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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 616 Documents
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Comparative Valuation of Employee Stock Options Using CRR and Enhanced American Models with Vesting and Exit Effects Dara Puspita Anggraeni; Abdurakhman; Noorma Yulia Megawati
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.1033-1045

Abstract

Employee stock options (ESOs) are required to be measured at grant-date fair value under existing accounting standards, yet classical lattice models typically assume frictionless exercise behavior. In practice, ESO contracts incorporate vesting restrictions, employee exit risk, and behavioral exercise triggers that can materially affect valuation outcomes. This study provides a structural comparison between the Cox-Ross-Rubinstein (CRR) American model and the Enhanced American (EA) framework within a unified binomial setting in which the probabilistic return process constant to isolate employment-related frictions. An analytical dominance result is established, showing that EA valuations remain strictly below the CRR American benchmark under these frictions. Numerical experiments confirm the theoretical ordering and quantify its economic magnitude: under moderate frictions, valuation gaps remain limited to approximately 2-3%, whereas under high exit intensity and conservative trigger thresholds, the discount expands substantially to approximately 65-69%, particularly for long-dated and near-the-money contracts. Heatmap analysis across volatility and dividend regimes further demonstrates that this dominance ordering persists under economically relevant parameter variations. The findings indicate that employment-related frictions constitute a materially significant component of ESO valuation and that model choice within fair-value measurement frameworks can meaningfully influence reported compensation expenses.
The Utilization of Beta, Sigmoid, and Linear Fuzzy Membership Functions Discretization to Classify AISI 1045 Surface Roughness Levels Using the Ensemble of Multiple Naïve Bayes Yulia Resti; Irsyadi Yani; Ismail Thamrin; Dewi Puspitasari; M. A. Ade Saputra; Endang S. Kresnawati; Des A. Zayanti; Novi R. Dewi
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.855-866

Abstract

Currently, researchers in various fields are using fuzzy discretization for decision-making. Discretization construction for numerical data involving a combination of fuzzy membership functions is significant because it can affect the performance of the model used. Classification of AISI 1045 surface roughness with satisfactory performance is needed to improve efficiency and extend the service life of AISI 1045 products. This study utilizes three fuzzy membership functions: beta, sigmoid, and linear in constructing fuzzy discretization on machining factors and tangential roughness levels to classify the axial roughness level of AISI 1045. Classification is performed using an ensemble of single naïve Bayes methods integrated with fuzzy discretization. These single methods are distinguished based on the combination of fuzzy membership functions used in the discretization. The results of the study show that the integration of fuzzy discretization through a combination of fuzzy membership functions, namely beta, sigmoid, linear, and fellow beta functions in the MNB method provides different performance, even the performance of MNB with fuzzy discretization using a combination of beta and sigmoid is almost the same or not statistically significantly different from the performance of the ensemble method. However, the ensemble method built provides the best performance for classifying the surface roughness level of AISI 1045, with Accuracy, Precision, Recall, F1-score, AUC, Balanced Accuracy, and G-Mean of 85.42%, 55.33%, 73.14%, 62.63%, 71.71%, 81.71%, and 81.04%, respectively.
Clustering in Chemical Characteristics and Contaminant Metal Levels of Indonesian Sago Starch: A Comprehensive Analysis of Purity and Quality Agus Budiyanto; Muhammad Romli; Elisa Anggraeni; Edi I. Wiloso; Mulyana Hadipernata
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.758-772

Abstract

Indonesia has the most sago plantations in the world, which means that sago can be used for a wide range of things, including food, animal feed, fuel, fiber, and fertilizer. However, Indonesian sago starch can’t be used more widely in either domestic or international markets because there isn’t enough information about its chemical composition and contaminant levels. This study examines the chemical composition and heavy metal levels of sago starch from various regions of Indonesia. The results show that the chemical properties of sago starch vary from province to province. For example, the carbohydrate content ranges from 84.26% to 94.93%, while the fat and protein content are relatively low. There are also reports of differences in the amounts of amylose and amylopectin. The levels of heavy metals are very low and meet international safety standards, which means that Indonesian sago starch is safe to eat. Sago starch from Indragiri Hilir, Banjarmasin, and Lingga exhibits chemical properties similar to those from Meranti, Indonesia’s primary sago-producing region, suggesting their potential as alternative sources. The appropriate amounts of amylose and amylopectin in these areas make it suitable for food products that require very high flexibility. These results support improving the use of sago starch and help raise the quality and safety standards for Indonesian sago products.
Bioactivity Study of Russelia equisetiformis Ethanol Extract as an MCF-7 Breast Cancer Cells Inhibitor with In vitro and In silico Approaches Rizq Rachmad Ramiizah; Dini Attala Hefa Insyira; Najwa Salsabila Hakim; Muhammad Rafly Aditya Firmansyah; Tukiran Tukiran
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.927-939

Abstract

Russelia equisetiformis has been used in traditional medicine, but its molecular mechanisms against breast cancer remain unexplored. This study aimed to investigate the cytotoxic potential of R. equisetiformis ethanol extract and elucidate its molecular interactions through a combined in vitro and in silico approach. Cytotoxicity evaluation using the Resazurin assay demonstrated the extract’s activity against MCF-7 breast cancer cells with an IC50 value of 352.60 ± 0.23 ????g/mL. To understand the underlying mechanism, the identified bioactive compounds that passed the druglikeness test were analyzed using molecular docking against the Progesterone Receptor (PDB ID: 2W8Y) and Estrogen Receptor-alpha (PDB ID: 3ERT). Docking analysis revealed that these compounds form binding interactions with target receptors, providing insight into their potential mechanism of action, albeit with lower affinity compared to standard drugs (tamoxifen and anastrozole). Importantly, ADMET prediction using ProTox 3.0 highlighted apigenin, kaempferol, isokaempferide, and kaempferol 3-O-rhamnoside as the most promising primary candidates, demonstrating inactivity against hepatotoxicity, carcinogenicity, and cytotoxicity. These findings provide initial scientific evidence for the potential anticancer properties of R. equisetiformis compounds, indicating that all four compounds are safe and viable bioactive candidates for further development as non-toxic therapeutic agents.
Zagreb-Based Indices of Line Graph of Prime Coprime Graph for Integers Modulo Group Abdurahim; Mamika Ujianita Romdhini; Jihadil Qudsi
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.844-854

Abstract

In this paper, we investigate the line graph of the prime coprime graph associated with the integers modulo group. Explicit general formulas are derived for the first Zagreb index, the second Zagreb index, and the hyper-Zagreb index of the considered structures. A comparative analysis is performed between the newly obtained results and previously reported findings, highlighting structural differences and index growth behaviour under the line-graph transformation. Furthermore, a statistical analysis is conducted to explore the quantitative relationship between the prime coprime graph and its corresponding line graph with respect to the computed Zagreb-based indices. The results provide deeper insight into the structural complexity of algebraically defined graphs and clarify how degree-based topological descriptors evolve under graph transformations.
Shearing Stress-Induced Lipid Accumulation in Chlorella Cultivated in CO₂-Enriched Medium Modified with NaOH Ragil Pandu Sadewo; Devi Bentia Effendi; Nur Faiizah Aqiilah Firman; Putu Yudha Ugrasena; I Gusti Ayu Nadia Prasta Unique; Gema Puspa Sari; Khairul Anam
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.867-876

Abstract

Chlorella can produce MUFA and PUFA, such as linolenic acid, with an ideal ω-3: ω-6 ratio content (1:1). This study investigates the effects of centrifugation-induced shear stress on lipid metabolism and fatty acid composition in Chlorella sorokiniana and Chlorella vulgaris cultivated in CO2-enriched TAP medium modified with NaOH as an inorganic carbon source. Shear stress was applied during the exponential growth phase to assess its influence on biomass productivity, biochemical composition, and lipid accumulation under nutrient-rich (P1) and nutrient-deficient (P2) conditions. Results revealed that C. sorokiniana showed superior adaptability to shear stress compared to C. vulgaris, showing a 64.7% increase in lipid content and maintaining higher unsaturated fatty acid (UFA) proportions, particularly polyunsaturated fatty acids (PUFAs). In contrast, nutrient deprivation in P2 promoted saturated fatty acid (SFA) accumulation as an energy storage adaptation. Biomass recovery in P1 indicated the need for nutrient availability in sustaining growth following mechanical treatments. The fatty acid profile of C. sorokiniana was dominated by UFA (67.2%), including ω-3 and ω-6 PUFAs, whereas C. vulgaris showed a higher SFA (42.2%). These findings suggest that moderate shear stress can stimulate lipid biosynthesis and improve the nutritional quality of microalgal lipids without compromising cell viability, provided sufficient nutrients are available. The combination of shear stress induction and optimized nutrient management offers a promising strategy to enhance microalgal lipid production for functional food and nutraceutical applications.  
Adsorption of Malachite Green Dye onto Bagasse Ash-Based Silica Aerogel/MgO Composite: Kinetic, Isotherm, and Thermodynamic Studies Nazriati Nazriati; Istighfarin Meilidya Azhar; Irma Kartika Kusumaningrum
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.1241-1256

Abstract

A silica aerogel/MgO composite synthesized from bagasse ash was investigated as a biomass-derived adsorbent for the removal of malachite green from aqueous solutions. The adsorption performance was systematically assessed through operational parameters, adsorption kinetics, equilibrium isotherms, and thermodynamic analyses. Comparative experiments demonstrated the superior adsorption capability of the silica aerogel/MgO composite relative to pristine silica aerogel, with adsorption capacities of 96.93 and 22.12 mg/g, respectively, recorded under the same experimental conditions, highlighting the beneficial interaction between the porous silica framework and MgO active sites. Equilibrium was attained after 80 min of contact time, and under optimum conditions, the composite achieved an adsorption capacity of 123.19 mg/g at 45°C with an initial dye concentration of 55 mg/L, while the highest removal efficiency (90.93%) was obtained at pH 9. Kinetic analysis revealed that the pseudo-second-order model most accurately represented the experimental data, yielding an R² value of 0.9923. Equilibrium studies further indicated that the Freundlich isotherm provided the best fit (R² = 0.9965–0.9973), suggesting adsorption on energetically heterogeneous surfaces with the possibility of multilayer uptake. Thermodynamic evaluation confirmed that the adsorption process occurred spontaneously and was favored at elevated temperatures, as evidenced by negative Gibbs free energy values (ΔG° = −4.68 to −6.29 kJ/mol), positive enthalpy changes (ΔH° = 12.46–15.29 kJ/mol), and positive entropy values (ΔS° = 58.76–67.10 J/mol·K). Overall, the results demonstrate the strong potential of the bagasse ash-derived silica aerogel/MgO composite as an efficient and sustainable adsorbent for the removal of cationic dyes from water.
Molecular Interaction and Crystalline Structure Reorganization of C. esculenta and M. leucadendra Extract-Loaded CS/PVA Electrospun Nanofibers Atina Atina; Idha Royani; Assa Idah; Miksusanti Miksusanti; Fitri Suryani Arsyad
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.795-807

Abstract

Understanding the molecular-to-structural evolution of extract-loaded electrospun systems is essential for rationally designing biofunctional nanomaterials. In this study, chitosan/polyvinyl alcohol (CS/PVA) electrospun nanofibers incorporated with Colocasia esculenta (CE) and Melaleuca leucadendra (ML) extracts were systematically investigated to elucidate the correlation between precursor solution interactions and resulting fiber morphology. Raman and UV-Visible spectroscopy were employed to probe molecular interactions and electronic transitions in electrospinning solutions. Extract incorporation induced vibrational band broadening and intensity suppression in Raman spectra, accompanied by increased absorbance and a red shift in UV–Visible spectra, particularly in the ML-containing system, indicating enhanced hydrogen bonding and greater electronic delocalization. Following electrospinning, structural characterization using XRD, FTIR, and SEM revealed progressive crystallinity reduction, peak shifting toward lower diffraction angles, hydrogen-bond-driven band broadening, and morphological evolution from smooth 90.86 ± 1.87 nm fibers (CS/PVA) to thicker 111.89 ± 2.96 nm fibers (CS/PVA/CE) and 118.48 ± 2.98 nm fibers (CS/PVA/ML). No separate crystalline extract phase was detected, confirming molecular-level dispersion within the polymer matrix. The ML-modified system exhibited the highest degree of amorphization and structural reorganization. These results establish a direct structure–property–function relationship, demonstrating that extract-induced modulation of intermolecular interactions governs crystalline organization, electrospinning dynamics, and nanofiber morphology. This study provides mechanistic insight into crystallinity engineering in plant-extract-loaded polymer systems and offers a scalable strategy for designing advanced bioactive electrospun nanomaterials.
Temperature Estimation of Geothermal Systems and Subsurface Model Based on Geochemical of Lake Ranau Mochammad Malik Ibrahim; Agung Harijoko; Wiwit Suryanto
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.773-783

Abstract

The geothermal potential of the Lake Ranau area comes from the remnants of magmatic activity from Mount Seminung. Geothermal manifestations in this area are in the form of hot springs that are thought to emerge through geological structures. This research aims to determine the approximate temperature of the geothermal system and subsurface model based on the analysis of chemical geothermometer method. The chemical geothermometer method can be used to indirectly predict the temperature of the subsurface geothermal system. Geothermal fluid manifestations in Kota Batu Village were chemically sampled by collecting three samples (LP 1, LP 2, and LP 3) and in Lombok Village by collecting three samples (LP 4, LP 5, and LP 6). Chemical geothermometers used in the research are silica, Na/K, K/Mg and Na-K-Ca geothermometers. The results of chemical geothermometer calculations on 6 samples of geothermal fluid manifestation locations, the estimated temperature of the subsurface geothermal system in the research area ranges from 177.0 - 285.6 0C and is included in the geothermal system with medium to high enthalpy. The subsurface model based on the calculation results of various chemical geothermometers about geothermal system components such as cap rock, reservoir rock, heat source, geological structure, thermal fluid and surface manifestations.
Engineering the Anatase-Rutile Phase Composition of TiO2 through H2O2 Addition and Its Photocatalytic Activity Sri Wahyuni; Sri Kadarwati; M. Alauhdin; Addy Rachmat; Nuril Huda; Eka Siti Rinjani; Ridho Prasetyo
Science and Technology Indonesia Vol. 11 No. 3 (2026): July
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.2026.11.3.955-971

Abstract

The synthesis of mixed-phase anatase–rutile TiO₂ has been carried out to improve its light response and photocatalytic activity. The synthesis of mixed-phase TiO₂ was performed through a sol–gel method in an alkaline solution and followed by a hydrothermal process in an autoclave at a temperature of 150 °C for 3 h. A 60 mL of 0.5 M HNO₃ was then added into the TiO₂ precipitate, followed by the addition of various amounts (0 mL, 10 mL, and 20 mL) of 30% H₂O₂. The suspension was homogenized by sonication for 30 min to obtain an anatase–rutile mixed phase. The resulting mixed-phase TiO₂ was further labeled as A0, A1, and A2, respectively. The High-Score analysis showed that the phase composition of TiO₂ was 9.4% anatase and 90.6% rutile (A0); 17% anatase and 83% rutile (A1); and 49.6% anatase and 50.4% rutile (A2). The diffuse reflectance spectra showed a shift in the band gap energy from 3.17 eV (fully anatase TiO₂) to 2.75–2.86 eV in A0, A1, and A2 mixed-phase TiO₂. These results suggested that the photocatalytic activity of A1 and A2 mixed-phase TiO₂ would occur in the early visible-light region (λ > 400 nm). The photocatalytic examination of the mixed-phase TiO₂ under LED and UV irradiation resulted in a decrease in rhodamine-B (Rh-B) concentration of up to 92%. However, the photocatalytic activity of mixed-phase TiO₂ did not outperform that of fully anatase TiO₂, which achieved a 98% reduction in Rh-B concentration.

Page 60 of 62 | Total Record : 616

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