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Ivandini Tribidasari A.
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Makara Journal of Science
Published by Universitas Indonesia
ISSN : 23391995     EISSN : 23560851     DOI : https://doi.org/10.7454/mss
Core Subject :
Makara Journal of Science publishes original research or theoretical papers, notes, and minireviews on new knowledge and research or research applications on current issues in basic sciences, namely: Material Sciences (including: physics, biology, and chemistry); Biochemistry, Genetics, and Molecular Biology (including: microbiology, physiology, ecology, taxonomy and evolution); and Biotechnology.
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Articles 8 Documents
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Search results for , issue "Vol. 24, No. 2" : 8 Documents clear
Natural Aluminosilicate-based Y Zeolite for Catalytic Cracking of n-Hexadecane Khatrin, Irena; Saragi, Indah Revita; Ekananda, Rizki; Hanna, John Vincent; Griffith, Benyamin E; Krisnandi, Yuni Krisyuningsih
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

Natural zeolite and kaolin are abundant in Indonesia especially in Java and Belitung islands. These materials generally contain high aluminosilicate minerals that can be used as silica and alumina sources for the formation of NaY zeolite. This research aimed to identify the modification of NaY zeolite structure using Bayat natural zeolite as alumina source and Belitung kaolin as silica source and its catalytic activity for n-hexadecane cracking. Pretreatment of materials were performed in several steps: activation, purification, fragmentation for Bayat–Klaten natural zeolite, and silica extraction for Belitung kaolin. The synthesis of NaY was performed hydrothermally using seed-assisted method with crystallization times of 24 and 48 h. The surface area analysis showed a typical surface area of microporous zeolite (i.e., a pore diameter of 1.897 nm) and surface area of 309.4 cm2/g. Meanwhile, powder X-ray diffraction characterization showed that the as-synthesized materials have the structure of NaY zeolite. The optimum crystallization time was 24 h with Si/Al ratio of 4.10. Furthermore, both synthetic and natural sourced NaY zeolites were converted into HY zeolites and employed as cracking catalyst of n-hexadecane in a fixed-bed reactor at 500 °C for 75 s. The natural sourced HY resulted in 59.80% conversion and 59.80% yield of gasoline product (C9–C12). These values were lower than the results given by synthetic HY (80%).
Improving the Surface Corrosion Resistance of AMX601 Magnesium Alloy by Acid–Alkaline Treatment Anawati, Anawati; Asoh, Hidetaka; Ono, Sachiko
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

A drawback of acid cleaning as surface finishing of magnesium (Mg) surface is the absence of a protective oxide film on its surface. Acid–alkaline treatment is proposed to enhance the surface corrosion resistance of AMX601 Mg alloy. Acid–alkaline treatment was conducted by first dipping the alloy in HNO3–H3PO4 solution and then immersing the al-loy in NaOH solution. The potentiodynamic polarization test in 0.9% NaCl solution at 37 °C revealed a nobler corro-sion potential of −1.36 VAg/AgCl and a lower corrosion current density of 36.0 µA•cm−2 of the acid–alkaline-treated spec-imen than the acid-treated (−1.44 VAg/AgCl, 89.7 µA•cm−2) and untreated (−1.52 VAg/AgCl, 40.0 µA•cm−2) specimens. Acid treatment induced a significantly higher surface roughness (20 µm) than acid–alkaline (10 µm) and grinding (0.5 µm) treatments because of the selective dissolution of the Mg matrix and the accumulation of intermetallic precipitates. The film formed on the acid–alkaline-treated specimen was thick and free of cracks, whereas that formed on the acid-treated specimen was thin and cleaved. The formation of a protective oxide film and the enrichment of cathodic intermetallic particles on the acid–alkaline-treated specimen enhanced the corrosion resistance of the surface.
Effect of Mechanical Milling on the Total Phenolic Content and Antioxidant Activity of Garcinia mangostana Pericarp Nugroho, Dwi Wahyu; Daratika, Dyah Ayu; Kamila, Muthia; Togatorop, Lusiana; Rifada, Mohammad Aulia; Widayatno, Wahyu Bambang; Maulana, Syahrizal; Setyawati, Damai Ria; Mardliyati, Etik; Rochman, Nurul Taufiqu
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

This study aimed to identify the effect of mechanical milling on the total phenolic content and antioxidant activity of mangosteen pericarp. Mangosteen pericarp was milled under different milling times (30, 90, 150, and 210 min). The particle morphology before and after milling was observed by scanning electron microscopy (SEM), and the average particle size was obtained from SEM images and analyzed statistically. The antioxidant activity was measured through the 2,2-diphenyl-1-picrylhydrazyl method. The total phenolic content for the non-milling sample was 14.52 × 104 µg GAE/g sample, and the highest total phenol content was 17.44 × 104 µg GAE/g sample for the sample milled for 210 min. The IC50 value decreased for samples with milling 150 and 210 min, which showed strong antioxidant activity, whereas the value of gallic acid equivalent increased. SEM observations showed the presence of agglomeration in the morphology of mangosteen pericarp samples. The average particle size of the mangosteen pericarp decreased as the milling time increased (up to 4499 nm for samples milled for 210 min). Therefore, mechanical milling had a significant effect on the phenolic content and antioxidant activity, which indicated an increase in the bioavailability of mangosteen pericarp.
Indigenous Microbial Biostimulation for Microbial Enhanced Oil Recovery through Oil Degradation with Variation in Nutrent Concentrations Handaruni, Rika; Astuti, Dea Indriani; Purwasena, Isty Adhitya; Afifah, Lulu Nur
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

Oil production in Indonesia has been declining since 2002, and this decline is incompatible with the high oil consumption in Indonesia. As such oil production in Indonesia should be improved. Biostimulation in microbial enhanced oil recovery involves environmental modification to stimulate microbial growth within a reservoir by adding limiting nutrients. Variation in C, N, and P concentrations injected to reservoirs can induce different responses from indigenous microbes and increase oil recovery. In this study, molasses, urea and diammonium phosphate were used as nutrients injected to a reservoir for biostimulation. Biological, physical and chemical characteristics after biostimulation were observed and bacterial growth was monitored up to 42 days. The physical characteristics observed were pH, oil viscosity, and interfacial tension. Gas chromatography mass spectrometry was performed to determine the chemical characteristics of oil. Results showed that the addition of nutrients at various concentrations yielded different production patterns of metabolites. The addition of urea and diammonium phosphate induced biosurfactants overproduction and increase hydrocarbon degradation of by bacteria. Therefore, hydrocarbons were degraded for the first 14 days, and polymerized again on days 14 to 42.
Antibacterial and Anti-Biofilm Activities of Culture Filtrates from Schizophyllum commune, Coniothyrium sp., and Fusarium sp. Hastuty, Aerma; Mairani, Rahma; Rosada, Keukeu Kaniawati
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Bacterial infections are usually caused by biofilms that are resistant to extreme conditions. Studies have shown that fungal extracts have the potential to inhibit biofilm formation. The aim of this study was to examine the activity of several fungal culture filtrates in inhibiting bacterial growth and biofilm formation. The fungi were identified by molecular method, and the effects of different concentrations (45%, 75%, and 90%), medium pH (6, 7, and 9), temperatures (30 and 37 °C), and incubation times (24, 48, and 72 h) of the filtrates on their anti-biofilm formation properties were investigated. Anti-biofilm assay was performed using the diffusion test and microtiter assay. The parameters examined included the diameter of the inhibition zone of each well and the optical density of the filtrate solution. Molecular identification based on ITS rDNA regions showed that the fungal isolates in this study were Schizophyllum commune (strain JSB2), Coniothyrium sp. (strain JB1-3), and Fusarium sp. (strain JBB2). Antibacterial assay showed that, among the culture filtrates obtained from all fungi, that from Fusarium sp. strain JBB2 exhibits the highest inhibitory activity. Biofilm inhibition assay further revealed optimum fungal culture filtrate activities at pH 7.
Investigation of Microstructure and Magnetic Properties of Zn1-xMnxO and Zn0.98-xMnxFe0.02O (x = 0, 0.05, and 0.09) prepared by Solid-state Reaction Method Sebayang, Perdamean; Kurniawan, Candra; Lubis, Ridwan Y; Priyadi, Ignu; N, Nasruddin M; Aryanto, Didik
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

In this study, we investigated the microstructure and magnetic properties of Zn1-xMnxO and Zn0.98-xMnxFe0.02O (x = 0, 0.05, and 0.09) powders prepared by the solid-state reaction method. The starting material, which consisted of ZnO, Mn, and Fe powders, were wet milled for 3 hours using high-energy milling. We then used an X-ray diffractometer (XRD), scanning electron microscope, and vibrating sample magnetometer to investigate the effects of doping and co-doping on the microstructure, morphology, and magnetic properties, respectively. The XRD results suggest that Mn and Fe ions had substituted into the ZnO matrix, as illustrated by the resulting single-phase polycrystalline hexagonal wurtzite structures. The diffraction intensity was observed to decrease as the Mn composition increased. The analysis showed that the lattice parameters decreased due to Mn2+ and Fe3+ ion substitution in the ZnO matrix. The co-doping of Mn-Fe ions in the ZnO structure enhanced the magnetic properties, particularly due to the Zn0.89Mn0.09Fe0.02O composition. The increase in the Mn dopant and Mn-Fe co-dopant concentrations strongly contributed to the improved morphology and magnetic properties. Therefore, we can conclude that the presence of Mn and Fe co-dopants in the ZnO system contributed to its magnetic properties, as confirmed by high-saturation magnetization.
Protein Annotation of Breast-cancer-related Proteins with Machine-learning Tools Parikesit, Arli Aditya; Agustriawan, David; Nurdiansyah, Rizky
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

One of the primary contributors to the mortality of women is breast cancer. Several approaches are used to cure it, but recurrence occurs in 79% of the cases because the underlying mechanism of the protein molecules is not carefully ex-amined. The goal of this research was to use machine-learning tools is to elucidate conserved regions and to obtain functional annotations of breast-cancer-related proteins. The sequences of five breast-cancer-related proteins (BRCA2, BCAR1, BCAR3, BCAR4, and BRMS1) and their annotations were retrieved from the UniProt and TCGA databases, respectively. Conserved regions were extracted using CLUSTALX. We constructed a phylogenetic tree using the MEGA 7.0. SUPERFAMILY database to obtain fine-grained domain annotation. The tree revealed that the BRCA2 and BCAR4 protein sequences are located in a clade, which indicates that they have overlapping functions. Several protein domains were identified, including the SH2 and Ras GEF domains in BCAR3, the SH3 domain in BCAR1, and the BRCA2 helical domain, the nucleic-acid-binding protein, and tower domain. We found that no protein domains could be annotated for BCAR4 or BRMS1, which may indicate the presence of a disordered protein state. We suggest that each protein has distinct functionalities that are complementary in regulating the progression of breast cancer, although further study is necessary for confirmation. This protein-domain annotation project could be leveraged by the complete integration of mapping with respect to gene and disease ontology. This type of leverage is vital for obtaining biochemical insights regarding breast cancer.
Biosensor and Chemosensor Fluorophores that contain Chalcogenide Centers Yudhistira, Tesla; Lee, Woo Hyun; Churchill, David G
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

In this timely review, we discuss the important attributes of various chalcogen-containing small-molecule probes that have been synthesized in the Molecular Logic Gate Laboratory at the Korea Advanced Institute of Science and Technology. Specifically, we discuss some of the important chemical and photophysical properties of these probes, including reversibility, responsiveness (response time), cellular localization, sensitivity to analytes, selectivity (toward a specific analyte in question), and some bioavailability criteria. Chalcogenides undergo reversible redox-type reactions with reactive oxygen species (ROS). These controlled solution reactions enable a sensible and clear response as they act to immediately affect the chemical and electronic properties of the chalcogen moiety. Often, the lone pair belongs to chalcogens, which communicate electronically with the rest of the probes. Importantly, chemically oxidized chalcogenides can revert to their original reduced (divalent) form through the addition of natural or unnatural biothiols (or other reductants). This phenomenon is considered reversibility from the standpoint of probes. It can also be called “resetability.” In this manner, a variety of fluorophore frameworks can be used to detect ROS and thiols. Further studies can help experimentally determine the lipophilicity and even the cellular localization of probes, which are important in assessing their value as diagnostic agents in biological sciences and their possible therapeutic potential.

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