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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
 1 
Search results for , issue "Vol. 23, No. 4" : 8 Documents clear
Catalytic Cracking of Methyl Ester from Used Cooking Oil with Ni-Ion-Exchanged ZSM-5 Catalyst Alfernando, Oki; Sarip, Rozie; Anggraini, Titin; Nazarudin, Nazarudin
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

Fossil crude reserves continue to decline, eventually leading to a reduced availability of fuel oil in Indonesia. Thus, the use of alternative plant-derived renewable energy sources, such as biodiesel should be considered. However, biodiesel as a fuel alternative has many drawbacks. In this study, biodiesel was cracked using a Ni-ZSM-5 catalyst to improve its quality. This work aimed to synthesize and characterize the Ni-ZSM-5 catalyst obtained from ion-exchange and catalytically crack methyl esters from used cooking oil. Three Ni-metal concentrations (1%, 2%, and 3%) were used for the ion-exchange of ZSM-5. Ni catalysts were then utilized for catalytic cracking at three temperatures (450 ºC, 500 ºC, and 550 ºC). X-ray diffraction and scanning electron microscopy (SEM) analysis showed that the catalyst was in an aggregate form. SEM-energy-dispersive X-ray spectroscopy analysis indicated that Ni was successfully adsorbed by the catalyst. The gravimetry of the catalytically cracked product revealed that the highest oil fraction was obtained using 1% Ni catalyst at 450 ºC. The largest chain obtained with this catalyst was diesel oil (C13-C19) with total 92.96% of covered peak area in the chromatogram/component quantity from gas chromatography.
Grass-Like Structured Mesoporous Carbon as an Acid Red 119 Dye Adsorbent Krisnandi, Yuni Krisyuningsih; Priantini, Tania; Faisal, Muhammad; Yunarti, Rika Tri; Saragi, Indah Revita; Gunlazuardi, Jarnuzi
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

Grass-like structured mesoporous carbon was prepared by the soft-template method using triblock copolymer Pluronic F127, affording an organic–organic composite structure between phloroglucinol and formaldehyde. Thermogravimetric analysis revealed that the as-synthesized mesoporous carbon is stable to 900 °C, and X-Ray Diffraction (XRD) analysis confirmed the presence of carbon material structures at 2θ values of 22.020° and 42.420°. A hysteresis loop at relative partial pressures (P/Po) between 0.45 and 0.85 was observed in the N2 adsorption isotherm, indicating that the solid material exhibits mesoporous characteristics, with a homogeneous pore size distribution of 8.863 nm. Scanning Electron Microscope (SEM) images revealed that the bulk carbon surface exhibits a uniform grass-like structure. Furthermore, the as-synthesized mesoporous carbon was investigated for the adsorption of a diazo dye Acid Red 119, and it exhibited an adsorption capacity of 217.7389 mg/g; this capacity is 1.53 times greater than that of commercial activated carbon. Therefore, this mesoporous carbon is a potential adsorbent for the treatment of synthetic coloring waste.
Optical Properties of Toluene-soluble Carbon Dots Prepared from Laser-ablated Coconut Fiber Isnaeni, Isnaeni; Suliyanti, Maria Margaretha; Shiddiq, Muhandis; Sambudi, Nonny Soraya
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

In this study, we used laser ablation to fabricate toluene-soluble carbon nanoparticles from coconut fiber. In response to excitations at various wavelengths, the fabricated carbon nanoparticles exhibit three distinctive emission peaks at wavelengths of 300 nm, 440 nm, and 540 nm. These three emission peaks correspond to the  orbital state,  orbital state, and surface state, respectively. Photoluminescence excitation measurements indicate a high probability of energy transfer between the surface state and  orbital state, whereas the  orbital state is likely independent of the other states. The results of time-resolved photoluminescence measurements indicate that electrons are likely to remain longer in higher-energy states. Given that the carbon dots fabricated in this study were made from natural resources, these findings may find application in photonic devices that feature tunable emissions.
Thonningia sanguinea Vahl. (Balanophoraceae) in Southern Nigeria: II. Patterns of Genetic Diversity and Population Structure within and between Populations Imarhiagbe, Odoligie; Aigbokhan, Emmanuel Izaka
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

Studies have yet to assess the genetic variability in Thonningia sanguinea populations in Southern Nigeria. Hence, this study was conducted to elucidate the pattern of genetic variability and population structure among T. sanguinea populations in Southern Nigeria. Genomic DNA was extracted from 31 individuals in 15 populations and tested using random amplified polymorphic DNA (RAPD) primers. Several genetic diversity parameters were examined using GenALEx Ver. 6.5. Reproducible RAPD markers indicated that all the sampled populations were composed of individuals with a high genetic variability. The populations were grouped into four distinct clusters. The populations from the Okour community forest had high gene diversity and Shannon index. Conversely, the populations from Cross River National Park had the lowest gene diversity and Shannon index. Genetic variability did not correlate with geographic distances. Analysis of molecular variance revealed that most (82.3%) of the diversities could be explained by allelic variations within the population. An indirect estimate of gene flow yielded gave an Nm of 1.09, indicating a low migration level among populations. Results demonstrated that T. sanguinea populations in Southern Nigeria exhibited outcrossing strategy expected of the sexual exchange of gametes by different individuals within a local population.
Copper-nickel-modified Boron-doped Diamond Electrode for CO2 Electrochemical Reduction Application: A Preliminary Study Jiwanti, Prastika Krisma; Aritonang, Rani Puspitasari; Abdullah, Imam; Einaga, Yasuaki; Ivandini, Tribidasari Anggraningrum
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

CO2 electrochemical reduction (CO2ER) activity is known to be influenced by electrode materials. In this study, we report the fabrication of a copper-nickel-modified boron-doped diamond (CuNi-BDD) electrode using wet chemical seeding and electrodeposition. Annealing was performed to improve the stability of the modified electrode during elec-trolysis. Characterization of the modified BDD electrodes shows successful deposition without damage to the surface of the BDD support material. CO2ER was conducted with the CuNi-BDD electrode, which produces various important products including methanol, formic acid, CO, and CH4. Additionally, a different applied potential affected the product distribution. CO2ER was also conducted on the surfaces of Cu-BDD and Ni-BDD electrodes for comparison.
Degradation of Cypermethrin by Indigenous Bacteria from Contaminated Soil Indratin, Indratin; Kurnia, Asep; Wahyuni, Sri
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

Soil contamination by pesticides should be controlled by using soil microbes with the ability to degrade pesticide resi-dues. Microorganisms that have adapted to a particular pesticide could accelerate the degradation process. The present study aimed to select bacteria in soil that could potentially degrade cypermethrin residues. Experiments were carried out in a laboratory and employed soil samples collected from the districts of Demak, Magelang, and Brebes. Each soil sample was initially tested for the presence of bacteria and pesticide residues. Indigenous microbes capable of living in contaminated environments were adapted to cypermethryn and cultured in the laboratory. Experiment was carried out in several stages, namely, (1) isolation and identification of microbes that could degrade cypermethrin, (2) testing of the growth characteristics of isolates in cypermethrin, and (3) determination of cypermethrin residues in cultures. Three isolates, namely Pseudomonas alcaligenes, Bacillus amyloliquenfaciens, and Pseudomonas aeruginosa, were found to decrease cypermethrin residues by up to 95% with fast half-lives and good growth capability. The results demonstrate the potential applications of the isolates in biodegradation processes and remediation of cultivation fields.
Impact of El Niño and El Niño Modoki Events on Indonesian Rainfall Iskandar, Iskhaq; Lestrai, Deni Okta; Nur, Muhammad
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

On an interannual time-scale, the Indonesian climate is strongly influenced by the dynamics of Indo-Pacific climate modes. This study aims to investigate the possible impact of different types of El Niño events, namely, typical El Niño and El Niño Modoki, on Indonesian rainfall variability. Seasonal composite analysis was used to evaluate the magnitude and significance level of the influence of El Niño on the rainfall variability over the Indonesian region. Typical El Niño (hereafter El Niño) has a stronger influence on Indonesian rainfall than the El Niño Modoki during boreal autumn in September, October, and November when the events almost reach their peak. Cold sea surface temperature (SST) anomalies were observed in the Indonesian sea and in the western Pacific during El Niño years, while cold SST anomalies covered only the eastern Indonesian sea during El Niño Modoki years. Strong cold SST anomalies during El Niño years led to stronger low-level wind divergence over the Maritime Continent compared with that during El Niño Modoki years. In addition, the Walker circulation during El Niño years revealed a stronger downward motion over the Maritime Continent than that observed during El Niño Modoki years. This stronger downward motion (low-level wind divergence) during El Niño years reduced lower atmospheric water vapor and suppressed atmospheric convection over the Maritime Continent, leading to a significant decrease in rainfall. Similar situations were also observed during El Niño Modoki years but with a much weaker amplitude.
A Mathematical Model of Regulatory Mechanisms of Hepatocytes and Hepatitis B Saidalieva, Mahruy; Hidirova, Mohiniso Baxromovna; Turgunov, Abrorjon Makhamatsolievich
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

The study of the functioning of hepatitis B viruses in liver cells using methods of mathematical modeling is considered one of today’s pressing issues. In this article, the domains of functional- differential equations in a mathematical model of regulatory mechanisms of hepatocytes interacting with hepatitis B viruses (HBV) are presented. Characteristic molecular genetic systems regulatory mechanisms of the interrelated activities of liver cells and HBV are analyzed. A series of computational experiments show that the “chaos” and “black hole” theories describe two of the more dangerous regimes. As a result of the analysis of the “chaos” regime, small regions with normal behavior, “r-windows” were revealed. These regions allow the system to move from a “chaos” regime to a “regular” or normal regime. The features of the area of the regulatory activities of molecular genetic mechanisms of hepatocytes and HBV under a chaotic regime were characterized by analyzing the dynamics of the Lyapunov exponent. Small regions with regular behavior, “r-windows” in the field of dynamic chaos were defined. The regulatory nature of hepatocytes and HBV can be moved from the region of dynamic chaos to the normal region by using “r-windows”. The results of a computational experiment quantitatively analyzing the regulatory mechanisms of liver cells and HBV are presented.

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