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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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A Comparison Study between Green Synthesis of Microwave Irradiation and Solvent Evaporation Methods in The Formation of p-Methoxycinnamic Acid-Succinic Acid Cocrystals Sulistyowaty, Melanny Ika; Setyawan, Dwi; Prameswari, Putu Pradnya Mimba; Susilo, Raden Joko Kuncoroningrat; Amrillah, Tahta; Zaini, Erizal; Zidan, Sabry A. H.
Science and Technology Indonesia Vol. 9 No. 3 (2024): 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.2024.9.3.629-636

Abstract

Cocrystal of p-Methoxycinnamate acid-succinic acid has been produced by microwave irradiation and solvent evaporation methods. Cocrystals are formed using succinic acid as the coformer at a molar ratio of 1:1. The formation of cocrystal can be done by solvent evaporation method and microwave radiation method. Physicochemical properties have been studied by FT-IR, DSC, PXRD, and SEM analysis. The solubility test was carried out with pH 6.8 phosphate buffer at a temperature of 25±0.5°C for 5 hours and the dissolution test was carried out with 900 mL pH 6.8 phosphate buffer at a temperature of 37±0.5°C with the speed of 75 rpm using a paddle-type dissolution test apparatus. The solubility of PMCA has increased its solubility in cocrystals by the solvent evaporation method by 1.19 times and by the microwave radiation method by 1.16 times compared to PMCA. The dissolution rate of the cocrystals of the solvent evaporation method increased by 3.50 times and the cocrystals of the microwave radiation method increased by 2.29 times compared to PMCA.
Isolation and Characterization of Cellulose Nanofibrils (CNF) from Dates by-Product via Citric Acid Hydrolysis Aisy, Laaili Azti Rohaadatul; Kemala, Tetty; Suryanegara, Lisman; Purwaningsih, Henny
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.2024.9.4.818-827

Abstract

Industrial residues that are not optimally utilized are removed by burning, landfilling, or dumping, which can threaten the environment and health. In fact, part of this agro-industrial waste still has content that has the potential to become raw material for value-added other industries. Dates by-product as residue of the fiber-rich fruit industry have the potential to be a source of nanocellulose. This study aims to obtain nanofibril cellulose (CNF) isolates from dates by-product via citric acid hydrolysis, and investigate the effect of acid concentration on the unknown dates by-product CNF isolate characteristics. Pretreatment such as delignification and bleaching is needed to obtain cellulose isolate with high purity. Furthermore, acid hydrolysis, centrifugation, and sonication are performed to obtain CNF. CNF isolates are characterized by the analysis of particle size distribution, morphology, and crystallinity. Analysis of functional groups and lignocellulose content test confirm that lignin and hemicellulose are degraded during isolation. The particle size distribution measurement shows that the greater the acid concentration, the smaller the CNF size and the better the size uniformity. The morphology of the CNF obtained is net-like fibers. The degree of crystallinity shown decreases with increasing acid concentration. This study revealed that different citric acid concentrations can result in different characteristics of CNF isolates.
Methyl Ester Sulfonate (MES) Surfactant Production from Waste Cooking Oil (WCO) with Microwave Technology Qadariyah, Lailatul; Ryvalda, Dhea Septyanonie; Aditama, Narendra Yudha; Aswie, Viqhi; Mahfud, Mahfud
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.2024.9.4.929-940

Abstract

Traction Energy Asia 2020 reported that 3 million kilolitres of WCO were collected in Indonesia in 2019, 1.6 million kilolitres from urban households. WCO poses risks due to common reuse or disposal. Repurposing for MES surfactant is vital. Hence, this study aims to produce an MES surfactant from WCO feedstock using NaHSO3 as a microwave-assisted reactant by observing the influence of variables such as reactant mole ratio, catalyst concentration, sulfonation reaction time, and microwave power. The adsorption method involves vacuum filtration of WCO to remove impurities, mixing with activated carbon, and settling before a second filtration. Transesterification transforms WCO into methyl ester through mixing with methoxide solution with a molar ratio of methanol to WCO of 1:9 and a 1 wet% NaOH catalyst based on WCO, followed by washing and drying. Sulfonation involves reacting methyl ester with NaHSO3 (1:1, 1:2, 1:3, 1:4) and CaO catalyst (1%, 1.5%, 2%, 2.5%). The reaction occurs in a microwave at power variations of 300, 450, 600, and 750 Watts, as well as with variations in time of 20, 30, 40, 50, and 60 minutes. After that, it ends with purifying and neutralizing to produce MES. The optimal conditions for MES production are a 1:2 molar ratio of reactants, 1.5% CaO catalyst concentration, 20 minutes, and 450 W, yielding 48.06%. MES characteristics: pale yellow color, density of 0.859 g/cm3, viscosity of 1.780 cSt, and surface tension of 32.62 dyne/cm. FTIR analysis confirms sulfonic acid groups at 1195.27 cm−1 and 1169.1 cm−1 wavelengths.
Plectranthus scutellarioides (L.) R.Br. Leaf Extract as Sunscreen, Skin Lightening, and Antiaging Widyastuti, Widyastuti; Elmitra, Elmitra; Wardi, Epi Supri; Agustin, Diana
Science and Technology Indonesia Vol. 9 No. 3 (2024): 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.2024.9.3.745-755

Abstract

Plectranthus scutellaroides is a plant with attractive colored leaves. It contains secondary metabolite compounds such as flavonoids and phenolics, which provide skin protection against ultraviolet rays from the sun. The research aims to investigate the activity of P. scutellarioides leaf extract from various variants and different solvents on sunscreen, skin lightening, and anti aging activities. The best extract is formulated in gel dosage form. Each P. scutellaroides leaf was extracted using ethanol, ethyl acetate, and hexane as solvents. The obtained extract was assessed for Sun Protecting Factor (SPF), UVA Protection grade (PA), antioxidant activity, and inhibition of tyrosinase, collagenase, elastase, and hyaluronidase. Determination was conducted in vitro using spectrophotometric methods. The highest sunscreen activity was observed in the ethanol extract Va (Va-ET), which exhibited SPF and PA values of 25.618±0.265, and 0.681±0.007 (star 3), respectively at a concentration of 100 ug/mL. The most significant skin-lightening activity was observed in the ethanol extract Vc (Vc-ET), with an IC50 value inhibiting tyrosinase of 39.059 ug/mL. Regarding the anti-aging activity of the extracts, as determined by their antioxidant activity and inhibition of collagenase, elastase, and hyaluronidase, the most promising extracts were obtained from ethanol extract Va (Va-ET) and ethyl acetate extract Va (Va-EA), with IC50 values of 79.734, 76.838, 143.384, and 122.467 ug/ mL, respectively. The Va-ET was formulated into a gel dosage form, and there was a significant effect of the gelling agent on the SPF value of the extract after formulation (p < 0.05). All extracts exhibit activity as sunscreen, skin lightening, and anti-aging, with the Va-ET showing the highest efficacy. Gelling agents significantly influence the SPF value of extracts after formulation into the gel dosage form. Among them, F3, formulated from the Va-ET of P. scutellaroides using Carbopol-940 as a gelling agent, exhibits the highest efficacy.
High Sensitivity CH4 and CO2 Gas Sensor Using Fiber Bragg Grating Coated with Single Layer Graphene Irawan, Dedi; Saktioto; Dwi Hanto; Widiyatmoko, Bambang; Sutoyo
Science and Technology Indonesia Vol. 9 No. 3 (2024): 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.2024.9.3.710-717

Abstract

This article outlines the development of a Fiber Bragg Grating (FBG) intended for use as a sensor for CH4 and CO2 gases. Following fabrication, the FBG was effectively treated with a layer of Graphene Material through a modified RF Sputtering process. This coating procedure involved introducing argon gas into the chamber and subjecting the FBG, securely held by two vacuum stages, to a temperature range of 27°C to 600°C by adjusting the power supplied to the cathode and anode, ranging from 0 to 125 Watts. Subsequently, the FBG was employed as a key sensing element within an experimental setup aimed at measuring gas concentrations within a confined space. The assessment involved analyzing the reflected signal of the FBG using an Optical Interrogator System, which demonstrated a shift in the Bragg wavelength of the reflected signal corresponding to varying gas concentrations. This study indicates promising outcomes for the Graphene-coated FBG as a gas sensor. The sensor’s sensitivity was evaluated based on the Bragg wavelength shift resulting from gas presence within the chamber. The Graphene-coated FBG exhibited sensitivities of 3.3 ppm for CH4 and 3.7 ppm for CO2, surpassing those reported in prior research efforts.
Europium-Subsituted Bismuth-Based Superconductors: Structural and Thermal Analysis via Chemical Sol-Gel Synthesis Salim Abed, Firas; Abbas, Lamia K.
Science and Technology Indonesia Vol. 9 No. 3 (2024): 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.2024.9.3.621-628

Abstract

The synthesis and characterization of Bi1.7-xPb0.3EuxSr2Ca2Cu3O10+δ superconductors with Eu substitution at varying ratios were investigated to determine their structural, electrical, and thermal properties. A sol-gel technique followed by calcination was employed to prepare samples with different substitution ratios. X-ray diffraction (XRD) was used for structural analysis, electrical properties with aid of nitrogen fluid measured by electrical resistivity, thermogravimetric analysis (TGA) conducted for thermal properties , and differential scanning calorimetry (DSC) were utilized for characterization" to improve clarity. XRD analysis revealed that the highest proportion of the high-temperature superconducting (HTS) phase occurred at a substitution factor of 0.2, corresponding to the highest critical temperature (Tc) value of 112 K. Raman spectra were conducting and showed a certain shifting with different substitution levels of Eu element. The thermal analysis highlighted the impact of substitution factor x on thermal stability, with the sample at x=0.2 exhibiting the highest thermal stability. TGA curves showed mass loss behavior for different x values, with distinct regions indicating the presence of residuals. The successful synthesis and characterization of these superconductors hold promise for practical applications.
Assessment of Commercial DNA Extraction Kits for Porcine Gelatin Detection Using RT-PCR and ddPCR Gina, Safira; Rahmagiarti, Cintera; Ummah, Isna Mustafiatul; Sumantri, Cece; Suparto, Irma Herawati; Darmawan, Noviyan
Science and Technology Indonesia Vol. 9 No. 3 (2024): 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.2024.9.3.605-612

Abstract

Gelatin is extensively applied in various industries, including food, beverages, cosmetics, and pharmaceuticals. Although the determination of gelatin species is essential for religious, health, and consumer preference reasons, a standardized analysis method is absent. The challenge in identifying gelatin through DNA-based methods arises from the low DNA content and extensive DNA denaturation in the gelatin matrix. This study assessed the efficacy of two commercial DNA extraction kits, namely the Processed Food DNA Extraction (PF kit) and the DNeasy Mericon Food Kit (DM kit), for extracting DNA from porcine gelatin powder and commercial products derived from gelatin. Additionally, we evaluate the amplification of the extracted porcine DNA using real time polymerase chain reaction (RT-PCR) and droplet digital polymerase chain reaction (ddPCR) techniques. The PF extraction kit demonstrated successful DNA extraction from porcine gelatin powder and commercial samples of porcine gelatin-based candies with a higher concentration (32.24-286.07 ng/uL) and purity (A260/A280 ratio of 1.82-2.33) compared to the DM kit (3.95-7.30 ng/uL and an A260/A280 ratio of 1.29-2.45). RT-PCR and ddPCR analyses yielded positive results for porcine DNA from gelatin powder for both PF and DM kits, albeit with differing Cq values and copy numbers. The choice of DNA extraction kit significantly impacted the amplification results when analyzing commercial samples of porcine gelatin-based candies. Using RT-PCR, all samples yielded negative results with the DM kit, while the PF kit detected one positive result for porcine DNA. Improved outcomes were observed with more sensitive analysis methods such as ddPCR, where the DM kit identified one positive result for porcine DNA while the PF kit detected positive results for all tested candies.
Corn-Cob-Waste-Based Fe2.75Mn0.25O4/rGO Nanocomposite Application as Anti-Radar Coatings Saefullah, Lalu; Kormil Saputra; Wida Puteri Agista; Masruroh; Dionysius J. D. H. Santjojo; Istiroyah
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.2024.9.4.798-805

Abstract

Radar-absorbent materials (RAMs) have become essential technologies in fields that require them, such as the military. Their working principle is that they absorb electromagnetic waves and prevent their reflection. In developing the manufacturing of RAMs, high-performance materials are needed for effective use as RAMs. In general, RAMs possess two essential properties: magnetic and dielectric. This research reports the author’s successful synthesis of an Fe2.75Mn0.25O4/rGO nanocomposite as an anti-radar material using the coprecipitation method. Interestingly, the main precursors used were natural materials, namely iron sand and corn cob waste. XRD, FTIR, and SEM-EDX characterized the research samples to determine the nanocomposite’s structure and phase, functional groups, and morphology after doping. XRD characterization results showed that Fe2.75Mn0.25O4/rGO nanoparticles had a cubic crystal structure and that there were no new peaks, which indicates that Mn had been successfully substituted into Fe. FTIR test results showed that the Fe2.75Mn0.25O4/rGO nanocomposite had Mn and Fe-O functional groups in octahedral and tetrahedral positions at wave numbers of 418 480 cm-1 and that there were C=C functional groups at the wave number of 1629 cm-1. SEM results showed that the nanocomposite comprised Fe2.75Mn0.25O4/rGO particles in agglomerated spheres and corn-cob-based rGO in sheet form, with a grain size of around 26–31 nm. EDX test results showed the appearance of Fe, Mn, O, and C elements. It was also found that the 3-mm-thick Fe2.75Mn0.25O4/rGO nanocomposite sample achieved the highest reflection loss (RL) value of -43.6 dB at a frequency of 8.5 GHz, indicating a significant radar wave absorption capability.
Some Coefficient Problems for Subclasses of Holomorphic Functions in Complex Order Associating Sălăgeăn q-Differential Operator Yie, Tseu Suet; Janteng, Aini; Abbas, Muhammad
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.2024.9.4.981-988

Abstract

A function with complex values and at every point of the specific domain contains a derivative is commonly known as analytic functions which is also referred as holomorphic functions. We begin by interpreting \(A\) as the class for all holomorphic functions \(L(\xi)\) with a Taylor series expansion written in the form: \[L(\xi) = \xi + \sum_{i=2}^{\infty} x_i \xi^i\] where \(x_i \in \mathbb{C}\) and \(\xi \in D\). \(D\) is the open unit disk where \(D = \{\xi : \xi \in \mathbb{C}, |\xi| < 1 \}\). Furthermore, we suggest the subclass of \(A\) that is univalent in \(D\) represented as \(S\). It is commonly known that the main subclasses of class \(S\) are the class of starlike functions and the class of convex functions. To develop and analyze the Fekete-Szegö problems, the theory of geometric function contributes significantly to this. Moreover, the frequent use of \(q\)-calculus as a general direction of research among mathematicians has caught our attention. In this research, we attained the initial coefficients, \(x_2\) and \(x_3\), and the upper bound for the functional \(|x_3 - \nu x_2^2|\) of functions \(L\) in the two new subclasses that are introduced by involving the Sălăgeăn \(q\)-differential operator, \(M_q^\eta L(\xi)\) and the definition of subordination.
Nichrome Dependency in Welding Layer Using In situ Fabrication on Hardness and Corrosion Properties Syaripuddin; Sopiyan; Muhammad Fauzan Perdana Putra; Maman Kartaman Ajiriyanto; Sigit Dwi Yudanto; Muhammad Yunan Hasbi; Susetyo, Ferry Budhi
Science and Technology Indonesia Vol. 9 No. 3 (2024): 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.2024.9.3.651-659

Abstract

The use of shielded metal arc welding (SMAW) equipment to synthesize alloys is one of the most promising methods as it can be used for in-situ fabrication. The hardness and corrosion properties of the deposited layer during the welding process can be enhanced by dilution of nichrome (NiCr) during the process. Therefore, the alloy was synthesized on the surface of the mild steel using SMAW equipment with various NiCr additions. The properties of the alloy were investigated using an X-ray diffraction (XRD), an Optical microscope, a Potentiostat, and a Vickers hardness apparatus. The appearance of martensite overlaps with the ferrite phase could be affected by the addition of NiCr to the alloy. An increase in NiCr content is followed by an increase in the lattice parameter value of the ferrite phase. The presence of a certain amount of nickel (Ni) contributes to the formation of lower transformation phases, including martensite. At the same time, the incorporation of chromium (Cr) also plays a significant role in promoting the formation of acicular ferrite. An increase in NiCr content in NiCr2 and NiCr3 samples results in a quantitative increase in martensite formation. Adding 0.434 g of NiCr to the weld deposited layer could result in the corrosion rate of the alloy being 0.1118 mm/y. Higher hardness is found in the NiCr3 sample, around 742.06 HV.

Page 38 of 56 | Total Record : 551

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