Haripamyu
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.72-79

Abstract

Spatial regression analysis is a technique employed to examine the relationship between independent and dependent variables in datasets that exhibit regional neighborhood influences or spatial effects. When a spatial effect exists for the independent variable, the Spatial Autoregressive (SAR) regression can be utilized. The Maximum Likelihood Estimation (MLE) is a commonly used parameter estimator for SAR. However, due to the limitations of MLE, the Bayesian method provides an alternative approach for parameter estimation. This study compares the results of SAR estimations using both MLE and Bayesian methods to determine the most accurate estimation model. Both methods were implemented in this research to model the factors affecting the Human Development Index (HDI) in East Java Province for the year 2022. The findings indicate that the Bayesian SAR offers a superior proposed model compared to the MLE SAR. The factors influencing the HDI in East Java Province in 2022 include poverty, per capita expenditure, and the presence of an upper middle-class manufacturing industry.
Complexation and Colour Stability of Anthocyanins from the Extracts of Java Plum Fruits (Syzygium cumini) with Selected Metal Cations (Al3+, Fe3+, and Ca2+) at Various pHs Wathon, Muhammad Hizbul; Susilowati, Endang; Ariani, Sri Retno Dwi; Sari, Latifah
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.43-55

Abstract

Anthocyanins are highly coloured polyphenols, a class of flavonoids, which are natural, non-toxic, and water-soluble compounds. Because of that, anthocyanins have been used in numerous applications, such as natural colorants for foods, beverages, and textiles. However, anthocyanins have some drawbacks regarding their stability towards temperature, pH, and light, leading to degradation. One method to improve anthocyanins’ stability can be achieved through a complexation reaction of anthocyanins with metal cations. Thus, this study aimed to investigate the stability and colour profiles of anthocyanins extracted from Java Plum fruits (Syzygium cumini) complexed with Al3+, Fe3+, and Ca2+ ions in pH 1-12. Previously, anthocyanins from Java Plum fruits have been identified by LC-MS as cyanidin-3-O-glucoside ([M]+, m/z 449.3), delphinidin-3-O-glucoside ([M]+, m/z 465.3), and petunidin O-glucoside ([M]+, m/z 479.3). The ATR FTIR was also performed to confirm the functional group of anthocyanins. The colour of each solution at different pH was evaluated by UV-Vis Spectrophotometer at 200-800 nm. Complexation of anthocyanins with Al3+, Fe3+, and Ca2+ ions showed various colours at different pHs. The complexation of anthocyanins with Al3+ at pH 4-5 developed a blue colour. The intensity of the blue colour increases with an increase in Al3+ ion concentration. This investigation showed the potential application of anthocyanin-metal chelation for the textile industry due to the range of colour produced. Furthermore, the complexation of anthocyanins to produce blue colour can be an alternative in food industries as this colour is difficult to obtain in acidic pH.
Anticancer Effectivity of Nanocrystals Derived from Mangosteen (Garcinia mangostana) Peel Extract on Leukemia HL-60 Cells Gondokesumo, Marisca Evalina; Novilla, Arina; Prahastuti, Sijani; Kusuma, Hanna Sari Widya; Widowati, Wahyu; Zahiroh, Fadhilah Haifa; Hadiprasetyo, Dhanar Septyawan; Surakusumah, Wahyu
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.228-237

Abstract

Leukemia, characterized by abnormal leukocyte proliferation, ranks ninth in Indonesia as the most common cancer. While treatments such as chemotherapy and radiation effectively target cancer cells, they also risk damaging healthy blood cells. This has spurred interest in exploring low-toxicity herbal compounds as potential therapies, with mangosteen peel emerging as a widely researched option. Nanotechnology, which has the potential to enhance the bioavailability of herbal compounds, is also a focus of extensive research. This study objective was to assess the impact of Mangosteen Peel Nanocrystal (MPN) on HL-60 leukemia cells by analyzing various parameters, including cytotoxicity, reactive oxygen species (ROS) levels, senescence, and gene expression changes. MPN was prepared with high-speed milling and characterized using particle size analyzers, microscopy, and stability assessments. HL-60 cells were cultured and subjected to MPN treatment. Cytotoxicity was evaluated using WST-8 assays, ROS levels were assessed using flow cytometry, and senescence analyses using Senescence-Associated b-Galactosidase Staining. AKT and FLT-1 gene expression were determined via qRT-PCR. MPN has been successfully characterized as a nanoparticle based on size, stability, and morphology. MPN has an impact on leukemia cells by increasing cytotoxicity, decreasing ROS levels, inducing senescence, and modulating AKT and FLT-1 gene expressions. The findings suggest potential implications for MPN in targeting leukemia cells. The study sheds light on the promising effects of MPN in leukemia cell models, indicating its potential applications in targeting cancer cells, inducing senescence, decreasing ROS levels, and modulating gene expressions related to cell survival and proliferation.
Improved Maximum Likelihood Estimator of the Extended Rama Distribution with Application to Lifetime Data Sungboonchoo, Chanakan
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.80-87

Abstract

Lifetime data are involved in numerous applied sciences, and the extended Rama (ER) distribution can be used to model such data. The maximum likelihood method is widely used for estimating the parameters of any distribution, particularly with large sample sizes. However, its effectiveness diminishes for small or moderate sample sizes due to the potential for biased estimates. This study improves the maximum likelihood estimator (MLE) of the extended Rama distribution by using two bias-corrected methods based on the Cox-Snell and parametric bootstrap approaches. Monte Carlo simulation was examined in terms of average bias and root mean square error (RMSE). The results indicate that the proposed bias-corrected estimators perform well in reducing both bias and root mean square error, thereby improving the accuracy of the estimates. Conversely, the maximum likelihood estimator exhibits relatively poor performance. Overall, the parametric bootstrap method outperformed the others, even when applied to small and moderate sample sizes. Additionally, the bias-corrected estimators were applied to a real dataset.
Optimizing Generalized Linear Models for Real Estate Investment Risk: A Hybrid Genetic Algorithm and IRLS Approach Abubakar, Hamza; Misiran, Masnita; Mansor, Kamarun Hizam; Sabri, Shamsul Rijal Muhammad
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.88-100

Abstract

Generalized Linear Models (GLMs) serve as a powerful extension of traditional linear regression, enhancing statistical analysis capabilities. This study employs a GLM to forecast the Return on Investment (ROI) within Nigeria’s real estate and construction sectors, utilizing a comprehensive dataset that includes data from the Nigerian Stock Exchange (NSE) and macroeconomic indicators from the National Bureau of Statistics (NBS) and the Central Bank of Nigeria (CBN), spanning 2017 to 2023. The model integrates critical macroeconomic indicators, including Gross Domestic Product (GDP) growth, the Consumer Price Index (CPI), Interest Rates (IR), and the Unemployment Rate (UR), while also considering interaction effects and non-linear terms to enhance predictive accuracy. Two methods were used to assess the GLM: Genetic Algorithms (GLM-GA) and Iteratively Reweighted Least Squares (GLM-IRLS), both of which revealed significant insights. Adjusted R2 values ranged from 0.68 to 0.73, with the highest in 2019 (0.73) and the lowest in 2021 (0.68). The Bayesian Information Criterion (BIC) exhibited variation, with values between 365.50 in 2019 and 386.30 in 2021, indicating differing model efficiency across years. Investment risk metrics, such as Value at Risk (VaR) and Conditional Value at Risk (CVaR), showed upward trends, with VaR increasing from 7.50 in 2017 to 9.20 in 2022, and CVaR rising from 7.00 to 8.70 in the same period, reflecting heightened risk exposure. The findings underscore the sensitivity of ROI predictions to macroeconomic conditions and highlight the challenges of forecasting amid economic volatility. This study emphasizes the substantial impact of macroeconomic factors on ROI and the necessity of considering these variables in investment risk assessments.
Effect of the Nano-Silica Addition on the Mechanical Properties of Polymer Concrete Septriansyah, Verinazul; Saloma; Nurjannah, Siti Aisyah; Saggaff, Anis; Usman, Arie Putra; Ngian, Shek Poi
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.9-17

Abstract

The latest advances in science and technology have positioned nanomaterials at the vanguard of contemporary research. Nano silica (SiO2) is an illustrative example of a nanomaterial extensively utilized in concrete manufacturing due to its properties as a pozzolan. The objective of this study is to elucidate the characteristics of nano silica and its effect on the performance of polymer concrete through experimental methods. X-ray diffraction (XRD) tests indicate that nano silica exhibits a high amorphous phase. Consequently, nano silica enhances the C-S-H gel formation reaction, producing more robust and denser specimens. The maximum compressive strength reached 45.23 MPa when adding 0.4% nano-silica with a specific gravity of 1573.33 kg/m3. For comparison, concrete without nano silica had a maximum compressive strength of 40.05 MPa with a particular gravity of 1610.67 kg/m3. Observation using a scanning electron microscope (SEM) showed that the nano-silica mixture exhibited excellent particle distribution as an activating agent that could enhance the strength of the specimens. Nevertheless, the observed reduction in compressive strength might be affected by several factors, including particle clusters and the presence of compounds carried by the fine aggregates that influence the mechanical properties of polymer concrete. Integrating nano-silica is pivotal in enhancing the compressive strength and reducing the specific gravity of polymer concrete specimens. The increased strength and decreased specific gravity render nano silica a promising additive for polymer concrete applications.
Synthesis and Characterization of Hydroxyapatite Composites Based on Tutut (Belamya Javanica) and Magnetite by Coprecipitation as Adsorbents of Pb Metals Ion Charlena; Nazriati; Marita Soebrata, Betty; Dicky Iswara, Muhammad
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.111-122

Abstract

Increased industrial activity can result in the emission of pollutants into the environment, such as heavy metals, which are a significant source of concern. A practical approach to reduce this problem is to utilize Pb metal adsorption. This study aims to synthesize HAp from Bellamya javanica clam shells and characterize the HAp-Fe3O4 composite as a Pb metal ion adsorbent. FTIR and XRD analysis results showed the successful fabrication of the composite, resulting in a crystal dimension of 7.63 nm and a crystallinity level of 84.80%. SEM characterization showed a porous structure with a particle size of 10.98 um. Adsorption studies of Pb(II) ions showed that the HAp-Fe3O4 composite efficiently adsorbed Pb(II) ions, with the adsorption efficiency increasing from 95.80% to 98.40%. The adsorption isothermal model of the HAp-Fe3O4 composite follows the Freundlich model with a 1/n value of 0.31 and a KF value of 25.35 L/g. The adsorption kinetics study of the HAp-Fe3O4 composite follows the pseudo second-order model with an R2 value of 1, and the thermodynamic study shows the Gibbs free energy is negative, which indicates that the adsorption process is thermodynamically optimal and spontaneous. In addition, the enthalpy value is positive, indicating that the interaction between the adsorbent and lead ions is endothermic, and the entropy is negative, indicating the reduction of random collisions of lead ions in the solid (adsorbent) and aqueous solution during adsorption.
Enhanced Performance of Epoxy Resin-Polyimide Hybrid Composites with Aminated Carbon Nanofibers Filler Saraswati, Teguh Endah; Saputri, Dini Deviana; Raharjo, Wijang Wisnu
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.152-164

Abstract

Incorporating epoxy resin (ER) and polyimide (PI) with supporting filler will exhibit composites with exceptional mechanical, thermal, and electromagnetic shielding properties. This research investigates the preparation of aminated carbon nanofiber (CNF) as a filler in epoxy resin-polyimide hybrid composites. The preparation of the CNF filler was initially done by the purification process through dissolution in toluene and vacuum annealing at 800°C for 3 hours. The amine modification of CNF was done by reacting CNF with ethylenediamine, sodium nitrite, and sulfuric acid. The aminated CNF was then mixed with polyimide precursor (oxydianiline and pyromellitic dianhydride), becoming poly(amic acid)-filler. The last step was combining poly(amic acid)-filler with epoxy resin diglycidyl ether bisphenol A and polyaminoamide as hardener. The Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) images of CNF showed the overlapped bundle fibers with the average fiber diameter around 100-120 nm. The successful amine modification was analyzed through Fourier-Transform Infrared (FTIR) analysis by the functional group emergence of C–N (∼1153 cm-1), N H (3737 cm-1), primary amine N–H (1534 cm-1), and better dispersion in water. The aminated filler shows a better distribution in the polymer matrices observed through macroscopic images and a higher hardness value. The FTIR of composites shows the increasing intensity in the N–H, C O amide, and C–H functional groups, indicating the highly covalent bonds between polymers and the aminated CNF filler. The TGA graph shows the recognizable termination of the polyimide and epoxy resin matrices as major components in the composite. The ER-PI composites with aminated CNF filler show improved mechanical properties in the hardness, tensile properties, and electromagnetic interference (EMI) shielding efficiency by around three-fold higher than composites with unmodified CNF filler.

Page 41 of 56 | Total Record : 551

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