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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 581 Documents
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Prime and Odd Prime Labelings on Cycle-Related Graphs Komarullah, Hafif; Hidayat, Noor; Krisnawati, Vira Hari; Wijaya, Kristiana
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.551-558

Abstract

Graph labeling is the process of determining integer values for vertices, edges, or both, based on certain criteria. Let G be a simple graph with the finite vertex set V(G). Prime labeling of G is a bijection ⍺:V(G)→{1,2,…,|V(G)|} for which each pair of adjacent vertices exhibits relatively prime labels. This concept has been extended to odd prime labeling, defined as a bijection ⍺:V(G)→ {1,3,...,2|V(G)|-1} satisfying the condition that the labels assigned to adjacent vertices are relatively prime labels. A graph that displays a (odd) prime labeling is designated as a (odd) prime graph. A recent conjecture state that every prime graph is an odd prime graph. In the present study, we conduct an investigation concerning prime and odd prime labeling, focusing on a range of cycle-related graphs classes. Our methods include the axiomatic descriptive approach and pattern detection techniques. We show that volcano graphs, C_3 ⨀_(x_1 y_0 ) F_n, C_3⊚K ̅_n, tadpole graphs, palm trees, and C_l ⨀_(x_1 y_0 ) mP_(n+1) are all both prime and odd prime graphs.
Some Properties of Generalized Token Graphs Muna, Naelufa Syifna Wifaqotul; Raventino; Utami, Rintang; Lia, Febby Desy; Huda, Muhammad Nurul; Susanti, Yeni
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.643-651

Abstract

The generalized k-token graph GFk(G) is a graph with the k-subsets of V(G) as the vertices, and two different vertices are adjacent if and only if the symmetric difference contains at least one edge of G. This model extends the classical k-token graph by relaxing the adjacency condition, leading to increased edge density and altered topological properties. In this paper, we establish the fundamental properties of GFk(G), including its connectivity, duality, and monotonicity. We provide exact formulas for the vertex degrees and the total size of GF2(G), along with combinatorial bounds for k > 2. Furthermore, we characterize the girth and clique numbers, proving that GFk(G) is highly prone to containing triangles even when the base graph is triangle-free. We also explore the inheritance of Hamiltonicity and bipartiteness, demonstrating that while connectivity is preserved, bipartiteness is lost for almost all bipartite graphs with at least four vertices. Our results provide a comprehensive structural characterization of this generalization, bridging the gap between classical token graphs and broader set-theoretic graph constructions.
Design and Formulation of Hydrogel Sponges for Mesenchymal Stem Cell Secretome Delivery Noviza, Deni; Ardelia, Syahda Permata; Marlina
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.692-700

Abstract

The mesenchymal stem cells (MSCs) secretome plays multiple roles in tissue regeneration and wound healing due to its content of various bioactive factors, including Fibroblast Growth Factor-2 (FGF-2). To support its topical application, an effective delivery system is required to preserve the stability and bioactivity of the secretome. A hydrogel sponge based on PVA-HPMC-PEG was selected as the delivery matrix due to its porous structure, flexibility, and ability to release active substances, thereby making it a promising candidate for wound healing applications. The objective of this research was to formulate a PVA-HPMC-PEG-based hydrogel sponge for a secretome delivery system. The hydrogel sponge was prepared using the freeze-drying method and optimized by varying the PVA concentration to achieve the desired physicochemical characteristics. The optimal formulation (F4) consists of 20% PVA, 2% HPMC, and 7.5% PEG. Evaluation revealed that this formulation exhibited a flexible sponge-like structure with a swelling percentage of 279.793% ± 0.06, elongation percentage of 107.923% ± 4.98, and physical crosslinking confirmed by FTIR analysis. Scanning Electron Microscopy (SEM) analysis demonstrated pore size ranging from 20 to 215 μm. Furthermore, secretome release was assessed using a Franz diffusion cell, and FGF-2 levels were quantified via ELISA. The results confirmed that the hydrogel sponge effectively facilitated the release of the secretome.
Block Bootstrap for Spatiotemporal Data in Generalized Space Time Autoregressive (GSTAR) Sumarminingsih, Eni; Fitriani, Rahma; Darmanto; Maulana, Eka Dani; Aulia, Natasha; Ruszardi, Luzar Dwain
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.701-731

Abstract

Generalized Space-Time Autoregressive is a model that can be used for data with spatial and temporal dependence. The GSTAR model is widely used in various phenomena such as rainfall, temperature, inflation, and others. GSTAR assumes normality of errors and non-autocorrelation. If the assumption of normality of errors is not met, then inference on parameters cannot be made. One solution to this problem is to use bootstrapping. However, bootstrapping for spatiotemporal data in the GSTAR model has not been developed. Therefore, this study aims to develop a bootstrapping method for spatiotemporal data in the GSTAR model. This development is done by adapting bootstrapping methods for time series data, namely, the non-overlapping block bootstrap (NBB) and the moving block bootstrap (MBB). This research continued with a series of simulations to evaluate the performance of the block bootstrap method as the number of observations, block length, and number of bootstrap replications were varied. Furthermore, the method’s effectiveness was tested using rainfall data from Malang Regency. Simulation results show that both resampling schemes satisfy the asymptotic condition, where the bias decreases monotonically with increasing sample size (T) and block length. MBB consistently produces lower bias than NBB due to its more intensive use of overlapping data, which effectively reduces boundary effects. Although inference on autoregressive parameters can be accurate, inference on spatial autoregressive parameters yields less satisfactory results, indicating the limitations of time blocks in capturing complex spatial dependencies. Increasing the number of replications above B=100 does not significantly improve the precision of the variance estimate, indicating computational efficiency at that threshold. The t-test results confirm that there is no statistically significant difference in performance between NBB and MBB. Nevertheless, MBB is more recommended for practical applications due to its higher information density and better estimation stability.
Geospatial Intelligence (GEOINT)-Based Cyber Warfare Exposure Index (CWEI) Mapping of Indonesia's Strategic Infrastructure Adityayuda, Anugrah; Supriyadi, Asep Adang; Arief, Syachrul
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.677-691

Abstract

The increasing integration of digital systems into critical infrastructure has transformed cyber warfare into a systemic national security risk with strong spatial characteristics. In Indonesia, rapid digitalization and uneven infrastructure development have expanded the cyber-attack surface, while existing studies remain largely qualitative or rely on aggregated national indices that fail to capture subnational exposure patterns. This study addresses this gap by developing a Cyber Warfare Exposure Index (CWEI) based on Geospatial Intelligence (GEOINT) to assess provincial-level exposure across Indonesia. The index integrates seven indicators, energy, transportation, telecommunications, government facilities, internet penetration, night-time light intensity, and urbanization, derived from open-source geospatial data and official statistics. All indicators were normalized using min–max scaling and aggregated through equal weighting, with robustness tested using Principal Component Analysis (PCA), Pearson correlation, and One-at-a-Time sensitivity analysis. Results reveal strong spatial disparities in cyber warfare exposure, with CWEI values ranging from 0.019 to 0.746. DKI Jakarta exhibits the highest exposure (CWEI = 0.746), followed by West Java (0.573) and Central Java (0.564), while several eastern provinces fall into the very low exposure category. The equal-weight and PCA-based indices show near-perfect agreement (R² = 0.997; r = 0.998), confirming high methodological robustness. Global Moran's I (0.689; p < 0.001) indicates significant positive spatial clustering of exposure. These findings demonstrate that cyber warfare exposure in Indonesia is highly concentrated and spatially structured, underscoring the need for regionally prioritized, risk-based cyber defense strategies.
Enhancing Chitosan-Carboxymethyl Chitosan Composite Film Properties by Silver Nanoparticles Grafting for Acne vulgaris Dwi Mulyana, Septian; Agus Syamsur Rijal, Muh.; Sari, Retno
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.559-568

Abstract

Silver nanoparticles (AgNPs) have been widely used in developing antibacterial preparations. AgNPs are used in film preparation to enhance the film’s antibacterial properties. The combination of natural polymers is an effective strategy to enhance mechanical properties, prolong degradation time, preserve gas and vapor permeability, and maintain biocompatibility. This research aims to develop an AgNP-chitosan-carboxymethyl chitosan (CMChi) nanocomposite film that exhibits desirable physical properties and enhances antibacterial activity by incorporating AgNPs. Chitosan-CMChi composite films were prepared using the solvent casting method. Characterization and antibacterial tests using Propionibacterium acnes (P. acnes) were carried out for AgNO3 and AgNP-chitosan-CMChi nanocomposite films. The results showed that a 1 mM AgNO3 solution with 1% lime powder at pH 9 was the optimal formulation for AgNP formation, exhibiting an absorbance of 4.631 at 408.1 nm, a particle size of 68.4 nm, and antibacterial activity. To optimize the chitosan-CMChi composite film, a formula of 1.5% chitosan and 1.5% CMChi was selected, yielding a tensile strength value of 0.514 MPa. The AgNP solution was then added. In the AgNP-chitosan-CMChi nanocomposite film, it was observed that increasing the AgNP volume affected the mechanical strength of the film. The antibacterial activity of the AgNP-chitosan-CMChi nanocomposite film increased with the AgNP concentration. Combining AgNPs with the chitosan-CMChi polymer yields nanocomposite films with good physical properties and enhanced antibacterial activity against P. acnes compared with films without AgNPs.
Potency of Leaf Water Extract Karamunting (Rhodomyrtus tomentosa) for Enhancing GLUT4 Translocation in Diabetic Rats Saleh, Irsan; Sutandar, Vivi Hendra; Amrina; Ningrum, Evi Dodik Novita; Sinaga, Ernawati
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.742-749

Abstract

Insulin resistance and damage in the pancreas are associated with type 2 diabetes, which is a chronic disease affecting health, with 422 million people affected in 2016 and 1.5 million deaths related to diabetes in 2012. Several proinflammatory mediators, such as TNF-a andIL-6, may be involved in insulin resistance in T2DM. GLUT4 is one of the glucose transporters that help promote glucose uptake. GLUT4 activation is insulin-dependent in regulating glucose uptake. Karamunting (Rhodomyrtus tomentosa (Ait.) Hassk.) leaf water extract consists of alkaloids, flavonoids, triterpenoids, saponins, and tannins. This study proposes to investigate the potential of karamunting (R. tomentosa) leaf water extract to enhance glucose uptake by modulating GLUT4 translocation in the serum and skeletal muscle of diabetic rats. The dose variations used in this study were 100 mg/kgBW, 200 mg/kgBW, and 400 mg/kgBW. Based on the results, oral administration of karamunting water extract increases GLUT4 expression in serum. It increases GLUT4 mRNAlevels in the skeletal muscle of the diabetic rat. It decreases TNF-a and IL-6 expression, with a 100 mg/kg BW dosage being the most effective. Meanwhile, 100 mg/KgBW is the most effective dosage for decreasing HOMA IR. These results indicate that karamunting (R. tomentosa) leaf water is antidiabetic by lowering TNF-a, IL-6, and HOMA IR in diabetic rats while increasing GLUT4.
Spatial Data Science for Regional Pattern Analysis: Dynamic Time Warping-Based Clustering of East Java’s Economic Indicators Fitriani, Rahma; Sumarminingsih, Eni; Diartho, Herman Cahyo
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.569-578

Abstract

Motivated by the need to better capture dynamic regional disparities, this study examines spatial and temporal development patterns in East Java, Indonesia, using spatial panel data from 2020 to 2023. A data-driven framework is proposed that integrates Principal Component Analysis (PCA) for dimensionality reduction, Dynamic TimeWarping (DTW) for temporal similarity measurement, and spatially constrained clustering using the SKATER algorithm. PCA compresses multiple socio-economic indicators, GDP growth, GDP level, Human Development Index (HDI), and population density, into a unified development profile, enabling comparison of regional trajectories over time. DTW captures non-linear temporal alignment, while SKATER preserves spatial coherence in cluster formation. The resulting clusters are used to construct an endogenous spatial weight matrix that reflects functional regional relationships rather than purely geographic adjacency. Validation using Moran’s I indicates stronger spatial autocorrelation compared to conventional contiguity-based weights, suggesting improved representation of spatial interaction. Four clusters reveal distinct development patterns and uneven regional trajectories. By integrating dimensionality reduction with temporal alignment and spatial clustering, the proposed approach extends dynamic spatial weighting toward a functional interpretation of regional dependence and offers a transferable framework for spatial data science and regional policy analysis.
Evaluation of Photocatalytic and Catalytic Activity of Biochar/Nickel for Laboratory Wastewater Treatment Fatimah, Is; Solekah; Nurlaela, Nunung; Ahmad, Zeeshan; Rizky, Indah Tri; Kamari, Azlan; Sagadevan, Suresh; Doong, Ruey-an
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.579-595

Abstract

In this investigation, an exploration on the use of low-cost effective methods for laboratory wastewater treatment using magnetic biochar has been conducted. Magnetic biochar derived from orange peel waste loaded with nickel nanoparticles (Biochar/Ni) was prepared by pyrolysis procedure of orange peel waste with nickel chloride as nickel precursor at 600 oC for 2 h. X-ray diffraction (XRD), scanning electron microscopy-energy dispersive x-ray (SEM-EDX), Raman spectroscopy, and vibrating sample magnetometer (VSM) were employed for identify the feature of Biochar/Ni. Photocatalytic, photocatalytic oxidation, and microwave-assisted catalytic peroxidation were the treatment procedures employed to evaluate the activity of Biochar/Ni. The results showed the dispersed nickel nanoparticles in the composite are photocatalytic system to produce radicals for decolorizing laboratory wastewater as proven by accelerated oxidation by the addition of H2O2 and S2O82- as oxidants, and inhibition by the addition of radicals and superoxide radical scavengers. In addition, microwave-irradiation intensified catalytic peroxidation with shorter time and higher decolorization efficiency. The greenness evaluation of the process using AGREE software addressed the microwave-assisted catalytic peroxidation as the most efficient procedure utilizing Biochar/Ni for being developed and implemented to organic contaminated wastewater.
Hierarchically Structured Zn-Al LDH/Hydrochar from Rambutan Peel (Nephelium lappaceum L.) for Enhanced Fe(II) Adsorption Erviana, Desti; Normah, Normah; Arieveali, Heroldinho; Ramadhan, Navinda
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
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.2026.11.2.524-537

Abstract

Dissolved ferrous ions in water pose significant environmental and operational challenges, necessitating efficient and sustainable removal technologies. In this study, a hybrid adsorbent was developed by integrating Zn-Al layered double hydroxide (LDH) with hydrochar derived fromrambutan peel (Nephelium lappaceum L.) via coprecipitation. Characterization confirmed successful composite formation with a substantial increase in specific surface area from 9.621 m2.g-1 for pristine Zn-Al LDH to 52.964 m2.g-1 for the composite, accompanied by enlarged pore volume and enriched oxygen-containing functional groups. Batch adsorption experiments showed strong pH dependence, with optimal Fe(II) removal at pH 6 and equilibrium reached within 120 min. The Zn-Al LDH@NL-HC composite exhibited a markedly higher adsorption capacity (51.501 mg.g-1) compared with Zn-Al LDH (15.692 mg.g-1) and hydrochar alone (8.594 mg.g-1), indicating a significant synergistic effect. Isotherm analysis revealed a maximum adsorption capacity of 76.336 mg.g-1 at elevated temperature, while kinetic data followed a pseudo-second-order model, suggesting chemisorption-dominated uptake. Thermodynamic parameters indicated an endothermic and spontaneous process. Regeneration studies demonstrated excellent stability, with adsorption efficiency maintained at 79.48% after five cycles. The superior performance is attributed to combined mechanisms including electrostatic attraction, surface complexation with oxygen-rich groups, ion exchange within LDH interlayers, and diffusion into mesoporous structures. These findings demonstrate the effective valorization of agricultural waste into a high-performance and reusable adsorbent for Fe(II) remediation in aqueous systems.

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